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Photocatalytic Nanocomposite Materials
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Photocatalytic Nanocomposite Materials

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

Deadline for manuscript submissions: closed (31 July 2020) | Viewed by 104483

Special Issue Editors

Prof. Dr. Detlef W. Bahnemann

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Guest Editor
Laboratory of Photoactive Nanocomposite Materials, Saint-Petersburg State University, Ulyanovskaya Str. 1, Peterhof, 198504 Saint-Petersburg, Russia
Interests: photocatalysis; self-cleaning; superhydrophilic; antibacterial surfaces; metal and semiconductor particles; nanocristalyne transparent coatings; functional test according to DIN; CEN and ISO
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Alexei Emeline

E-Mail Website
Guest Editor
Saint Petersburg State University, Department of Photonics and Laboratory ”Photoactive Nanocomposite Materials”, Saint-Petersburg State University, St.-Petersburg, Russia
Interests: physics and chemistry of photostimulated interfacial processes in heterogeneous systems, heterogeneous photocatalysis. solar light energy conversion. nanocomposite photoactive materials, experimental and theoretical studies of activity and selectivity of photoactive nanomaterials. self-cleaning photoactive coatings. luminescence materials. photoinduced defect formation in solids, photoelectrochemistry, photovoltaics
Dr. Aida Rudakova

E-Mail Website
Guest Editor
Head of the Division “Synthesis of Photoactive Materials”, Laboratory “Photoactive Nanocomposite Materials”, Saint-Petersburg State University, St Petersburg, Russia
Interests: Catalysis, photocatalysis, design and characterization of photoactive nanocomposite materials, IR and Raman spectroscopy, UV-Vis spectroscopy, luminescence, adsorption, photoinduced hydrophilicity, surface properties, functional coatings
Dr. Kirill M. Bulanin

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Guest Editor
Department of Photonics and Laboratory “Photoactive Nanocomposite Materials”, Saint-Petersburg State University, St.-Petersburg, Russia
Interests: Mechanisms of photoprocesses in heterogeneous systems, Adsorption, photosorption, vibrational spectroscopy, heterogeneous catalysis, intermolecular interactions
Dr. Ruslan Mikhaylov

E-Mail Website
Guest Editor
Saint Petersburg State University, Department of Photonics and Laboratory “Photoactive Nanocomposite Materials”, Saint-Petersburg State University, St.-Petersburg, Russia

Special Issue Information

Dear Colleagues,

This Special Issue of "Photocatalytic Nanocomposite Materials" (PNMs) is devoted to the research into new-generation PNMs, particularly for the processes of solar radiation energy conversion.

Submissions to this Special Issue on “Photocatalytic Nanocomposite Materials” are welcome in the form of original research papers and/or short reviews that reflect the current state of research in the PNM field on the following topics:

  • Design of PNMs;
  • Instrumental methods for investigations of PNMs;
  • Theoretical and experimental studies of the mechanisms of photoprocesses involving PNMs;
  • Photoelectrochemistry of PNMs;
  • Applications of PNMs;
  • Functional coatings based on PNMs;

The focus of this Special Issue will be on the physicochemical principles of creating new materials with purposeful properties for their specific applications. We expect to publish the results of studies that report the true quantities characterizing PNMs instead of “quasi”, “pseudo” and “apparent” characteristics, the true mechanisms strongly supported by experimental and theoretical data instead of believed ones, sophisticated state-of-art experimental methods to explore the new materials, the studies of real photocatalytic processes rather than dye photodegradation, and so on.

The issue will be attractive to researchers whose activities belong to the areas of physical chemistry, materials science, applied and environmental science, focusing on the studies of photocatalytic processes and who are interested in the true development of the science of photocatalysis.

Prof. Dr. Detlef W. Bahnemann
Prof. Dr. Alexei Emeline
Dr. Aida Rudakova
Dr. Kirill M. Bulanin
Dr. Ruslan Mikhaylov
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

  • Photocatalysis
  • Nanostructure
  • Heterojunction
  • Z-scheme
  • Localized surface plasmon resonance
  • Computational studies
  • Reaction mechanism, sustainability
  • Solar energy
  • In situ measurements
  • Photoelectrochemistry
  • Photocatalysts application

Published Papers (26 papers)

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Editorial

Jump to: Research, Review

6 pages, 206 KiB  
Editorial
Editorial: Special Issue on Photocatalytic Nanocomposite Materials (PNMs)
by Detlef W. Bahnemann, Alexei V. Emeline, Aida V. Rudakova, Kirill M. Bulanin and Ruslan V. Mikhaylov
Catalysts 2021, 11(5), 587; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050587 - 30 Apr 2021
Viewed by 1499
Abstract
This Special Issue titled “Photocatalytic Nanocomposite Materials” (PNMs) is devoted to the research into new-generation PNMs, particularly for the processes of solar radiation energy conversion with its focus lying on the physicochemical principles of creating new materials with purposeful properties for their specific [...] Read more.
This Special Issue titled “Photocatalytic Nanocomposite Materials” (PNMs) is devoted to the research into new-generation PNMs, particularly for the processes of solar radiation energy conversion with its focus lying on the physicochemical principles of creating new materials with purposeful properties for their specific applications [...] Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)

Research

Jump to: Editorial, Review

16 pages, 20959 KiB  
Article
Rice Crust-Like ZnO/Ti3C2Tx MXene Hybrid Structures for Improved Photocatalytic Activity
by Qui Thanh Hoai Ta, Nghe My Tran and Jin-Seo Noh
Catalysts 2020, 10(10), 1140; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10101140 - 02 Oct 2020
Cited by 39 | Viewed by 3856
Abstract
Novel two-dimensional ZnO/Ti3C2Tx hybrid photocatalysts with modified surface areas were prepared using a simple calcination technique. The microstructures, crystalline features, and bonding states of the ZnO structure-covered Ti3C2Tx MXenes were closely characterized using [...] Read more.
Novel two-dimensional ZnO/Ti3C2Tx hybrid photocatalysts with modified surface areas were prepared using a simple calcination technique. The microstructures, crystalline features, and bonding states of the ZnO structure-covered Ti3C2Tx MXenes were closely characterized using various tools. The photoluminescence intensity of the hybrid photocatalyst was greatly reduced compared to the pristine ZnO, while its Brunauer-Emmett-Teller (BET) surface area increased by more than 100 times. Under solar light illumination, the photocatalytic degradation efficiency of the hybrid photocatalyst for organic pollutants (MO, RhB) appeared to be three-fold larger as compared to pristine ZnO. The superb photocatalytic performance of the photocatalyst was attributed to several factors, such as ideal band alignment, Schottky barrier formation, and large surface area. Moreover, the ZnO/Ti3C2Tx hybrid photocatalyst showed excellent cycling stability. These results suggest that the novel hybrid structure may be a potential candidate for removing organic pollutants in wastewater. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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14 pages, 4539 KiB  
Article
Dynamics of Photogenerated Charge Carriers in TiO2/MoO3, TiO2/WO3 and TiO2/V2O5 Photocatalysts with Mosaic Structure
by Alexander I. Kokorin, Tatyana V. Sviridova, Elizaveta A. Konstantinova, Dmitry V. Sviridov and Detlef W. Bahnemann
Catalysts 2020, 10(9), 1022; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10091022 - 04 Sep 2020
Cited by 11 | Viewed by 3003
Abstract
Titania is a widely used photocatalytic material possessing such advantages as low cost and high reactivity under the ultraviolet light illumination. However, the fast recombination of photoexcited charge carriers limits its application. Herein, we have synthesized original nanomaterials with mosaic structures that exhibited [...] Read more.
Titania is a widely used photocatalytic material possessing such advantages as low cost and high reactivity under the ultraviolet light illumination. However, the fast recombination of photoexcited charge carriers limits its application. Herein, we have synthesized original nanomaterials with mosaic structures that exhibited well-defined heterojunctions and new properties. Using SEM, XRD, EPR spectroscopy, photocatalytic measurements, and photoinduced pathphysiological activity of these photocatalysts, we studied the processes of charge carrier accumulation in TiO2/MoO3, TiO2/WO3, and TiO2/V2O5 under in situ UV illumination with emphasis on the charge exchange between energy levels of these nanosized semiconductors. It is shown that the accumulation of photoinduced charges occurs in two forms (i) filled electron traps corresponding to Ti4+/Ti3+ levels and (ii) Mo5+ centers, both forms contributing to the photoinduced biocide activity of the samples. This work demonstrates that light exposure of heterostructure photocatalysts with mosaic surfaces produces different types of charge-trapping centers capable of interacting with molecular oxygen yielding peroxo species, which provide long-life light-induced ”self-cleaning” behavior. Such photoaccumulating materials open new opportunities in developing light-driven self-sterilization structures exhibiting a prolonged bactericidal effect up to 10 h after stopping light exposure. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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13 pages, 2760 KiB  
Article
Examination of Photocatalyzed Chlorophenols for Sequential Photocatalytic-Biological Treatment Optimization
by Liliana Bobirică, Constantin Bobirică and Cristina Orbeci
Catalysts 2020, 10(9), 985; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10090985 - 01 Sep 2020
Cited by 4 | Viewed by 2174
Abstract
Given the known adverse effect of chlorophenols for the aquatic environments which they can reach, the development of efficient methods both technically and economically to remove them has gained increasing attention over time. The combination of photocatalytic oxidation with biological treatment can lead [...] Read more.
Given the known adverse effect of chlorophenols for the aquatic environments which they can reach, the development of efficient methods both technically and economically to remove them has gained increasing attention over time. The combination of photocatalytic oxidation with biological treatment can lead to high removal efficiencies of chlorophenols, while reducing the costs associated with the need to treat large volumes of aqueous solutions. Therefore, the present paper had as its main objective the identification of the minimum photocatalytic oxidation period during which the aqueous solutions of 4-chlorophenol and 2,4-dichlorophenol can be considered as readily biodegradable. Thus, the results of photocatalytic oxidation and biodegradability tests showed that, regardless of the concentration of chlorophenol and its type, the working solutions become readily biodegradable after up to 120 min of irradiation in ultraviolet light. At this irradiation time, the maximum organic content of the aqueous solution is less than 40%, and the biochemical oxygen demand and chemical oxygen demand (BOD/COD) ratio is much higher than 0.4. The maximum specific heterotrophic growth rate of activated sludge has an average value of 4.221 d−1 for 4-chlorophenol, and 3.126 d−1 for 2,4-dichlorophenol. This irradiation period represents at most half of the total irradiation period necessary for the complete mineralization of the working solutions. The results obtained were correlated with the intermediates identified during the photocatalytic oxidation. It seems that, working solutions initially containing 4-chlorophenol can more easily form readily biodegradable intermediates. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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12 pages, 3169 KiB  
Article
Noble Metal Modification of CdS-Covered CuInS2 Electrodes for Improved Photoelectrochemical Activity and Stability
by Toshihiro Takashima, Yukitaka Fujishiro and Hiroshi Irie
Catalysts 2020, 10(9), 949; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10090949 - 20 Aug 2020
Cited by 13 | Viewed by 2920
Abstract
In this paper, efficient and stable photoelectrochemical (PEC) hydrogen (H2) evolution using copper indium sulfide (CuInS2) thin film electrodes was studied. Modification with a cadmium sulfide (CdS) layer led to improved charge separation at the interface between CuInS2 [...] Read more.
In this paper, efficient and stable photoelectrochemical (PEC) hydrogen (H2) evolution using copper indium sulfide (CuInS2) thin film electrodes was studied. Modification with a cadmium sulfide (CdS) layer led to improved charge separation at the interface between CuInS2 and CdS; however, the photocorrosive nature of CdS induced poor stability of the photocathode. Further surface coating with an electrodeposited Pt layer over the CdS-covered CuInS2 photocathode prevented the CdS layer from making contact with the electrolyte solution, and enabled efficient PEC H2 evolution without appreciable degradation. This indicates that the Pt layer functioned not only as a reaction site for H2 evolution, but also as a protection layer. In addition, it was found that surface protection using a noble metal layer was also effective for stable PEC carbon dioxide (CO2) reduction when appropriate noble metal cocatalysts were selected. When Au or Ag was used, carbon monoxide was obtained as a product of PEC CO2 reduction. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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14 pages, 4828 KiB  
Article
Curcumin Doped SiO2/TiO2 Nanocomposites for Enhanced Photocatalytic Reduction of Cr (VI) under Visible Light
by Zhiying Yan, Zijuan He, Mi Li, Lin Zhang, Yao Luo, Jiao He, Yongjuan Chen and Jiaqiang Wang
Catalysts 2020, 10(8), 942; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10080942 - 17 Aug 2020
Cited by 14 | Viewed by 2801
Abstract
In order to further improve the photocatalytic performance of the SiO2/TiO2 composite under visible light irradiation, curcumin-doped SiO2/TiO2 nanocomposites were synthesized via directly incorporating it into the structure of SiO2/TiO2 during the synthesis using [...] Read more.
In order to further improve the photocatalytic performance of the SiO2/TiO2 composite under visible light irradiation, curcumin-doped SiO2/TiO2 nanocomposites were synthesized via directly incorporating it into the structure of SiO2/TiO2 during the synthesis using an inexpensive and readily available natural pigment (curcumin) as doping agent. The physicochemical properties of SiO2/TiO2 nanocomposites were characterized in detail by X-ray diffraction, transmission electron microscopy, Fourier transform-infrared spectroscopy, N2 adsorption–desorption isotherms, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. The results indicate that all SiO2/TiO2 nanocomposites exhibited an anatase phase with a typical mesoporous structure. It was found that the dope of curcumin in the SiO2/TiO2 composite could decrease the crystal size, slightly improve the specific surface areas, significantly enhance the visible light absorption, and effectively narrow the band gap energy from 3.04 to 10(eV). Compared with bare SiO2/TiO2, the curcumin-doped SiO2/TiO2 resulted in enhanced photocatalytic reduction activity for Cr(VI) under visible light irradiation, and the CTS (12) sample with the appropriate content of curcumin of 12 wt % shows the photocatalytic yield reaching 100% within 2.5 hours, which is larger than CT (12) without silica. This could be attributed to the curcumin doping and the synergetic effects of SiO2 and TiO2 in SiO2/TiO2 nanocomposites. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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18 pages, 5070 KiB  
Article
Tunable Composition Aqueous-Synthesized Mixed-Phase TiO2 Nanocrystals for Photo-Assisted Water Decontamination: Comparison of Anatase, Brookite and Rutile Photocatalysts
by Konstantina Chalastara, Fuqiang Guo, Samir Elouatik and George P. Demopoulos
Catalysts 2020, 10(4), 407; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10040407 - 08 Apr 2020
Cited by 45 | Viewed by 4290
Abstract
Mixed-phase nanoTiO2 materials attract a lot of attention as advanced photocatalysts for water decontamination due to their intrinsic structure that allows better photo-excited e−cb-h+vb charge separation, hence improved photocatalytic efficiency. Currently, the best-known mixed-phase TiO2 photocatalyst [...] Read more.
Mixed-phase nanoTiO2 materials attract a lot of attention as advanced photocatalysts for water decontamination due to their intrinsic structure that allows better photo-excited e−cb-h+vb charge separation, hence improved photocatalytic efficiency. Currently, the best-known mixed-phase TiO2 photocatalyst is P25 with approximate composition 80% Anatase/20% Rutile (A/r). Apart from Anatase (A) and Rutile (R) phases, there is Brookite (B) which has been evaluated less as photocatalyst in mixed-phase nanoTiO2 systems. In this work we present a sustainable solution process to synthesize tunable composition mixed-phase nanotitania photocatalysts in a continuously stirred tank reactor (CSTR) by modulating conditions like pH, CTiCl4 and time. In particular three mixed-phase TiO2 nanomaterials were produced, namely one predominantly anatase with brookite as minor component (A/b), one predominantly brookite with minor component rutile (B/r), and one predominantly rutile with minor component brookite (R/b) and evaluated as photocatalysts in the degradation of methyl orange. The three semiconducting nanomaterials were characterized by XRD and Raman spectroscopy to quantify the phase ratios and subjected to nano-morphological characterization by FE-SEM and TEM/HR-TEM. The new mixed-phase nanoTiO2 materials are shown to be endowed with large specific surface area, ranging from 90–125 m2 g−1, double of that of P25, to be mesoporous and be surface-rich in Ti–OH molecular groups varying from 12%–20% versus 4% for P25. These properties though impact the adsorptive capacity with R/b and B/r removing > 50% of MO but not photocatalytic activity. The latter depends on nanograined mixed-phase structure and not mere assembly of different phase nanoparticles. First-order rate constants reveal essentially equivalent photocatalytic activity for anatase nanocrystals with either rutile (P25) or brookite (this work) domains. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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16 pages, 3595 KiB  
Article
Enhanced Visible-Light Photocatalysis of Nanocomposites of Copper Oxide and Single-Walled Carbon Nanotubes for the Degradation of Methylene Blue
by Kamal Prasad Sapkota, Insup Lee, Md. Abu Hanif, Md. Akherul Islam, Jeasmin Akter and Jae Ryang Hahn
Catalysts 2020, 10(3), 297; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10030297 - 05 Mar 2020
Cited by 40 | Viewed by 4948
Abstract
We report enhanced catalytic action of a series of copper(II)-oxide-single-walled carbon nanotube (CuO-SWCNT) composite photocatalysts (abbreviated as CuO-SWCNT-0.5, CuO-SWCNT-2, and CuO-SWCNT-5, where 0.5, 2, and 5 represent the calcination time in hours) synthesized via recrystallization followed by calcination. The photocatalytic performance of the [...] Read more.
We report enhanced catalytic action of a series of copper(II)-oxide-single-walled carbon nanotube (CuO-SWCNT) composite photocatalysts (abbreviated as CuO-SWCNT-0.5, CuO-SWCNT-2, and CuO-SWCNT-5, where 0.5, 2, and 5 represent the calcination time in hours) synthesized via recrystallization followed by calcination. The photocatalytic performance of the fabricated nanocomposites was examined by evaluating the degradation of methylene blue (MB) under irradiation with visible light. All of the as-fabricated nanocomposites were effective photocatalysts for the photodegradation of a MB solution; however, the CuO-SWCNT-5 displayed the best photocatalytic ability among the investigated catalysts, achieving 97.33% degradation of MB in 2 h under visible-light irradiation. The photocatalytic action of the nanocomposites was remarkably higher than that of pristine CuO nanocrystals fabricated using the same route. The recyclability of the photocatalyst was also investigated; the CuO-SWCNT-5 catalyst could be reused for three cycles without substantial degradation of its catalytic performance or morphology. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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14 pages, 3511 KiB  
Article
The Effect of Carbon Content on Methanol Oxidation and Photo-Oxidation at Pt-TiO2-C Electrodes
by Athanasios Papaderakis, Olga Spyridou, Nikolaos Karanasios, Aikaterini Touni, Angeliki Banti, Nina Dimitrova, Stephan Armyanov, Eugenia Valova, Jenia Georgieva and Sotiris Sotiropoulos
Catalysts 2020, 10(2), 248; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10020248 - 19 Feb 2020
Cited by 13 | Viewed by 3566
Abstract
The oxidation of methanol is studied at TiO2-supported Pt electrodes of varied high surface area carbon content (in the 30-5% w/w range) and C÷Ti atom ratio (in the 3.0-0.4 ratio). The Pt-TiO2 catalyst is prepared by a photo-deposition process and [...] Read more.
The oxidation of methanol is studied at TiO2-supported Pt electrodes of varied high surface area carbon content (in the 30-5% w/w range) and C÷Ti atom ratio (in the 3.0-0.4 ratio). The Pt-TiO2 catalyst is prepared by a photo-deposition process and C nanoparticles (Vulcan XC72R) are added by simple ultrasonic mixing. The optimum C÷Ti atom ratio of the prepared catalyst for methanol electro-oxidation is found to be 1.5, resulting from the interplay of C properties (increased electronic conductivity and methanol adsorption), those of TiO2 (synergistic effect on Pt and photo-activity), as well as the catalyst film thickness. The intrinsic catalytic activity of the best Pt-TiO2/C catalyst is better than that of a commercial Pt/C catalyst and could be further improved by nearly 25% upon UV illumination, whose periodic application can also limit current deterioration. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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15 pages, 4063 KiB  
Article
Preparation of Quasi-MIL-101(Cr) Loaded Ceria Catalysts for the Selective Catalytic Reduction of NOx at Low Temperature
by Min Lu, Haili Hou, Chuanying Wei, Xiaohui Guan, Wei Wei and Guang-Sheng Wang
Catalysts 2020, 10(1), 140; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10010140 - 20 Jan 2020
Cited by 19 | Viewed by 3172
Abstract
At present, the development of novel catalysts with high activity Selective Catalytic Reduction (SCR) reaction at the low temperature is still a challenge. In this work, the authors prepare CeO2/quasi-MIL-101 catalysts with various amounts of deposited ceria by a double-solvent method, [...] Read more.
At present, the development of novel catalysts with high activity Selective Catalytic Reduction (SCR) reaction at the low temperature is still a challenge. In this work, the authors prepare CeO2/quasi-MIL-101 catalysts with various amounts of deposited ceria by a double-solvent method, which are characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and so on. The results show that the increase of Ce content has a great influence on the catalytic property of the catalyst. The introduction of Ce can promote the conversion between Cr3+ and Cr5+ and increase the proportion of lattice oxygen, which improves the activity of the catalyst. However, the catalyst will be peroxidized when the content of Ce is too high, resulting in the decline of the catalytic activity. This experiment indicates that CeO2/quasi-MIL-101 plays a significant role in the NH3-SCR process at the low temperature when the loading of Ce is 0.5%. This work has proved the potential of this kind of material in NH3-SCR process at the low temperature, providing help for subsequent studies. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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12 pages, 3041 KiB  
Article
Structural Evolution of Ni-Based Co-Catalysts on [Ca2Nb3O10]− Nanosheets during Heating and Their Photocatalytic Properties
by Siyuan Zhang, Leo Diehl, Sina Wrede, Bettina V. Lotsch and Christina Scheu
Catalysts 2020, 10(1), 13; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10010013 - 20 Dec 2019
Cited by 6 | Viewed by 3934
Abstract
Nickel compounds are among the most frequently used co-catalysts for photocatalytic water splitting. By loading Ni(II) precursors, submonolayer Ni(OH)2 was uniformly distributed onto photocatalytic [Ca2Nb3O10]− nanosheets. Further heating of the nanocomposite was studied both ex [...] Read more.
Nickel compounds are among the most frequently used co-catalysts for photocatalytic water splitting. By loading Ni(II) precursors, submonolayer Ni(OH)2 was uniformly distributed onto photocatalytic [Ca2Nb3O10]− nanosheets. Further heating of the nanocomposite was studied both ex situ in various gas environments and in situ under vacuum in the scanning transmission electron microscope. During heating in non-oxidative environments including H2, argon and vacuum, Ni nanoparticles form at ≥200 °C, and they undergo Ostwald ripening at ≥500 °C. High resolution imaging and electron energy loss spectroscopy revealed a NiO shell around the Ni core. Ni loading of up to 3 wt% was demonstrated to enhance the rates of photocatalytic hydrogen evolution. After heat treatment, a further increase in the reaction rate can be achieved thanks to the Ni core/NiO shell nanoparticles and their large separation. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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14 pages, 2776 KiB  
Article
Photoelectrochemical Behavior of the Ternary Heterostructured Systems CdS/WO3/TiO2
by Anna A. Murashkina, Tair V. Bakiev, Yurii M. Artemev, Aida V. Rudakova, Alexei V. Emeline and Detlef W. Bahnemann
Catalysts 2019, 9(12), 999; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9120999 - 27 Nov 2019
Cited by 10 | Viewed by 3616
Abstract
In this article, we report the results of comparative studies of photoelectrochemical behavior of the binary CdS/TiO2 and WO3/TiO2 and ternary CdS/WO3/TiO2 heterostructures based on titania nanotube and planar structures. Physical–chemical characterization by XRD, XPS, and [...] Read more.
In this article, we report the results of comparative studies of photoelectrochemical behavior of the binary CdS/TiO2 and WO3/TiO2 and ternary CdS/WO3/TiO2 heterostructures based on titania nanotube and planar structures. Physical–chemical characterization by XRD, XPS, and electron microscopy methods together with electrochemical impedance spectroscopy measurements confirm a successful formation of heterostructured electrodes, both nanotube-based and planar. The results of photoelectrochemical studies of the heterostructures demonstrate a significant difference in their behavior depending on the structure geometry and the character of the formed heterojunctions. It is concluded that nanotube-based heterostructure electrodes can be characterized by a stochastic set of different heterojunctions while planar systems demonstrate well-ordered heterojunctions with a strictly defined electron transfer direction. Particularly, we demonstrate the possibility of the realization of Z-scheme of photoexcitation and charge separation in ternary planar systems under visible light irradiation. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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13 pages, 3231 KiB  
Article
Hydrogen Production from Aqueous Methanol Solutions Using Ti–Zr Mixed Oxides as Photocatalysts under UV Irradiation
by Alejandro Pérez-Larios, Jose L. Rico, Luis M. Anaya-Esparza, O.A. González Vargas, Napoleón González-Silva and Ricardo Gómez
Catalysts 2019, 9(11), 938; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9110938 - 08 Nov 2019
Cited by 12 | Viewed by 2481
Abstract
The synthesis and characterisation of Ti–Zr mixed oxides containing 1 to 10 wt.% of Zr is herein reported. In addition, the samples were tested as photocatalysts in the generation of hydrogen from aqueous methanol solutions. The solids were prepared by sol-gel and then [...] Read more.
The synthesis and characterisation of Ti–Zr mixed oxides containing 1 to 10 wt.% of Zr is herein reported. In addition, the samples were tested as photocatalysts in the generation of hydrogen from aqueous methanol solutions. The solids were prepared by sol-gel and then characterised by X-ray diffraction, high resolution electron microscopy, X-ray photoelectron spectroscopy, physisorption of nitrogen, scanning electron microscopy, UV-vis and Raman spectroscopies. The results show the presence of anatase as a predominant structure and the oxides present larger specific surface areas than that of pure titania. A maximum value of 168 m2/g was determined for the sample with 5 wt.% of zirconium. The calculated band gap energies varied from 3.05 to 3.15 eV. It was observed that the greater the zirconium content in the solid, the higher the generation rate of hydrogen when testing the Ti–Zr solids as photocatalysts. Under our experimental conditions, the best catalyst, Ti–Zr oxide with 10 wt.% Zr, showed a production rate of 2100 μmol of H2/h which was about tenfold higher than that observed for pure titania. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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15 pages, 5931 KiB  
Article
Cooperative Catalytic Behavior of SnO2 and NiWO4 over BiVO4 Photoanodes for Enhanced Photoelectrochemical Water Splitting Performance
by Maged N. Shaddad, Prabhakarn Arunachalam, Mahmoud Hezam and Abdullah M. Al-Mayouf
Catalysts 2019, 9(11), 879; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9110879 - 23 Oct 2019
Cited by 13 | Viewed by 3736
Abstract
n-BiVO4 is a favorable photoelectrode candidate for a photoelectrochemical (PEC) water splitting reaction owing to its suitable energy level edge locations for an oxygen evolution reaction. On the other hand, the sluggish water oxidation kinetics of BiVO4 photoanodes when used individually [...] Read more.
n-BiVO4 is a favorable photoelectrode candidate for a photoelectrochemical (PEC) water splitting reaction owing to its suitable energy level edge locations for an oxygen evolution reaction. On the other hand, the sluggish water oxidation kinetics of BiVO4 photoanodes when used individually make it necessary to use a hole blocking layer as well as water oxidation catalysts to overcome the high kinetic barrier for the PEC water oxidation reaction. Here, we describe a very simple synthetic strategy to fabricate nanocomposite photoanodes that synergistically address both of these critical limitations. In particular, we examine the effect of a SnO2 buffer layer over BiVO4 films and further modify the photoanode surface with a crystalline nickel tungstate (NiWO4) nanoparticle film to boost PEC water oxidation. When NiWO4 is incorporated over BiVO4/SnO2 films, the PEC performance of the resultant triple-layer NiWO4/BiVO4/SnO2 films for the oxygen evolution reaction (OER) is further improved. The enhanced performance for the PEC OER is credited to the synergetic effect of the individual layers and the introduction of a SnO2 buffer layer over the BiVO4 film. The optimized NiWO4/BiVO4/SnO2 electrode demonstrated both enriched visible light absorption and achieves charge separation and transfer efficiencies of 23% and 30%, respectively. The photoanodic current density for the OER on optimized NiWO4/BiVO4/SnO2 photoanode shows a maximum photocurrent of 0.93 mA/cm2 at 1.23 V vs. RHE in a phosphate buffer solution (pH~7.5) under an AM1.5G solar simulator, which is an incredible five-fold and two-fold enhancement compared to its parent BiVO4 photoanode and BiVO4/SnO2 photoanodes, respectively. Further, the incorporation of the NiWO4 co-catalyst over the BiVO4/SnO2 film increases the interfacial electron transfer rate across the composite/solution interface. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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13 pages, 1084 KiB  
Article
Immobilized rGO/TiO2 Photocatalyst for Decontamination of Water
by Radek Zouzelka, Monika Remzova, Jan Plsek, Libor Brabec and Jiri Rathousky
Catalysts 2019, 9(9), 708; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9090708 - 23 Aug 2019
Cited by 25 | Viewed by 4003
Abstract
The preparation of immobilized graphene-based photocatalyst layers is highly desired for environmental applications. In this study, the preparation of an immobilized reduced graphene oxide (rGO)/TiO2 composite by electrophoretic deposition (EPD) was optimized. It enabled quantitative deposition without sintering and without the use [...] Read more.
The preparation of immobilized graphene-based photocatalyst layers is highly desired for environmental applications. In this study, the preparation of an immobilized reduced graphene oxide (rGO)/TiO2 composite by electrophoretic deposition (EPD) was optimized. It enabled quantitative deposition without sintering and without the use of any dispersive additive. The presence of rGO had beneficial effects on the photocatalytic degradation of 4-chlorophenol in an aqueous solution. A marked increase in the photocatalytic degradation rate was observed, even at very low concentrations of rGO. Compared with the TiO2 and GO/TiO2 reference layers, use of the rGO/TiO2 composite (0.5 wt% of rGO) increased the first-order reaction rate constant by about 70%. This enhanced performance was due to the increased formation of hydroxyl radicals that attacked the 4-chlorophenol molecules. The direct charge transfer mechanism had only limited effect on the degradation. Thus, EPD-prepared rGO/TiO2 layers appear to be suitable for environmental application. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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9 pages, 1111 KiB  
Article
Photodegradation of Herbicide Imazapyr and Phenol over Mesoporous Bicrystalline Phases TiO2: A Kinetic Study
by Mohamed Faycal Atitar, Adel. A. Ismail, Ralf Dillert and Detlef W. Bahnemann
Catalysts 2019, 9(8), 640; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9080640 - 27 Jul 2019
Cited by 13 | Viewed by 2548
Abstract
Mesoporous TiO2 nanoparticles were synthesized at different temperatures (400–800 °C). The resulting mesoporous anatase–rutile TiO2 mixtures between 27 and 82% were found to have different structural properties (morphology, mesoporosity, crystallite phases, and sizes) affected through the calcination process. They were tested [...] Read more.
Mesoporous TiO2 nanoparticles were synthesized at different temperatures (400–800 °C). The resulting mesoporous anatase–rutile TiO2 mixtures between 27 and 82% were found to have different structural properties (morphology, mesoporosity, crystallite phases, and sizes) affected through the calcination process. They were tested for the photocatalytic degradation of the herbicides imazapyr and phenol, compared with the nonporous TiO2 P-25. The present work is an extension of a previously published study discussing the influence of the rutile content on the photocatalytic performance of the nanocrystals, based on the modified first order kinetic model, where the degradation rate is a function of the specific surface area of the material. The apparent degradation rate using T-800 is 10-fold higher than in the case using TiO2 P-25. The material with the lowest anatase content (T-800) exhibits the highest photocatalytic activity in terms of initial reaction rate per unit surface area. It is considered that mixed-phase photocatalysts with rutile–anatase exhibit enhanced photoactivity with the increase of the rutile proportion. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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14 pages, 4656 KiB  
Article
Facile Synthesis of Heterojunctioned ZnO/Bi2S3 Nanocomposites for Enhanced Photocatalytic Reduction of Aqueous Cr(VI) under Visible-Light Irradiation
by Xiaoya Yuan, Xue Wu, Zijuan Feng, Wen Jia, Xuxu Zheng and Chuanqiang Li
Catalysts 2019, 9(7), 624; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9070624 - 21 Jul 2019
Cited by 32 | Viewed by 4314
Abstract
Heterojunctioned ZnO/Bi2S3 nanocomposites were prepared via a facile solvothermal method. The obtained photocatalysts were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and [...] Read more.
Heterojunctioned ZnO/Bi2S3 nanocomposites were prepared via a facile solvothermal method. The obtained photocatalysts were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and Photoelectrochemical and Photoluminescence spectroscopy (PL), respectively. The results showed that ZnO/Bi2S3 composites exhibited the sandwiched-like structure, where ZnO nanoparticles were randomly embedded between Bi2S3 nanoflakes. The performance of photocatalytic Cr(VI) reduction under visible light indicated that ZnO/Bi2S3 composites exhibited high-efficiency photocatalytic activity in comparison with either Bi2S3 or ZnO. The 5%-ZnO/Bi2S3 photocatalyst removed 96% of Cr(VI) within 120 min at 20 mg/L initial concentration of Cr(VI). The enhanced performance of ZnO/Bi2S3 photocatalysts could be ascribed to the increased light harvesting and the effective separation and transfer of the photogenerated charge carriers across the heterojunction interface of the ZnO/Bi2S3 composite. This work could pave the way for the design of new hetero-structured materials and has great potential in environmental remediation. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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14 pages, 5623 KiB  
Article
AgBr/(Sr0.6Bi0.305)2Bi2O7 Heterostructured Composites: Fabrication, Characterization, and Significantly Enhanced Photocatalytic Activity
by Xinling Wang, Di Zhu, Yan Zhong, Dianhui Wang and Chaohao Hu
Catalysts 2019, 9(5), 394; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9050394 - 26 Apr 2019
Cited by 6 | Viewed by 3007
Abstract
The pyrochlore-type (Sr0.6Bi0.305)2Bi2O7 (SBO) containing Bi3+ and Bi5+ mixed valent states was first investigated as a photocatalyst in our very recent work. To further improve the photocatalytic performance, AgBr/SBO heterostructured composites were [...] Read more.
The pyrochlore-type (Sr0.6Bi0.305)2Bi2O7 (SBO) containing Bi3+ and Bi5+ mixed valent states was first investigated as a photocatalyst in our very recent work. To further improve the photocatalytic performance, AgBr/SBO heterostructured composites were synthesized by using a deposition-precipitation method. The characterization of phase structure, morphology, microstructure, elemental composition, and optical properties of the obtained products were performed using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM)TEM, X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic activity of samples was evaluated by degrading methylene blue under visible light illumination. AgBr/SBO composites possess high stability and significantly enhanced photocatalytic performance. The improvement of photocatalytic activity is due to the enhanced light absorption and the separation of photoinduced electrons and holes on the interface of AgBr/SBO heterostructured composites. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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12 pages, 6624 KiB  
Article
MoS2/CdS Heterostructure for Enhanced Photoelectrochemical Performance under Visible Light
by Guannan He, Yimin Zhang and Qinyu He
Catalysts 2019, 9(4), 379; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9040379 - 23 Apr 2019
Cited by 35 | Viewed by 5330
Abstract
High-rate recombination of photogenerated electron and hole pairs will lead to low photocatalytic activity. Constructing heterostructure is a way to address this problem and thus increase the photoelectrochemical performance of the photocatalysts. In this article, molybdenum sulfide (MoS2)/cadmium sulfide (CdS) nanocomposites [...] Read more.
High-rate recombination of photogenerated electron and hole pairs will lead to low photocatalytic activity. Constructing heterostructure is a way to address this problem and thus increase the photoelectrochemical performance of the photocatalysts. In this article, molybdenum sulfide (MoS2)/cadmium sulfide (CdS) nanocomposites were fabricated by a facile solvothermal method after sonication. The CdS nanoparticles immobilized on the MoS2 sheet retained the original crystal structure and morphology. The composites exhibit higher photoelectrochemical properties compared with pure MoS2 nanosheets or CdS powder. When the precursor concentration of CdS is 0.015 M, the MoS2/CdS composites yield the highest photocurrent, which is enhanced nearly five times compared with pure CdS or MoS2. The improved photoelectrochemical performance can be ascribed to the increase of light harvest, as well as to the heterostructure that decreases the recombination rate of the photogenerated electron and hole pairs. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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16 pages, 3294 KiB  
Article
Characterization and Effect of Ag(0) vs. Ag(I) Species and Their Localized Plasmon Resonance on Photochemically Inactive TiO2
by Chanel Tri Handoko, Nikolaos G. Moustakas, Tim Peppel, Armin Springer, Freddy E. Oropeza, Adri Huda, Muhammad Djoni Bustan, Bambang Yudono, Fakhili Gulo and Jennifer Strunk
Catalysts 2019, 9(4), 323; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9040323 - 02 Apr 2019
Cited by 20 | Viewed by 3740
Abstract
Commercial TiO2 (anatase) was successfully modified with Ag nanoparticles at different nominal loadings (1%–4%) using a liquid impregnation method. The prepared materials retained the anatase structure and contained a mixture of Ag0 and AgI species. Samples exhibited extended light absorption [...] Read more.
Commercial TiO2 (anatase) was successfully modified with Ag nanoparticles at different nominal loadings (1%–4%) using a liquid impregnation method. The prepared materials retained the anatase structure and contained a mixture of Ag0 and AgI species. Samples exhibited extended light absorption to the visible region. The effect of Ag loading on TiO2 is studied for the photocatalytic reduction of CO2 to CH4 in a gas–solid process under high-purity conditions. It is remarkable that the reference TiO2 used in this work is entirely inactive in this reaction, but it allows for studying the effect of Ag on the photocatalytic process in more detail. Only in the case of 2% Ag/TiO2 was the formation of CH4 from CO2 observed. Using different light sources, an influence of the localized surface plasmon resonance (LSPR) effect of Ag is verified. A sample in which all Ag has been reduced to the metallic state was less active than the respective sample containing both Ag0 and Ag+, indicating that a mixed oxidation state is beneficial for photocatalytic performance. These results contribute to a better understanding of the effect of metal modification of TiO2 in photocatalytic CO2 reduction. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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12 pages, 4964 KiB  
Article
Enhanced Visible Light Photocatalytic Reduction of Cr(VI) over a Novel Square Nanotube Poly(Triazine Imide)/TiO2 Heterojunction
by Xin Yan, Guotao Ning and Peng Zhao
Catalysts 2019, 9(1), 55; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9010055 - 08 Jan 2019
Cited by 15 | Viewed by 3970
Abstract
Hexavalent chromium Cr(VI) pollution makes has a harmful impact on human health and the ecological environment. Photocatalysis reduction technology exhibits low energy consumption, high reduction efficiency and stable performance, and is playing an increasingly important role in chromium pollution control. Graphite-phase carbon nitride [...] Read more.
Hexavalent chromium Cr(VI) pollution makes has a harmful impact on human health and the ecological environment. Photocatalysis reduction technology exhibits low energy consumption, high reduction efficiency and stable performance, and is playing an increasingly important role in chromium pollution control. Graphite-phase carbon nitride has been used to reduce Cr(VI) to the less harmful Cr(III) due to its visible light catalytic activity, chemical stability and low cost. However, it has a low specific surface area and fast recombination of electron–hole pairs, which severely restrict its practical application. In this work, a TiO2-modified poly(triazine imide) (PTI) square nanotube was prepared by the one-step molten salts method. The results showed the PTI had a square hollow nanotube morphology, with an about 100–1000 nm width and 60–70 nm thickness. During the formation of the PTI square tube, TiO2 nanoparticles adhere to the surface of the square tube wall by strong adsorption, and eventually form a PTI/TiO2 heterojunction. The PTI/TiO2-7 wt% heterojunction exhibited very good Cr(VI) reduction efficiency within 120 min. The enhanced photocatalytic activity was mainly attributed to the efficient separation and transport of photo-induced electron–hole pairs and the high specific surface area in the heterojunction structure. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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9 pages, 2889 KiB  
Article
Network Structured CuWO4/BiVO4/Co-Pi Nanocomposite for Solar Water Splitting
by Ben Peng, Mengyang Xia, Chao Li, Changshen Yue and Peng Diao
Catalysts 2018, 8(12), 663; https://0-doi-org.brum.beds.ac.uk/10.3390/catal8120663 - 17 Dec 2018
Cited by 16 | Viewed by 5579
Abstract
A network structured CuWO4/BiVO4 nanocomposite with a high specific surface area was prepared from CuWO4 nanoflake (NF) arrays via a method that combined drop-casting and thermal annealing. The obtained CuWO4/BiVO4 exhibited high catalytic activity toward photoelectrochemical [...] Read more.
A network structured CuWO4/BiVO4 nanocomposite with a high specific surface area was prepared from CuWO4 nanoflake (NF) arrays via a method that combined drop-casting and thermal annealing. The obtained CuWO4/BiVO4 exhibited high catalytic activity toward photoelectrochemical (PEC) water oxidation. When cobalt phosphate (Co-Pi) was coupled with CuWO4/BiVO4, the activity of the resulting CuWO4/BiVO4/Co-Pi composite for the oxygen evolution reaction (OER) was further improved. The photocurrent density (Jph) for OER on CuWO4/BiVO4/Co-Pi is among the highest reported on a CuWO4-based photoanode in a neutral solution. The high activity for the PEC OER was attributed to the high specific surface area of the composite, the formation of a CuWO4/BiVO4 heterojunction that accelerated electron–hole separation, and the coupling of the Co-Pi co-catalyst with CuWO4/BiVO4, which improved the charge transfer rate across composite/solution interface. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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Review

Jump to: Editorial, Research

31 pages, 5784 KiB  
Review
Photoactive Heterostructures: How They Are Made and Explored
by Alexei V. Emeline, Aida V. Rudakova, Ruslan V. Mikhaylov, Kirill M. Bulanin and Detlef W. Bahnemann
Catalysts 2021, 11(2), 294; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11020294 - 23 Feb 2021
Cited by 13 | Viewed by 3259
Abstract
In our review we consider the results on the development and exploration of heterostructured photoactive materials with major attention focused on what are the better ways to form this type of materials and how to explore them correctly. Regardless of what type of [...] Read more.
In our review we consider the results on the development and exploration of heterostructured photoactive materials with major attention focused on what are the better ways to form this type of materials and how to explore them correctly. Regardless of what type of heterostructure, metal–semiconductor or semiconductor–semiconductor, is formed, its functionality strongly depends on the quality of heterojunction. In turn, it depends on the selection of the heterostructure components (their chemical and physical properties) and on the proper choice of the synthesis method. Several examples of the different approaches such as in situ and ex situ, bottom-up and top-down, are reviewed. At the same time, even if the synthesis of heterostructured photoactive materials seems to be successful, strong experimental physical evidence demonstrating true heterojunction formation are required. A possibility for obtaining such evidence using different physical techniques is discussed. Particularly, it is demonstrated that the ability of optical spectroscopy to study heterostructured materials is in fact very limited. At the same time, such experimental techniques as high-resolution transmission electron microscopy (HRTEM) and electrophysical methods (work function measurements and impedance spectroscopy) present a true signature of heterojunction formation. Therefore, whatever the purpose of heterostructure formation and studies is, the application of HRTEM and electrophysical methods is necessary to confirm that formation of the heterojunction was successful. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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20 pages, 4788 KiB  
Review
Photocatalytic Nanocomposite Materials Based on Inorganic Polymers (Geopolymers): A Review
by Mahroo Falah and Kenneth J. D. MacKenzie
Catalysts 2020, 10(10), 1158; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10101158 - 09 Oct 2020
Cited by 19 | Viewed by 3554
Abstract
Geopolymers are ecologically-friendly inorganic materials which can be produced at low temperatures from industrial wastes such as fly ash, blast furnace slags or mining residues. Although to date their principal applications have been seen as alternatives to Portland cement building materials, their properties [...] Read more.
Geopolymers are ecologically-friendly inorganic materials which can be produced at low temperatures from industrial wastes such as fly ash, blast furnace slags or mining residues. Although to date their principal applications have been seen as alternatives to Portland cement building materials, their properties make them suitable for a number of more advanced applications, including as photocatalytic nanocomposites for removal of hazardous pollutants from waste water or the atmosphere. For this purpose, they can be combined with photocatalytic moieties such as metal oxides with suitable bandgaps to couple with UV or visible radiation, or with carbon nanotubes or graphene. In these composites the geopolymers act as supports for the photoactive components, but geopolymers formed from wastes containing oxides such as Fe2O3 show intrinsic photoactive behaviour. This review discusses the structure and formation chemistry of geopolymers and the principles required for their utilisation as photocatalysts. The literature on existing photocatalytic geopolymers is reviewed, suggesting that these materials have a promising potential as inexpensive, efficient and ecologically-friendly candidates for the remediation of toxic environmental pollutants and would repay further development. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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31 pages, 6027 KiB  
Review
Recent Advances in Niobium-Based Materials for Photocatalytic Solar Fuel Production
by Barbara Nascimento Nunes, Osmando Ferreira Lopes, Antonio Otavio T. Patrocinio and Detlef W. Bahnemann
Catalysts 2020, 10(1), 126; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10010126 - 16 Jan 2020
Cited by 59 | Viewed by 7333
Abstract
The search for renewable and clean energy sources is a key aspect for sustainable development as energy consumption has continuously increased over the years concomitantly with environmental concerns caused by the use of fossil fuels. Semiconductor materials have great potential for acting as [...] Read more.
The search for renewable and clean energy sources is a key aspect for sustainable development as energy consumption has continuously increased over the years concomitantly with environmental concerns caused by the use of fossil fuels. Semiconductor materials have great potential for acting as photocatalysts for solar fuel production, a potential energy source able to solve both energy and environmental concerns. Among the studied semiconductor materials, those based on niobium pentacation are still shallowly explored, although the number of publications and patents on Nb(V)-based photocatalysts has increased in the last years. A large variety of Nb(V)-based materials exhibit suitable electronic/morphological properties for light-driving reactions. Not only the extensive group of Nb2O5 polymorphs is explored, but also many types of layered niobates, mixed oxides, and Nb(V)-doped semiconductors. Therefore, the aim of this manuscript is to provide a review of the latest developments of niobium based photocatalysts for energy conversion into fuels, more specifically, CO2 reduction to hydrocarbons or H2 evolution from water. Additionally, the main strategies for improving the photocatalytic performance of niobium-based materials are discussed. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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28 pages, 3572 KiB  
Review
Polymer Nanocomposites for Photocatalytic Applications
by Violeta Melinte, Lenuta Stroea and Andreea L. Chibac-Scutaru
Catalysts 2019, 9(12), 986; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9120986 - 24 Nov 2019
Cited by 79 | Viewed by 10366
Abstract
In the present comprehensive review we have specifically focused on polymer nanocomposites used as photocatalytic materials in fine organic reactions or in organic pollutants degradation. The selection of the polymer substrates for the immobilization of the active catalyst particles is motivated by several [...] Read more.
In the present comprehensive review we have specifically focused on polymer nanocomposites used as photocatalytic materials in fine organic reactions or in organic pollutants degradation. The selection of the polymer substrates for the immobilization of the active catalyst particles is motivated by several advantages displayed by them, such as: Environmental stability, chemical inertness and resistance to ultraviolet radiations, mechanical stability, low prices and ease availability. Additionally, the use of polymer nanocomposites as photocatalysts offers the possibility of a facile separation and reuse of the materials, eliminating thus the post-treatment separation processes and implicitly reducing the costs of the procedure. This review covers the polymer-based photocatalytic materials containing the most popular inorganic nanoparticles with good catalytic performance under UV or visible light, namely TiO2, ZnO, CeO2, or plasmonic (Ag, Au, Pt, Pd) NPs. The study is mainly targeted on the preparation, photocatalytic activity, strategies directed toward the increase of photocatalytic efficiency under visible light and reuse of the hybrid polymer catalysts. Full article
(This article belongs to the Special Issue Photocatalytic Nanocomposite Materials)
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