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Catalysts
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Emerging Trends in TiO2 Photocatalysis and Applications
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Emerging Trends in TiO2 Photocatalysis and Applications

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Photocatalysis".

Deadline for manuscript submissions: closed (31 March 2019) | Viewed by 173234

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Trong-On Do

E-Mail Website
Guest Editor
Department of Chemical Engineering, Laval University, Quebec, QC G1V 0A6, Canada
Interests: hydrogen production; hydrogen evolution; catalysis/photocatalysis; nanomaterials; clean energy; solar fuels; environment
Dr. Sakar Mohan

E-Mail
Guest Editor
Centre for Nano and Material Sciences, Jain University, Bangalore 562112, India
Interests: photocatalysis; biomass conversion; perovskites; multiferroics; plasmonics; nanomaterials for energy and environmental applications

Special Issue Information

Dear Colleagues,

       The photo-assisted catalytic reaction, which is conventionally known as “photocatalysis”, is blooming in the field of energy and environment due to its multifaceted applications, such as in pollutant degradation, water splitting, fuel conversion, anti-microbial activities, etc. The photocatalytic process involves the separation of excitons upon light irradiation, and their subsequent transfer to the respective band energies (electrons to the conduction band and holes to valence band) to perform reduction and oxidation processes in order to execute the required transformation reactions. The key requirement to achieve the required application is to engineer a photocatalytic material with suitable band edge positions to produce the appropriate redox species.

       In this direction, titanium dioxide (TiO2) is one of the well-established and renowned photocatalysts that has been explored for various possible photocatalytic applications. However, along with suitable band edge positions, an efficient photocatalyst should also have (i) a narrow band gap energy so as to absorb visible light energy, (ii) enhanced charge separation, so as to have high quantum efficiency, (iii) enhanced recombination resistance to have prolonged reactions, and (iv) effective interfacial interactions to have intimate contact between the surrounding media and the photocatalyst, towards total conversion of the reactant.

       To handle these requirements in a photocatalyst, several modifications strategies have been developed, which broadly include doping, composite, plasmon sensitization, co-catalyst loading, integration of carbon-based materials, anisotropic nanostructuring of the photocatalyst, etc. As TiO2 is a pioneering material for any developments in the field of photocatalysis, this Special Issue is going to be focused on “Emerging Trends in TiO2 Photocatalysis and Applications”, featuring the state-of-the-art in the field. Research findings focusing the fundamental exploration of the syntheses, characterizations and applications in technological- and industrial-scale development of TiO2 in the field of photocatalysis are of prime importance to this Special Issue.

       Above all, we are glad to highlight that Prof. Akira Fujishima will be contributing a review paper in this Special Issue highlighting the recent trends in the field and featuring the modern photocatalysis.

Prof. Dr. Trong-On Do
Dr. Sakar Mohan
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Honda-Fujishima effect
  • Band gap engineering
  • Doped TiO2
  • TiO2 based composites
  • Nanostructured TiO2 photocatalyst
  • Plasmonic TiO2 photocatalyst
  • Defective TiO2 photocatalyst
  • Visible light driven TiO2
  • Pollutant degradations
  • Water splitting
  • Fuel conversions

Published Papers (31 papers)

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Editorial

Jump to: Research, Review

4 pages, 519 KiB  
Editorial
Editorial: Special Issue on “Emerging Trends in TiO2 Photocatalysis and Applications”
by Trong-On Do and Sakar Mohan
Catalysts 2020, 10(6), 670; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10060670 - 13 Jun 2020
Cited by 7 | Viewed by 3400
Abstract
It is not an exaggerated fact that the semiconductor titanium dioxide (TiO2) has been evolved as a prototypical material to understand the photocatalytic process and has been demonstrated for various photocatalytic applications such as pollutants degradation, water splitting, heavy metal reduction, [...] Read more.
It is not an exaggerated fact that the semiconductor titanium dioxide (TiO2) has been evolved as a prototypical material to understand the photocatalytic process and has been demonstrated for various photocatalytic applications such as pollutants degradation, water splitting, heavy metal reduction, CO2 conversion, N2 fixation, bacterial disinfection, etc [...] Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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Research

Jump to: Editorial, Review

11 pages, 3178 KiB  
Communication
Facile Formation of Anatase Nanoparticles on H-Titanate Nanotubes at Low Temperature for Efficient Visible Light-Driven Degradation of Organic Pollutants
by Weiwei Fu, Zhiqiang Shi, Helong Bai, Jinyu Dai, Zhiming Lu, Feifei Lei, Deguang Zhang, Lun Zhao and Zongtao Zhang
Catalysts 2020, 10(6), 695; https://doi.org/10.3390/catal10060695 - 19 Jun 2020
Cited by 2 | Viewed by 2384
Abstract
Anatase nanoparticles (5–10 nm) generated on H-titanate nanotube surface (H-titanate/anatase) were prepared by an ingenious and simple method. H-titanate tubes were prepared by a hydrothermal reaction of Ti powder in concentrated NaOH solution and an ion exchange process with HNO3 solution. After [...] Read more.
Anatase nanoparticles (5–10 nm) generated on H-titanate nanotube surface (H-titanate/anatase) were prepared by an ingenious and simple method. H-titanate tubes were prepared by a hydrothermal reaction of Ti powder in concentrated NaOH solution and an ion exchange process with HNO3 solution. After that, at a relatively low drying temperature (100 °C), a small quantity of anatase nanoparticles were in-situ formed on the H-titanate tubes surface by a surface dehydration reaction. In-situ transformation can form a strong interface coupling between H-titanate and anatase, which is conducive to accelerating charge transfer and improving its photocatalytic activity. In addition, the smaller average crystal size, the large specific surface areas (BET), the nanotubed and layered structure and the synergistic effect of dual phases would be beneficial to improving the photocatalytic efficiency. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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15 pages, 5399 KiB  
Article
Controllable Fabrication of Heterogeneous p-TiO2 QDs@g-C3N4 p-n Junction for Efficient Photocatalysis
by Songbo Wang, Feifan Wang, Zhiming Su, Xiaoning Wang, Yicheng Han, Lei Zhang, Jun Xiang, Wei Du and Na Tang
Catalysts 2019, 9(5), 439; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9050439 - 10 May 2019
Cited by 25 | Viewed by 3842
Abstract
Photocatalytic technology has been considered to be an ideal approach to solve the energy and environmental crises, and TiO2 is regarded as the most promising photocatalyst. Compared with bare TiO2, TiO2 based p-n heterojunction exhibits a much better performance [...] Read more.
Photocatalytic technology has been considered to be an ideal approach to solve the energy and environmental crises, and TiO2 is regarded as the most promising photocatalyst. Compared with bare TiO2, TiO2 based p-n heterojunction exhibits a much better performance in charge separation, light absorption and photocatalytic activity. Herein, we developed an efficient method to prepare p-type TiO2 quantum dots (QDs) and decorated graphitic carbonitrile (g-C3N4) nanocomposites, while the composition and structure of the TiO2@g-C3N4 were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectroscopy characterizations. The characterization results reveal the surface decorated TiO2 quantum dots is decomposed by titanium glycerolate, which exhibits p-type conductivity. The presence of p-n heterojunction over interface is confirmed, and photoluminescence results indicate a better performance in transfer and separation of photo-generated charge carriers than pure semiconductors and type-II heterojunction. Moreover, the synergy of p-n heterojunction over interface, strong interface interaction, and quantum-size effect significantly contributes to the promoted performance of TiO2 QDs@g-C3N4 composites. As a result, the as-fabricated TiO2 QDs@g-C3N4 composite with a p/n mass ratio of 0.15 exhibits improved photo-reactivity of 4.3-fold and 5.4-fold compared to pure g-C3N4 in degradation of organic pollutant under full solar spectrum and visible light irradiation, respectively. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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10 pages, 5254 KiB  
Article
Improvement of the Photoelectrochemical Performance of TiO2 Nanorod Array by PEDOT and Oxygen Vacancy Co-Modification
by Bin Yang, Guoqiang Chen, Huiwen Tian and Lei Wen
Catalysts 2019, 9(5), 407; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9050407 - 30 Apr 2019
Cited by 7 | Viewed by 2820
Abstract
In this study, oxygen vacancy modified TiO2 nanorod array photoelectrode was prepared by reducing hydrogen atmosphere to increase its free charge carrier density. Subsequently, a p-type conductive poly 3,4-ethylenedioxythiophene (PEDOT) layer was deposited on the surface of oxygen vacancy modified TiO2 [...] Read more.
In this study, oxygen vacancy modified TiO2 nanorod array photoelectrode was prepared by reducing hydrogen atmosphere to increase its free charge carrier density. Subsequently, a p-type conductive poly 3,4-ethylenedioxythiophene (PEDOT) layer was deposited on the surface of oxygen vacancy modified TiO2, to inhibit the surface states. Meanwhile, a p-n heterojunction formed between PEDOT and TiO2 to improve the separation of photo-induced carriers further. The photocurrent of TiO2 nanorod array increased to nearly 0.9 mA/cm2 after the co-modification under standard sunlight illumination, whose value is nearly nine times higher than that of pure TiO2 nanorod array. Thus, this is a promising modification method for TiO2 photoanode photoelectrochemical (PEC) performance improving. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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19 pages, 2205 KiB  
Article
Optimization of Photocatalytic Degradation of Acid Blue 113 and Acid Red 88 Textile Dyes in a UV-C/TiO2 Suspension System: Application of Response Surface Methodology (RSM)
by Soroosh Mortazavian, Ali Saber and David E. James
Catalysts 2019, 9(4), 360; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9040360 - 14 Apr 2019
Cited by 89 | Viewed by 6862
Abstract
Textile industries produce copious amounts of colored wastewater some of which are toxic to humans and aquatic biota. This study investigates optimization of a bench-scale UV-C photocatalytic process using a TiO2 catalyst suspension for degradation of two textile dyes, Acid Blue 113 [...] Read more.
Textile industries produce copious amounts of colored wastewater some of which are toxic to humans and aquatic biota. This study investigates optimization of a bench-scale UV-C photocatalytic process using a TiO2 catalyst suspension for degradation of two textile dyes, Acid Blue 113 (AB 113) and Acid Red 88 (AR 88). From preliminary experiments, appropriate ranges for experimental factors including reaction time, solution pH, initial dye concentration and catalyst dose, were determined for each dye. Response surface methodology (RSM) using a cubic IV optimal design was then used to design the experiments and optimize the process. Analysis of variance (ANOVA) was employed to determine significance of experimental factors and their interactions. Results revealed that among the studied factors, solution pH and initial dye concentration had the strongest effects on degradation rates of AB 113 and AR 88, respectively. Least-squares cubic regression models were generated by step-wise elimination of non-significant (p-value > 0.05) terms from the proposed model. Under optimum treatment conditions, removal efficiencies reached 98.7% for AB 113 and 99.6% for AR 88. Kinetic studies showed that a first-order kinetic model could best describe degradation data for both dyes, with degradation rate constants of k1, AB 113 = 0.048 min−1 and k1, AR 88 = 0.059 min−1. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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15 pages, 3103 KiB  
Article
Facet-Dependent Interfacial Charge Transfer in TiO2/Nitrogen-Doped Graphene Quantum Dots Heterojunctions for Visible-Light Driven Photocatalysis
by Nan-Quan Ou, Hui-Jun Li, Bo-Wen Lyu, Bo-Jie Gui, Xiong Sun, Dong-Jin Qian, Yanlin Jia, Xianying Wang and Junhe Yang
Catalysts 2019, 9(4), 345; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9040345 - 09 Apr 2019
Cited by 34 | Viewed by 4105
Abstract
Interfacial charge transfer is crucial in the efficient conversion of solar energy into fuels and electricity. In this paper, heterojunction composites were fabricated, comprised of anatase TiO2 with different percentages of exposed {101} and {001} facets and nitrogen-doped quantum dots (NGQDs) to [...] Read more.
Interfacial charge transfer is crucial in the efficient conversion of solar energy into fuels and electricity. In this paper, heterojunction composites were fabricated, comprised of anatase TiO2 with different percentages of exposed {101} and {001} facets and nitrogen-doped quantum dots (NGQDs) to enhance the transfer efficiency of photo-excited charge carriers. The photocatalytic performances of all samples were evaluated for RhB degradation under visible light irradiation, and the hybrid containing TiO2 with 56% {001} facets demonstrated the best photocatalytic activity. The excellent photoactivity of TiO2/NGQDs was owed to the synergistic effects of the following factors: (i) The unique chemical features of NGQDs endowed NGQDs with high electronic conductivities and provided its direct contact with the TiO2 surface via forming Ti–O–C chemical bonds. (ii) The co-exposed {101} and {001} facets were beneficial for the separation and transfer of charge carriers in anatase TiO2. (iii) The donor-acceptor interaction between NGQDs and electron-rich {101} facets of TiO2 could remarkably enhance the photocurrent, thus hindering the charge carriers recombination rate. Extensive characterization of their physiochemical properties further showed the synergistic effect of facet-manipulated electron-hole separation in TiO2 and donor-acceptor interaction in graphene quantum dots (GQDs)/TiO2 on photocatalytic activity. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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12 pages, 1750 KiB  
Article
Hydrogen Production from Glycerol Photoreforming on TiO2/HKUST-1 Composites: Effect of Preparation Method
by Fabián M. Martínez, Elim Albiter, Salvador Alfaro, Ana L. Luna, Christophe Colbeau-Justin, José M. Barrera-Andrade, Hynd Remita and Miguel A. Valenzuela
Catalysts 2019, 9(4), 338; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9040338 - 04 Apr 2019
Cited by 20 | Viewed by 4589
Abstract
Coupling metal-organic frameworks (MOFs) with inorganic semiconductors has been successfully tested in a variety of photocatalytic reactions. In this work we present the synthesis of TiO2/HKUST-1 composites by grinding, solvothermal, and chemical methods, using different TiO2 loadings. These composites were [...] Read more.
Coupling metal-organic frameworks (MOFs) with inorganic semiconductors has been successfully tested in a variety of photocatalytic reactions. In this work we present the synthesis of TiO2/HKUST-1 composites by grinding, solvothermal, and chemical methods, using different TiO2 loadings. These composites were used as photocatalysts for hydrogen production by the photoreforming of a glycerol-water mixture under simulated solar light. Several characterization techniques were employed, including X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), infrared spectroscopy (FTIR), and time-resolved microwave conductivity (TRMC). A synergetic effect was observed with all TiO2/HKUST-1 composites (mass ratio TiO2/MOF 1:1), which presented higher photocatalytic activity than that of individual components. These results were explained in terms of an inhibition of the charge carrier (hole-electron) recombination reaction after photoexcitation, favoring the electron transfer from TiO2 to the MOF and creating reversible Cu1+/Cu0 entities useful for hydrogen production. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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13 pages, 2279 KiB  
Article
Synergistic Effect of Photocatalytic Degradation of Hexabromocyclododecane in Water by UV/TiO2/persulfate
by Qiang Li, Lifang Wang, Xuhui Fang, Li Zhang, Jingjiu Li and Hongyong Xie
Catalysts 2019, 9(2), 189; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9020189 - 18 Feb 2019
Cited by 22 | Viewed by 3788
Abstract
In this work, the elimination of hexabromocyclododecane (HBCD) is explored by using photodegradation of the UV/TiO2 system, the UV/potassium persulfate (KPS) system, and the homo/heterogeneous UV/TiO2/KPS system. The experimental results show that the dosages of TiO2 and potassium persulfate [...] Read more.
In this work, the elimination of hexabromocyclododecane (HBCD) is explored by using photodegradation of the UV/TiO2 system, the UV/potassium persulfate (KPS) system, and the homo/heterogeneous UV/TiO2/KPS system. The experimental results show that the dosages of TiO2 and potassium persulfate have optimum values to increase the degradation degree. HBCD can be almost completely degraded and 74.3% of the total bromine content is achieved in the UV/TiO2/KPS homo/heterogeneous photocatalysis, much more than in the UV/persulfate system and the UV/TiO2 system. Roles of radicals SO4•− and OH• in the photocatalysis systems are discussed based on experimental measurements. The high yield of the concentration of bromide ions and decreased pH value indicates that synergistic effects exist in the UV/TiO2/KPS homo/heterogeneous photocatalysis, which can mineralize HBCD into inorganic small molecules like carboxylic acids, CO2 and H2O, thus much less intermediates are formed. The possible pathways of degradation of HBCD in the UV/TiO2/KPS system were also analyzed by GC/MS. This work will have practical application potential in the fields of pollution control and environmental management. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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10 pages, 1099 KiB  
Article
Photocatalytic Degradation of Microcystins by TiO2 Using UV-LED Controlled Periodic Illumination
by Olivia M. Schneider, Robert Liang, Leslie Bragg, Ivana Jaciw-Zurakowsky, Azar Fattahi, Shasvat Rathod, Peng Peng, Mark R. Servos and Y. Norman Zhou
Catalysts 2019, 9(2), 181; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9020181 - 14 Feb 2019
Cited by 24 | Viewed by 5026
Abstract
Toxic microcystins (MCs) produced by freshwater cyanobacteria such as Microcystis aeruginosa are of concern because of their negative health and economic impacts globally. An advanced oxidation process using UV/TiO2 offers a promising treatment option for hazardous organic pollutants such as microcystins. The [...] Read more.
Toxic microcystins (MCs) produced by freshwater cyanobacteria such as Microcystis aeruginosa are of concern because of their negative health and economic impacts globally. An advanced oxidation process using UV/TiO2 offers a promising treatment option for hazardous organic pollutants such as microcystins. The following work details the successful degradation of MC-LA, MC-LR, and MC-RR using a porous titanium–titanium dioxide (PTT) membrane under UV-LED light. Microcystin quantitation was achieved by sample concentration and subsequent LC–MS/MS analysis. The PTT membrane offers a treatment option that eliminates the need for the additional filtration or separation steps required for traditional catalysts. Controlled periodic illumination was successfully used to decrease the total light exposure time and improve the photonic efficiency for a more cost-effective treatment system. Individual degradation rates were influenced by electrostatic forces between the catalyst and differently charged microcystins, which can potentially be adjusted by modifying the solution pH and the catalyst’s isoelectric point. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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15 pages, 4419 KiB  
Article
Development of TiO2-Carbon Composite Acid Catalyst for Dehydration of Fructose to 5-Hydroxymethylfurfural
by Morongwa Martha Songo, Richard Moutloali and Suprakas Sinha Ray
Catalysts 2019, 9(2), 126; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9020126 - 31 Jan 2019
Cited by 21 | Viewed by 3100
Abstract
A TiO2-Carbon (TiO2C) composite was prepared using the microwave-assisted method and sulfonated using fuming sulfuric acid to produce a TiO2C solid acid catalyst. The prepared solid acid catalyst was characterised using scanning electron microscopy, Brunauer-Emmett-Teller analysis, Fourier [...] Read more.
A TiO2-Carbon (TiO2C) composite was prepared using the microwave-assisted method and sulfonated using fuming sulfuric acid to produce a TiO2C solid acid catalyst. The prepared solid acid catalyst was characterised using scanning electron microscopy, Brunauer-Emmett-Teller analysis, Fourier transform infrared spectroscopy, and X-ray diffraction. Crystallinity analysis confirmed that TiO2C has an anatase structure, while analysis of its morphology showed a combination of spheres and particles with a diameter of 50 nm. The TiO2C solid acid catalyst was tested for use in the catalytic dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The effect of reaction time, reaction temperature, catalyst dosage, and solvent were investigated against the 5-HMF yield. The 5-HMF yield was found to be 90% under optimum conditions. The solid acid catalyst is very stable and can be reused for four catalytic cycles. Hence, the material has great potential for use in industrial applications and can be used for the direct conversion of fructose to 5-HMF because of its high activity and high reusability. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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10 pages, 3240 KiB  
Article
Bleached Wood Supports for Floatable, Recyclable, and Efficient Three Dimensional Photocatalyst
by Yuming He, Huayang Li, Xuelian Guo and Rongbo Zheng
Catalysts 2019, 9(2), 115; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9020115 - 26 Jan 2019
Cited by 12 | Viewed by 2445
Abstract
To suppress the agglomeration of a photocatalyst, facilitate its recovery, and avoid photolysis of dyes, various support materials such as ceramic, carbon, and polymer have been investigated. However, these support materials pose the following additional challenges: ceramic supports will settle down at the [...] Read more.
To suppress the agglomeration of a photocatalyst, facilitate its recovery, and avoid photolysis of dyes, various support materials such as ceramic, carbon, and polymer have been investigated. However, these support materials pose the following additional challenges: ceramic supports will settle down at the bottom of their container due to their high density, while the carbon support will absorb the UV-vis light for its black color. Herein, we propose a floatable, UV transmitting, mesoporous bleached wood with most lignin removal to support P25 nanoparticles (BP-wood) that can effectively, recyclable, three dimensional (3D) photocatalytic degrade dyes such as methylene blue (MB) under ambient sunlight. The BP-wood has the following advantages: (1) The delignification makes the BP-wood more porous to not only quickly transport MB solutions upstream to the top surface, but is also decorated with P25 nanoparticles on the cell wall to form a 3D photocatalyst. (2) The delignification endows the BP-wood with good UV transmittance to undergo 3D photocatalytic degradation under sunlight. (3) It can float on the surface of the MB solution to capture more sunlight to enhance the photodegradation efficiency by suppressing the photolysis of MB. (4) It has comparable or even better photocatalytic degradation of 40 mg/L and 60 mg/L MB than that of P25 nanoparticles suspension. (5) It is green, recyclable, and scalable. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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15 pages, 4504 KiB  
Article
Ru-Ti Oxide Based Catalysts for HCl Oxidation: The Favorable Oxygen Species and Influence of Ce Additive
by Jian Shi, Feng Hui, Jun Yuan, Qinwei Yu, Suning Mei, Qian Zhang, Jialin Li, Weiqiang Wang, Jianming Yang and Jian Lu
Catalysts 2019, 9(2), 108; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9020108 - 22 Jan 2019
Cited by 29 | Viewed by 4180
Abstract
Several Ru-Ti oxide-based catalysts were investigated for the catalytic oxidation of HCl to Cl2 in this work. The active component RuO2 was loaded on different titanium-containing supports by a facile wetness impregnation method. The Ru-Ti oxide based catalysts were characterized by [...] Read more.
Several Ru-Ti oxide-based catalysts were investigated for the catalytic oxidation of HCl to Cl2 in this work. The active component RuO2 was loaded on different titanium-containing supports by a facile wetness impregnation method. The Ru-Ti oxide based catalysts were characterized by XRD, N2 sorption, SEM, TEM, H2-TPR, XPS, and Raman, which is correlated with the catalytic tests. Rutile TiO2 was confirmed as the optimal support even though it has a low specific surface area. In addition to the interfacial epitaxial lattice matching and epitaxy, the extraordinary performance of Ru-Ti rutile oxide could also be attributed to the favorable oxygen species on Ru sites and specific active phase-support interactions. On the other hand, the influence of additive Ce on the RuO2/TiO2-rutile was studied. The incorporation of Ce by varied methods resulted in further oxidation of RuO2 into RuO2δ+ and a modification of the support structure. The amount of favorable oxygen species on the surface was decreased. As a result, the Deacon activity was lowered. It was demonstrated that the surface oxygen species and specific interactions of the Ru-Ti rutile oxide were critical to HCl oxidation. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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16 pages, 3739 KiB  
Article
Adsorption and Photocatalytic Decomposition of Gaseous 2-Propanol Using TiO2-Coated Porous Glass Fiber Cloth
by Sayaka Yanagida, Kentaro Hirayama, Kenichiro Iwasaki and Atsuo Yasumori
Catalysts 2019, 9(1), 82; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9010082 - 14 Jan 2019
Cited by 8 | Viewed by 3939
Abstract
Combinations of TiO2 photocatalysts and various adsorbents have been extensively investigated for eliminating volatile organic compounds (VOCs) at low concentrations. Herein, TiO2 and porous glass cloth composites were prepared by acid leaching and subsequent TiO2 dip-coating of the electrically applied [...] Read more.
Combinations of TiO2 photocatalysts and various adsorbents have been extensively investigated for eliminating volatile organic compounds (VOCs) at low concentrations. Herein, TiO2 and porous glass cloth composites were prepared by acid leaching and subsequent TiO2 dip-coating of the electrically applied glass (E-glass) cloth, and its adsorption and photocatalytic ability were investigated. Acid leaching increased the specific surface area of the E-glass cloth from 1 to 430 m2/g while maintaining sufficient mechanical strength for supporting TiO2. Further, the specific surface area remained large (290 m2/g) after TiO2 coating. In the photocatalytic decomposition of gaseous 2-propanol, the TiO2-coated porous glass cloth exhibited higher adsorption and photocatalytic decomposition ability than those exhibited by the TiO2-coated, non-porous glass cloth. The porous composite limited desorption of acetone, which is a decomposition intermediate of 2-propanol, until 2-propanol was completely decomposed to CO2. The CO2 generation rate was affected by the temperature condition (15 or 35 °C) and the water content (2 or 18 mg/L); the latter also influenced 2-propanol adsorption in photocatalytic decomposition. Both the conditions may change the diffusion and adsorption behavior of 2-propanol in the porous composite. As demonstrated by its high adsorption and photocatalytic ability, the composite (TiO2 and porous glass cloth) effectively eliminates VOCs, while decreasing the emission of harmful intermediates. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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12 pages, 3115 KiB  
Article
Enhanced Photocatalytic Reduction of Cr(VI) by Combined Magnetic TiO2-Based NFs and Ammonium Oxalate Hole Scavengers
by Yin-Hsuan Chang and Ming-Chung Wu
Catalysts 2019, 9(1), 72; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9010072 - 10 Jan 2019
Cited by 22 | Viewed by 4785
Abstract
Heavy metal pollution of wastewater with coexisting organic contaminants has become a serious threat to human survival and development. In particular, hexavalent chromium, which is released into industrial wastewater, is both toxic and carcinogenic. TiO2 photocatalysts have attracted much attention due to [...] Read more.
Heavy metal pollution of wastewater with coexisting organic contaminants has become a serious threat to human survival and development. In particular, hexavalent chromium, which is released into industrial wastewater, is both toxic and carcinogenic. TiO2 photocatalysts have attracted much attention due to their potential photodegradation and photoreduction abilities. Though TiO2 demonstrates high photocatalytic performance, it is a difficult material to recycle after the photocatalytic reaction. Considering the secondary pollution caused by the photocatalysts, in this study we prepared Ag/Fe3O4/TiO2 nanofibers (NFs) that could be magnetically separated using hydrothermal synthesis, which was considered a benign and effective resolution. For the photocatalytic test, the removal of Cr(VI) was carried out by Ag/Fe3O4/TiO2 nanofibers combined with ammonium oxalate (AO). AO acted as a hole scavenger to enhance the electron-hole separation ability, thereby dramatically enhancing the photoreduction efficiency of Cr(VI). The reaction rate constant for Ag/Fe3O4/TiO2 NFs in the binary system reached 0.260 min−1, 6.95 times of that of Ag/Fe3O4/TiO2 NFs in a single system (0.038 min−1). The optimized Ag/Fe3O4/TiO2 NFs exhibited high efficiency and maintained their photoreduction efficiency at 90% with a recyclability of 87% after five cycles. Hence, taking into account the high magnetic separation behavior, Ag/Fe3O4/TiO2 NFs with a high recycling capability are a potential photocatalyst for wastewater treatment. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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22 pages, 6068 KiB  
Article
Photocatalytic Hydrogen Production Under Near-UV Using Pd-Doped Mesoporous TiO2 and Ethanol as Organic Scavenger
by Bianca Rusinque, Salvador Escobedo and Hugo de Lasa
Catalysts 2019, 9(1), 33; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9010033 - 02 Jan 2019
Cited by 20 | Viewed by 5809
Abstract
Photocatalysis can be used advantageously for hydrogen production using a light source (near-UV light), a noble metal-doped semiconductor and an organic scavenger (2.0 v/v% ethanol). With this end, palladium was doped on TiO2 photocatalysts at different metal loadings (0.25 to 5.00 wt%). [...] Read more.
Photocatalysis can be used advantageously for hydrogen production using a light source (near-UV light), a noble metal-doped semiconductor and an organic scavenger (2.0 v/v% ethanol). With this end, palladium was doped on TiO2 photocatalysts at different metal loadings (0.25 to 5.00 wt%). Photocatalysts were synthetized using a sol-gel method enhancing morphological properties with a soft template precursor. Experiments were carried out in the Photo-CREC Water II reactor system developed at CREC-UWO (Chemical Reactor Engineering Centre- The University of Western Ontario) Canada. This novel unit offers hydrogen storage and symmetrical irradiation allowing precise irradiation measurements for macroscopic energy balances. Hydrogen production rates followed in all cases a zero-order reaction, with quantum yields as high as 30.8%. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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12 pages, 2884 KiB  
Article
Comparing the Efficiency of N-Doped TiO2 and N-Doped Bi2MoO6 Photo Catalysts for MB and Lignin Photodegradation
by Ricardo Rangel, Verónica Janneth Cedeño, Jaime Espino, Pascual Bartolo-Pérez, Geonel Rodríguez-Gattorno and Juan José Alvarado-Gil
Catalysts 2018, 8(12), 668; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8120668 - 19 Dec 2018
Cited by 22 | Viewed by 4987
Abstract
In this study, we tested the efficiency of nitrogen-doped titanium dioxide (N-TiO2) and nitrogen-doped bismuth molybdate (N-Bi2MoO6) compounds as photocatalysts capable of degrading methylene blue and lignin molecules under irradiation with ultraviolet (UV) and visible light (VIS). [...] Read more.
In this study, we tested the efficiency of nitrogen-doped titanium dioxide (N-TiO2) and nitrogen-doped bismuth molybdate (N-Bi2MoO6) compounds as photocatalysts capable of degrading methylene blue and lignin molecules under irradiation with ultraviolet (UV) and visible light (VIS). Moreover, we compared TiO2 and Bi2MoO6 catalysts with N-TiO2 and N-Bi2MoO6 compounds using chemical coprecipitation. The catalysts were prepared starting from Ti(OCH2CH2CH3)4, Bi(NO3)3·5H2O, and (NH4)6Mo7O24 reagents. N-doping was achieved in a continuous reflux system, using ethylene diamine as a nitrogen source. The resulting materials were characterized using Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Additionally, we observed the decrease in particle size after processing the compounds in the reflux system. The results regarding photocatalytic degradation tests show a remarkable effect for nitrogen doped samples, achieving 90% of lignin degradation. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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12 pages, 2523 KiB  
Article
Highly Selective Photocatalytic Reduction of o-Dinitrobenzene to o-Phenylenediamine over Non-Metal-Doped TiO2 under Simulated Solar Light Irradiation
by Hamza M. El-Hosainy, Said M. El-Sheikh, Adel A. Ismail, Amer Hakki, Ralf Dillert, Hamada M. Killa, Ibrahim A. Ibrahim and Detelf W. Bahnemann
Catalysts 2018, 8(12), 641; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8120641 - 09 Dec 2018
Cited by 12 | Viewed by 5129
Abstract
Photocatalytic reduction and hydrogenation reaction of o-dinitrobenzene in the presence of oxalic acid over anatase-brookite biphasic TiO2 and non-metal-doped anatase-brookite biphasic TiO2 photocatalysts under solar simulated light was investigated. Compared with commercial P25 TiO2, the prepared un-doped and doped [...] Read more.
Photocatalytic reduction and hydrogenation reaction of o-dinitrobenzene in the presence of oxalic acid over anatase-brookite biphasic TiO2 and non-metal-doped anatase-brookite biphasic TiO2 photocatalysts under solar simulated light was investigated. Compared with commercial P25 TiO2, the prepared un-doped and doped anatase-brookite biphasic TiO2 exhibited a high selectivity towards the formation of o-nitroaniline (85.5%) and o-phenylenediamine ~97%, respectively. The doped anatase-brookite biphasic TiO2 has promoted photocatalytic reduction of the two-nitro groups of o-dinitrobenzene to the corresponding o-phenylenediamine with very high yield ~97%. Electron paramagnetic resonance analysis, Transient Absorption Spectroscopy (TAS) and Photoluminescence analysis (PL) were performed to determine the distribution of defects and the fluorescence lifetime of the charge carriers for un-doped and doped photocatalysts. The superiority of the doped TiO2 photocatalysts is accredited to the creation of new dopants (C, N, and S) as hole traps, the formation of long-lived Ti3+ defects which leads to an increase in the fluorescence lifetime of the formed charge carriers. The schematic diagram of the photocatalytic reduction of o-dinitrobenzene using the doped TiO2 under solar light was also illustrated in detail. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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20 pages, 4471 KiB  
Article
Enhanced Photocatalytic Activity of Titania by Co-Doping with Mo and W
by Osmín Avilés-García, Jaime Espino-Valencia, Rubí Romero-Romero, José Luis Rico-Cerda, Manuel Arroyo-Albiter, Dora Alicia Solís-Casados and Reyna Natividad-Rangel
Catalysts 2018, 8(12), 631; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8120631 - 06 Dec 2018
Cited by 41 | Viewed by 5084
Abstract
Various W and Mo co-doped titanium dioxide (TiO2) materials were obtained through the EISA (Evaporation-Induced Self-Assembly) method and then tested as photocatalysts in the degradation of 4-chlorophenol. The synthesized materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, [...] Read more.
Various W and Mo co-doped titanium dioxide (TiO2) materials were obtained through the EISA (Evaporation-Induced Self-Assembly) method and then tested as photocatalysts in the degradation of 4-chlorophenol. The synthesized materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy (RS), N2 physisorption, UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results showed that the W-Mo-TiO2 catalysts have a high surface area of about 191 m2/g, and the presence of an anatase crystalline phase. The co-doped materials exhibited smaller crystallite sizes than those with one dopant, since the crystallinity is inhibited by the presence of both species. In addition, tungsten and molybdenum dopants are distributed and are incorporated into the anatase structure of TiO2, due to changes in red parameters and lattice expansion. Under our experimental conditions, the co-doped TiO2 catalyst presented 46% more 4-chlorophenol degradation than Degussa P25. The incorporation of two dopant cations in titania improved its photocatalytic performance, which was attributed to a cooperative effect by decreasing the recombination of photogenerated charges, high radiation absorption capacity, high surface areas, and low crystallinity. When TiO2 is co-doped with the same amount of both cations (1 wt.%), the highest degradation and mineralization (97% and 74%, respectively) is achieved. Quinones were the main intermediates in the 4-chlorophenol oxidation by W-Mo-TiO2 and 1,2,4-benzenetriol was incompletely degraded. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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24 pages, 19869 KiB  
Article
Photocatalytic Degradation of Estriol Using Iron-Doped TiO2 under High and Low UV Irradiation
by Irwing M. Ramírez-Sánchez and Erick R. Bandala
Catalysts 2018, 8(12), 625; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8120625 - 05 Dec 2018
Cited by 30 | Viewed by 4596
Abstract
Iron-doped TiO2 nanoparticles (Fe-TiO2) were synthesized and photocatalitically investigated under high and low fluence values of UV radiation. The Fe-TiO2 physical characterization was performed using X-ray Powder Diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Transmission Electron Microscopy (TEM), Scanning [...] Read more.
Iron-doped TiO2 nanoparticles (Fe-TiO2) were synthesized and photocatalitically investigated under high and low fluence values of UV radiation. The Fe-TiO2 physical characterization was performed using X-ray Powder Diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Diffuse Reflectance Spectroscopy (DRS), and X-ray Photoelectron Spectroscopy (XPS). The XPS evidenced that the ferric ion (Fe3+) was in the TiO2 lattice and unintentionally added co-dopants were also present because of the precursors of the synthetic method. The Fe3+ concentration played a key role in the photocatalytic generation of hydroxyl radicals (•OH) and estriol (E3) degradation. Fe-TiO2 accomplished E3 degradation, and it was found that the catalyst with 0.3 at.% content of Fe (0.3 Fe-TiO2) enhanced the photocatalytic activity under low UV irradiation compared with TiO2 without intentionally added Fe (zero-iron TiO2) and Aeroxide® TiO2 P25. Furthermore, the enhanced photocatalytic activity of 0.3 Fe-TiO2 under low UV irradiation may have applications when radiation intensity must be controlled, as in medical applications, or when strong UV absorbing species are present in water. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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15 pages, 3061 KiB  
Article
Mechanistic Study on Facet-Dependent Deposition of Metal Nanoparticles on Decahedral-Shaped Anatase Titania Photocatalyst Particles
by Kenta Kobayashi, Mai Takashima, Mai Takase and Bunsho Ohtani
Catalysts 2018, 8(11), 542; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8110542 - 13 Nov 2018
Cited by 11 | Viewed by 4006
Abstract
Facet-selective gold or platinum-nanoparticle deposition on decahedral-shaped anatase titania particles (DAPs) exposing {001} and {101} facets via photodeposition (PD) from metal-complex sources was reexamined using DAPs prepared with gas-phase reaction of titanium (IV) chloride and oxygen by quantitatively evaluating the area deposition density [...] Read more.
Facet-selective gold or platinum-nanoparticle deposition on decahedral-shaped anatase titania particles (DAPs) exposing {001} and {101} facets via photodeposition (PD) from metal-complex sources was reexamined using DAPs prepared with gas-phase reaction of titanium (IV) chloride and oxygen by quantitatively evaluating the area deposition density on {001} and {101} and comparing with the results of deposition from colloidal metal particles in the dark (CDD) or under photoirradiation (CDL). The observed facet selectivity, more or less {101} preferable, depended mainly on pH of the reaction suspensions and was almost non-selective at low pH regardless of the deposition method, PD or CDL, and the metal-source materials. Based on the results, the present authors propose that facet selectivity is attributable to surface charges (zeta potential) depending on the kind of facets, {001} and {101}, and pH of the reaction mixture and that this concept can explain the observed facet selectivity and possibly the reported facet selectivity without taking into account facet-selective reaction of photoexcited electrons and positive holes on {101} and {001} facets, respectively. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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7 pages, 3117 KiB  
Article
Solid-Phase Photocatalytic Degradation of Polyvinyl Borate
by Hafize Nagehan Koysuren
Catalysts 2018, 8(11), 499; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8110499 - 26 Oct 2018
Cited by 10 | Viewed by 2536
Abstract
In this study, polymer composites based on polyvinyl borate (PVB) with titanium dioxide (TiO2) nanoparticles were prepared through the condensation reaction of polyvinyl alcohol and boric acid in the presence of TiO2 nanoparticles. The solid-phase photocatalytic degradation of the polymer [...] Read more.
In this study, polymer composites based on polyvinyl borate (PVB) with titanium dioxide (TiO2) nanoparticles were prepared through the condensation reaction of polyvinyl alcohol and boric acid in the presence of TiO2 nanoparticles. The solid-phase photocatalytic degradation of the polymer composites under UV light irradiation was investigated and compared with that of the pure PVB with the aid of weight loss measurements. The introduction of the photocatalyst nanoparticles in PVB enhanced the solid-phase photocatalytic degradation of the polymer matrix under UV light irradiation. The structural and morphological properties of PVB/TiO2 composites were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and UV-Vis spectroscopy, respectively. FTIR analysis revealed that PVB synthesis was successfully carried out in the presence of the photocatalyst nanoparticles. According to the morphological analyses, TiO2 nanoparticles were well dispersed in the PVB matrix. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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11 pages, 4156 KiB  
Article
The Synergistic Effect of Pyridinic Nitrogen and Graphitic Nitrogen of Nitrogen-Doped Graphene Quantum Dots for Enhanced TiO2 Nanocomposites’ Photocatalytic Performance
by Fei Li, Ming Li, Yi Luo, Ming Li, Xinyu Li, Jiye Zhang and Liang Wang
Catalysts 2018, 8(10), 438; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8100438 - 04 Oct 2018
Cited by 13 | Viewed by 3871
Abstract
In this study, nitrogen-doped graphene quantum dots (N-GQDs) and a TiO2 nanocomposite were synthesized using a simple hydrothermal route. Ammonia water was used as a nitrogen source to prepare the N-GQDs. When optically characterized by UV-vis, N-GQDs reveal stronger absorption peaks in [...] Read more.
In this study, nitrogen-doped graphene quantum dots (N-GQDs) and a TiO2 nanocomposite were synthesized using a simple hydrothermal route. Ammonia water was used as a nitrogen source to prepare the N-GQDs. When optically characterized by UV-vis, N-GQDs reveal stronger absorption peaks in the range of ultraviolet (UV) light than graphene quantum dots (GQDs). In comparison with GQDs/TiO2 and pure TiO2, the N-GQDs/TiO2 have significantly improved photocatalytic performance. In particular, it was found that, when the added amount of ammonia water was 50 mL, the content of pyridinic N and graphitic N were as high as 22.47% and 31.44%, respectively. Most important, the photocatalytic activity of N-GQDs/TiO2-50 was about 95% after 12 min. The results illustrated that pyridinic N and graphitic N play a significant role in photocatalytic performance. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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10 pages, 1662 KiB  
Communication
Improving Interfacial Charge-Transfer Transitions in Nb-Doped TiO2 Electrodes with 7,7,8,8-Tetracyanoquinodimethane
by Reo Eguchi, Yuya Takekuma, Tsuyoshi Ochiai and Morio Nagata
Catalysts 2018, 8(9), 367; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8090367 - 30 Aug 2018
Cited by 3 | Viewed by 3256
Abstract
Interfacial charge-transfer (ICT) transitions involved in charge-separation mechanisms are expected to enable efficient photovoltaic conversions through one-step charge-separation processes. With this in mind, the charge-transfer complex fabricated from TiO2 nanoparticles and 7,7,8,8-tetracyanoquinodimethane (TCNQ) has been applied to dye-sensitized solar cells. However, rapid [...] Read more.
Interfacial charge-transfer (ICT) transitions involved in charge-separation mechanisms are expected to enable efficient photovoltaic conversions through one-step charge-separation processes. With this in mind, the charge-transfer complex fabricated from TiO2 nanoparticles and 7,7,8,8-tetracyanoquinodimethane (TCNQ) has been applied to dye-sensitized solar cells. However, rapid carrier recombination from the conduction band of TiO2 to the highest occupied molecular orbital (HOMO) of TCNQ remains a major issue for this complex. In this study, to inhibit surface-complex recombinations, we prepared Nb-doped TiO2 nanoparticles with different atomic ratios for enhanced electron transport. To investigate the effects of doping on electron injection through ICT transitions, these materials were examined as photoelectrodes. When TiO2 was doped with 1.5 mol % Nb, the Fermi level of the TiO2 electrode shifted toward the conduction band minimum, which improved electron back-contact toward the HOMO of TCNQ. The enhancement in electron transport led to increases in both short circuit current and open circuit voltage, resulting in a slight (1.1% to 1.3%) improvement in photovoltaic conversion efficiency compared to undoped TiO2. Such control of electron transport within the photoelectrode is attributed to improvements in electron injection through ICT transitions. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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10 pages, 2536 KiB  
Article
Photocatalytic Antibacterial Effectiveness of Cu-Doped TiO2 Thin Film Prepared via the Peroxo Sol-Gel Method
by Benjawan Moongraksathum, Jun-Ya Shang and Yu-Wen Chen
Catalysts 2018, 8(9), 352; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8090352 - 27 Aug 2018
Cited by 40 | Viewed by 5521
Abstract
Cu-doped titanium dioxide thin films (Cu/TiO2) were prepared on glass substrate via peroxo sol-gel method and dip-coating process with no subsequent calcination process for the degradation of organic dye and use as an antibacterial agent. The as-prepared materials were characterised using [...] Read more.
Cu-doped titanium dioxide thin films (Cu/TiO2) were prepared on glass substrate via peroxo sol-gel method and dip-coating process with no subsequent calcination process for the degradation of organic dye and use as an antibacterial agent. The as-prepared materials were characterised using transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). For photocatalytic degradation of methylene blue in water, the samples were subjected to Ultraviolet C (UVC) and visible light irradiation. Degraded methylene blue concentration was measured using UV-Vis spectrophotometer. The antibacterial activities of the samples were tested against the gram-negative bacteria Escherichia coli (ATCC25922). Copper species were present in the form of CuO on the surface of modified TiO2 particles, which was confirmed using TEM and XPS. The optimal observed Cu/TiO2 weight ratio of 0.5 represents the highest photocatalytic activities under both UVC and visible light irradiation. Moreover, the same composition remarkably exhibited high antibacterial effectiveness against E. coli after illumination with ultraviolet A. The presence of CuO on TiO2 significantly enhanced photocatalytic activities. Therefore, active Cu-doped TiO2 can be used as a multipurpose coating material. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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14 pages, 3602 KiB  
Article
Modification to L-H Kinetics Model and Its Application in the Investigation on Photodegradation of Gaseous Benzene by Nitrogen-Doped TiO2
by Peng Sun, Jun Zhang, Wenxiu Liu, Qi Wang and Wenbin Cao
Catalysts 2018, 8(8), 326; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8080326 - 09 Aug 2018
Cited by 28 | Viewed by 4712
Abstract
In this paper, the Langmuir-Hinshelwood (L-H) model has been used to investigate the kinetics of photodegradation of gaseous benzene by nitrogen-doped TiO2 (N-TiO2) at 25 °C under visible light irradiation. Experimental results show that the photoreaction coefficient kpm increased [...] Read more.
In this paper, the Langmuir-Hinshelwood (L-H) model has been used to investigate the kinetics of photodegradation of gaseous benzene by nitrogen-doped TiO2 (N-TiO2) at 25 °C under visible light irradiation. Experimental results show that the photoreaction coefficient kpm increased from 3.992 × 10−6 mol·kg−1·s−1 to 11.55 × 10−6 mol·kg−1·s−1 along with increasing illumination intensity. However, the adsorption equilibrium constant KL decreased from 1139 to 597 m3·mol−1 when the illumination intensity increased from 36.7 × 104 lx to 75.1 × 104 lx, whereas it was 2761 m3·mol−1 in the absence of light. This is contrary to the fact that KL should be a constant if the temperature was fixed. This phenomenon can be attributed to the breaking of the adsorption-desorption equilibrium by photocatalytically decomposition. To compensate for the disequilibrium of the adsorption-desorption process, photoreaction coefficient kpm was introduced to the expression of KL and the compensation form was denoted as Km. KL is an indicator of the adsorption capacity of TiO2 while Km is only an indicator of the coverage ratio of TiO2 surface. The modified L-H model has been experimentally verified so it is expected to be used to predict the kinetics of the photocatalytic degradation of gaseous benzene. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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Review

Jump to: Editorial, Research

32 pages, 9254 KiB  
Review
Insights into the TiO2-Based Photocatalytic Systems and Their Mechanisms
by Mohan Sakar, Ravikumar Mithun Prakash and Trong-On Do
Catalysts 2019, 9(8), 680; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9080680 - 09 Aug 2019
Cited by 78 | Viewed by 12434
Abstract
Photocatalysis is a multifunctional phenomenon that can be employed for energy applications such as H2 production, CO2 reduction into fuels, and environmental applications such as pollutant degradations, antibacterial disinfection, etc. In this direction, it is not an exaggerated fact that TiO [...] Read more.
Photocatalysis is a multifunctional phenomenon that can be employed for energy applications such as H2 production, CO2 reduction into fuels, and environmental applications such as pollutant degradations, antibacterial disinfection, etc. In this direction, it is not an exaggerated fact that TiO2 is blooming in the field of photocatalysis, which is largely explored for various photocatalytic applications. The deeper understanding of TiO2 photocatalysis has led to the design of new photocatalytic materials with multiple functionalities. Accordingly, this paper exclusively reviews the recent developments in the modification of TiO2 photocatalyst towards the understanding of its photocatalytic mechanisms. These modifications generally involve the physical and chemical changes in TiO2 such as anisotropic structuring and integration with other metal oxides, plasmonic materials, carbon-based materials, etc. Such modifications essentially lead to the changes in the energy structure of TiO2 that largely boosts up the photocatalytic process via enhancing the band structure alignments, visible light absorption, carrier separation, and transportation in the system. For instance, the ability to align the band structure in TiO2 makes it suitable for multiple photocatalytic processes such as degradation of various pollutants, H2 production, CO2 conversion, etc. For these reasons, TiO2 can be realized as a prototypical photocatalyst, which paves ways to develop new photocatalytic materials in the field. In this context, this review paper sheds light into the emerging trends in TiO2 in terms of its modifications towards multifunctional photocatalytic applications. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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22 pages, 7541 KiB  
Review
Titanium-Dioxide-Based Visible-Light-Sensitive Photocatalysis: Mechanistic Insight and Applications
by Shinya Higashimoto
Catalysts 2019, 9(2), 201; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9020201 - 22 Feb 2019
Cited by 67 | Viewed by 9189
Abstract
Titanium dioxide (TiO2) is one of the most practical and prevalent photo-functional materials. Many researchers have endeavored to design several types of visible-light-responsive photocatalysts. In particular, TiO2-based photocatalysts operating under visible light should be urgently designed and developed, in [...] Read more.
Titanium dioxide (TiO2) is one of the most practical and prevalent photo-functional materials. Many researchers have endeavored to design several types of visible-light-responsive photocatalysts. In particular, TiO2-based photocatalysts operating under visible light should be urgently designed and developed, in order to take advantage of the unlimited solar light available. Herein, we review recent advances of TiO2-based visible-light-sensitive photocatalysts, classified by the origins of charge separation photo-induced in (1) bulk impurity (N-doping), (2) hetero-junction of metal (Au NPs), and (3) interfacial surface complexes (ISC) and their related photocatalysts. These photocatalysts have demonstrated useful applications, such as photocatalytic mineralization of toxic agents in the polluted atmosphere and water, photocatalytic organic synthesis, and artificial photosynthesis. We wish to provide comprehension and enlightenment of modification strategies and mechanistic insight, and to inspire future work. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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32 pages, 8851 KiB  
Review
Titanium Dioxide: From Engineering to Applications
by Xiaolan Kang, Sihang Liu, Zideng Dai, Yunping He, Xuezhi Song and Zhenquan Tan
Catalysts 2019, 9(2), 191; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9020191 - 19 Feb 2019
Cited by 282 | Viewed by 20336
Abstract
Titanium dioxide (TiO2) nanomaterials have garnered extensive scientific interest since 1972 and have been widely used in many areas, such as sustainable energy generation and the removal of environmental pollutants. Although TiO2 possesses the desired performance in utilizing ultraviolet light, [...] Read more.
Titanium dioxide (TiO2) nanomaterials have garnered extensive scientific interest since 1972 and have been widely used in many areas, such as sustainable energy generation and the removal of environmental pollutants. Although TiO2 possesses the desired performance in utilizing ultraviolet light, its overall solar activity is still very limited because of a wide bandgap (3.0–3.2 eV) that cannot make use of visible light or light of longer wavelength. This phenomenon is a deficiency for TiO2 with respect to its potential application in visible light photocatalysis and photoelectrochemical devices, as well as photovoltaics and sensors. The high overpotential, sluggish migration, and rapid recombination of photogenerated electron/hole pairs are crucial factors that restrict further application of TiO2. Recently, a broad range of research efforts has been devoted to enhancing the optical and electrical properties of TiO2, resulting in improved photocatalytic activity. This review mainly outlines state-of-the-art modification strategies in optimizing the photocatalytic performance of TiO2, including the introduction of intrinsic defects and foreign species into the TiO2 lattice, morphology and crystal facet control, and the development of unique mesocrystal structures. The band structures, electronic properties, and chemical features of the modified TiO2 nanomaterials are clarified in detail along with details regarding their photocatalytic performance and various applications. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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27 pages, 7168 KiB  
Review
Titanium Dioxide (TiO2) Mesocrystals: Synthesis, Growth Mechanisms and Photocatalytic Properties
by Boxue Zhang, Shengxin Cao, Meiqi Du, Xiaozhou Ye, Yun Wang and Jianfeng Ye
Catalysts 2019, 9(1), 91; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9010091 - 16 Jan 2019
Cited by 52 | Viewed by 7585
Abstract
Hierarchical TiO2 superstructures with desired architectures and intriguing physico-chemical properties are considered to be one of the most promising candidates for solving the serious issues related to global energy exhaustion as well as environmental deterioration via the well-known photocatalytic process. In particular, [...] Read more.
Hierarchical TiO2 superstructures with desired architectures and intriguing physico-chemical properties are considered to be one of the most promising candidates for solving the serious issues related to global energy exhaustion as well as environmental deterioration via the well-known photocatalytic process. In particular, TiO2 mesocrystals, which are built from TiO2 nanocrystal building blocks in the same crystallographical orientation, have attracted intensive research interest in the area of photocatalysis owing to their distinctive structural properties such as high crystallinity, high specific surface area, and single-crystal-like nature. The deeper understanding of TiO2 mesocrystals-based photocatalysis is beneficial for developing new types of photocatalytic materials with multiple functionalities. In this paper, a comprehensive review of the recent advances toward fabricating and modifying TiO2 mesocrystals is provided, with special focus on the underlying mesocrystallization mechanism and controlling rules. The potential applications of as-synthesized TiO2 mesocrystals in photocatalysis are then discussed to shed light on the structure–performance relationships, thus guiding the development of highly efficient TiO2 mesocrystal-based photocatalysts for certain applications. Finally, the prospects of future research on TiO2 mesocrystals in photocatalysis are briefly highlighted. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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25 pages, 9773 KiB  
Review
Compositing Two-Dimensional Materials with TiO2 for Photocatalysis
by Yu Ren, Yuze Dong, Yaqing Feng and Jialiang Xu
Catalysts 2018, 8(12), 590; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8120590 - 28 Nov 2018
Cited by 31 | Viewed by 8046
Abstract
Energy shortage and environmental pollution problems boost in recent years. Photocatalytic technology is one of the most effective ways to produce clean energy—hydrogen and degrade pollutants under moderate conditions and thus attracts considerable attentions. TiO2 is considered one of the best photocatalysts [...] Read more.
Energy shortage and environmental pollution problems boost in recent years. Photocatalytic technology is one of the most effective ways to produce clean energy—hydrogen and degrade pollutants under moderate conditions and thus attracts considerable attentions. TiO2 is considered one of the best photocatalysts because of its well-behaved photo-corrosion resistance and catalytic activity. However, the traditional TiO2 photocatalyst suffers from limitations of ineffective use of sunlight and rapid carrier recombination rate, which severely suppress its applications in photocatalysis. Surface modification and hybridization of TiO2 has been developed as an effective method to improve its photocatalysis activity. Due to superior physical and chemical properties such as high surface area, suitable bandgap, structural stability and high charge mobility, two-dimensional (2D) material is an ideal modifier composited with TiO2 to achieve enhanced photocatalysis process. In this review, we summarized the preparation methods of 2D material/TiO2 hybrid and drilled down into the role of 2D materials in photocatalysis activities. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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99 pages, 25940 KiB  
Review
Heterogeneous Photocatalysis and Prospects of TiO2-Based Photocatalytic DeNOxing the Atmospheric Environment
by Nick Serpone
Catalysts 2018, 8(11), 553; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8110553 - 16 Nov 2018
Cited by 48 | Viewed by 8288
Abstract
This article reviews the efforts of the last two decades to deNOxify the atmospheric environment with TiO2-based photocatalytic materials supported on various cementitious-like substrates. Prior to undertaking this important aspect of applied photocatalysis with metal-oxide emiconductor photocatalysts, however, it is pertinent [...] Read more.
This article reviews the efforts of the last two decades to deNOxify the atmospheric environment with TiO2-based photocatalytic materials supported on various cementitious-like substrates. Prior to undertaking this important aspect of applied photocatalysis with metal-oxide emiconductor photocatalysts, however, it is pertinent to describe and understand the fundamentals of Heterogeneous Photocatalysis. The many attempts done in a laboratory setting to degrade (deNOxify) the major components that make up the NOx, namely nitric oxide (NO) and nitrogen dioxide (NO2), but most importantly the efforts expended in deNOxifying the real environment upon depositing titania-based coatings on various model and authentic infrastructures, such as urban roads, highway noise barriers, tunnels, and building external walls among others, are examined. Both laboratory and outdoor experimentations have been performed toward NOx being oxidized to form nitrates (NO3−) that remain adsorbed on the TiO2-based photocatalytic surfaces (except in tunnels—indoor walls) but get subsequently dislodged by rain or by periodic washings of the infrastructures. However, no serious considerations have been given to the possible conversion of NOx via photocatalytic reduction back to N2 and O2 gases that would restore the atmospheric environment, as the adsorbed nitrates block the surface-active sites of the photocatalyst and when washed-off ultimately cause unduly damages to the environment. Full article
(This article belongs to the Special Issue Emerging Trends in TiO2 Photocatalysis and Applications)
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