Research

4554 KiB

Open AccessArticle

UV-Induced Photocatalytic Cashmere Fibers

by Lingyun Wang and Walid A. Daoud

Materials 2017, 10(12), 1414; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10121414 - 11 Dec 2017

Cited by 8 | Viewed by 3196

Cashmere with UV-induced photocatalytic properties is developed for the first time by applying nanocrystalline anatase TiO₂ colloid that is free of inorganic acids and organic solvents via a facile low-temperature one-step sol-gel process. The coated cashmere exhibits remarkable UV-induced photodegradation of methyl [...] Read more.

Cashmere with UV-induced photocatalytic properties is developed for the first time by applying nanocrystalline anatase TiO₂ colloid that is free of inorganic acids and organic solvents via a facile low-temperature one-step sol-gel process. The coated cashmere exhibits remarkable UV-induced photodegradation of methyl orange. Furthermore, the photocatalytic nano-coating on cashmere exhibits significant stability after repetitive washing cycles without the need for chemical or physical pretreatment, where the photocatalytic activities remain almost unchanged after three washing cycles while maintaining a water contact angle above 150°. The one-step functionalization process also minimizes the impact on the peculiar intrinsic properties of cashmere. These findings indicate that cashmere combining reproducible UV-induced photocatalytic activity with stable superhydrophobicity has potential in practical applications. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Figure 1

1424 KiB

Open AccessArticle

Synthesis and Characterization of TiO₂ Nanoparticles for the Reduction of Water Pollutants

by Gigliola Lusvardi, Corrado Barani, Federica Giubertoni and Giulia Paganelli

Materials 2017, 10(10), 1208; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10101208 - 20 Oct 2017

Cited by 72 | Viewed by 5727

Abstract

The aim of this manuscript was the optimization of the synthesis of TiO₂ nanoparticles (TiO₂ NPs) with conditions that could be easily reproducible at the industrial level. Several procedures were tested and those with C₁₂H₂₈O₄Ti [...] Read more.

The aim of this manuscript was the optimization of the synthesis of TiO₂ nanoparticles (TiO₂ NPs) with conditions that could be easily reproducible at the industrial level. Several procedures were tested and those with C₁₂H₂₈O₄Ti and CO(NH₂)₂ as precursors seemed the most promising and, consequently, were improved with different molar ratios, lower temperatures and the addition of NH₄Cl as a secondary dopant of nitrogen. The obtained samples were studied with analytical techniques such as X-ray powder diffraction (XRPD) and field emission scanning electron microscopy (FESEM). To complete the study, dye degradation and bacteriological tests were also performed. The results indicate that it is possible to obtain TiO₂ NPs at lower temperatures with respect to those used in the literature; the best candidate that could satisfy all the requirements was a sample with a molar ratio of C₁₂H₂₈O₄Ti:CO(NH₂)₂ at 2:1 and obtained at 50 °C. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Figure 1

5381 KiB

Open AccessArticle

Preparation and Application of Immobilized Surfactant-Modified PANi-CNT/TiO₂ under Visible-Light Irradiation

by Ching Yuan, Chung-Hsuang Hung, Chung-Shin Yuan and Huei-Wen Li

Materials 2017, 10(8), 877; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10080877 - 29 Jul 2017

Cited by 19 | Viewed by 5303

Abstract

Hydrothermally and sol-gel-synthesized immobilized surfactant-modified polyaniline-carbon nanotubes/TiO₂ (PANi-CNT/TiO₂) photocatalysts were prepared and their application in the degradation of diethyl phthalate (DEP) under visible light at 410 nm was investigated in this sturdy. To improve the dispersion of nanoparticles and the [...] Read more.

Hydrothermally and sol-gel-synthesized immobilized surfactant-modified polyaniline-carbon nanotubes/TiO₂ (PANi-CNT/TiO₂) photocatalysts were prepared and their application in the degradation of diethyl phthalate (DEP) under visible light at 410 nm was investigated in this sturdy. To improve the dispersion of nanoparticles and the transfer of electrons, the TiO₂ surface was modified with both sodium dodecyl sulfate (SDS) and functionalized carbon nanotubes (CNT-COOH and CNT-COCl). With the addition of PANi, which was increased from 1%–5%, the adsorption edge of the prepared photocatalysts shifted to 442 nm. The SDS linked the PANi polymers to achieve a thickness of coating of the film of up to 314–400 nm and 1301–1600 nm for sol-gel hydrolysis and hydrothermally-synthesized photocatalysts, respectively. An appropriate film thickness would extend the transfer path of the electrons and inhibit the recombination of the electrons and the electron-holes. The photo-degradation performance of DEP by the hydrothermally-synthesized photocatalysts was better than those by sol-gel hydrolysis. The results revealed that the hydroxyl radicals were the key oxidant in the degradation of DEP using hydrothermally-synthesized PANi-CNT/TiO₂ photocatalysts. The morphology and functional groups of the raw materials of photocatalysts were characterized and a comparison of photocatalytic activity with other TiO₂-based photocatalysts was also provided. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Graphical abstract

2804 KiB

Open AccessArticle

Structure and Photocatalytic Properties of Mn-Doped TiO₂ Loaded on Wood-Based Activated Carbon Fiber Composites

by Xiaojun Ma, Wanru Zhou and Yin Chen

Materials 2017, 10(6), 631; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10060631 - 09 Jun 2017

Cited by 38 | Viewed by 5550

Abstract

Mn-doped TiO₂ loaded on wood-based activated carbon fiber (Mn/TiO₂-WACF) was prepared by sol–gel and impregnation method using MnSO₄·H₂O as manganese source. The structure of Mn/TiO₂–WACF was characterized by SEM, XRD, FTIR, N₂ adsorption [...] Read more.

Mn-doped TiO₂ loaded on wood-based activated carbon fiber (Mn/TiO₂-WACF) was prepared by sol–gel and impregnation method using MnSO₄·H₂O as manganese source. The structure of Mn/TiO₂–WACF was characterized by SEM, XRD, FTIR, N₂ adsorption and UV–Vis, and its photocatalytic activity for methylene blue degradation was investigated. Results show that Mn-doped TiO₂ were loaded on the surface of wood-based activated carbon fiber with high-development pore structures. The crystallite sizes of Mn-doped TiO₂ in composites were smaller than that of the undoped samples. With an increase of Mn doping content, Ti–O bending vibration intensity of Mn/TiO₂–WACF increased and then decreased. Moreover, Ti–O–Ti and Ti–O–Mn absorption peaks increased upon doping of Mn. Mn/TiO₂–WACF with low specific surface area, and pore volume was improved at 3.5–6.0 nm of mesopore distributions due to the Mn-doped TiO₂ load. In addition, the UV–Vis showed that Mn/TiO₂–WACF (photodegradation rate of 96%) has higher photocatalytic activity than the undoped samples for methylene blue degradation under visible light irradiation. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Figure 1

4034 KiB

Open AccessArticle

Markedly Enhanced Surface Hydroxyl Groups of TiO₂ Nanoparticles with Superior Water-Dispersibility for Photocatalysis

by Chung-Yi Wu, Kuan-Ju Tu, Jin-Pei Deng, Yu-Shiu Lo and Chien-Hou Wu

Materials 2017, 10(5), 566; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10050566 - 22 May 2017

Cited by 144 | Viewed by 13231

Abstract

The benefits of increasing the number of surface hydroxyls on TiO₂ nanoparticles (NPs) are known for environmental and energy applications; however, the roles of the hydroxyl groups have not been characterized and distinguished. Herein, TiO₂ NPs with abundant surface hydroxyl groups [...] Read more.

The benefits of increasing the number of surface hydroxyls on TiO₂ nanoparticles (NPs) are known for environmental and energy applications; however, the roles of the hydroxyl groups have not been characterized and distinguished. Herein, TiO₂ NPs with abundant surface hydroxyl groups were prepared using commercial titanium dioxide (ST-01) powder pretreated with alkaline hydrogen peroxide. Through this simple treatment, the pure anatase phase was retained with an average crystallite size of 5 nm and the surface hydroxyl group density was enhanced to 12.0 OH/nm², estimated by thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Especially, this treatment increased the amounts of terminal hydroxyls five- to six-fold, which could raise the isoelectric point and the positive charges on the TiO₂ surface in water. The photocatalytic efficiency of the obtained TiO₂ NPs was investigated by the photodegradation of sulforhodamine B under visible light irradiation as a function of TiO₂ content, pH of solution, and initial dye concentration. The high surface hydroxyl group density of TiO₂ NPs can not only enhance water-dispersibility but also promote dye sensitization by generating more hydroxyl radicals. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Figure 1

5555 KiB

Open AccessArticle

Immobilization of TiO₂ Nanoparticles on Chlorella pyrenoidosa Cells for Enhanced Visible-Light-Driven Photocatalysis

by Aijun Cai, Aiying Guo and Zichuan Ma

Materials 2017, 10(5), 541; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10050541 - 17 May 2017

Cited by 8 | Viewed by 4712

Abstract

TiO₂ nanoparticles are immobilized on chlorella cells using the hydrothermal method. The morphology, structure, and the visible-light-driven photocatalytic activity of the prepared chlorella/TiO₂ composite are investigated by various methods. The chlorella/TiO₂ composite is found to exhibit larger average sizes and [...] Read more.

TiO₂ nanoparticles are immobilized on chlorella cells using the hydrothermal method. The morphology, structure, and the visible-light-driven photocatalytic activity of the prepared chlorella/TiO₂ composite are investigated by various methods. The chlorella/TiO₂ composite is found to exhibit larger average sizes and higher visible-light intensities. The sensitization of the photosynthesis pigment originating from chlorella cells provides the anatase TiO₂ with higher photocatalytic activities under the visible-light irradiation. The latter is linked to the highly efficient charge separation of the electron/hole pairs. The results also suggest that the photocatalytic activity of the composite remains substantial after four cycles, suggesting a good stability. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Figure 1

7849 KiB

Open AccessArticle

One-Pot Route towards Active TiO₂ Doped Hierarchically Porous Cellulose: Highly Efficient Photocatalysts for Methylene Blue Degradation

by Xiaoxia Sun, Kunpeng Wang, Yu Shu, Fangdong Zou, Boxing Zhang, Guangwu Sun, Hiroshi Uyama and Xinhou Wang

Materials 2017, 10(4), 373; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10040373 - 31 Mar 2017

Cited by 16 | Viewed by 5098

Abstract

In this study, novel photocatalyst monolith materials were successfully fabricated by a non-solvent induced phase separation (NIPS) technique. By adding a certain amount of ethyl acetate (as non-solvent) into a cellulose/LiCl/N,N-dimethylacetamide (DMAc) solution, and successively adding titanium dioxide (TiO [...] Read more.

In this study, novel photocatalyst monolith materials were successfully fabricated by a non-solvent induced phase separation (NIPS) technique. By adding a certain amount of ethyl acetate (as non-solvent) into a cellulose/LiCl/N,N-dimethylacetamide (DMAc) solution, and successively adding titanium dioxide (TiO₂) nanoparticles (NPs), cellulose/TiO₂ composite monoliths with hierarchically porous structures were easily formed. The obtained composite monoliths possessed mesopores, and two kinds of macropores. Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET), and Ultraviolet-visible Spectroscopy (UV-Vis) measurements were adopted to characterize the cellulose/TiO₂ composite monolith. The cellulose/TiO₂ composite monoliths showed high efficiency of photocatalytic activity in the decomposition of methylene blue dye, which was decomposed up to 99% within 60 min under UV light. Moreover, the composite monoliths could retain 90% of the photodegradation efficiency after 10 cycles. The novel NIPS technique has great potential for fabricating recyclable photocatalysts with highly efficiency. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Figure 1

2892 KiB

Open AccessArticle

Photocatalytic Degradation of Organic Dye under UV‐A Irradiation Using TiO2‐Vetiver Multifunctional Nano Particles

by Le Thi Song Thao, Trinh Trung Tri Dang, Wilawan Khanitchaidecha, Duangdao Channei and Auppatham Nakaruk

Materials 2017, 10(2), 122; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10020122 - 30 Jan 2017

Cited by 25 | Viewed by 5132

Abstract

The properties and photocatalytic performance of anatase nanoparticles of pure TiO₂ and a core–shell structure of TiO₂ on calcined vetiver grass leaves have been compared. Samples were fabricated by sol‐gel and heating at 450 °C for 5h.The comparison was based on [...] Read more.

The properties and photocatalytic performance of anatase nanoparticles of pure TiO₂ and a core–shell structure of TiO₂ on calcined vetiver grass leaves have been compared. Samples were fabricated by sol‐gel and heating at 450 °C for 5h.The comparison was based on data for X‐ray diffraction(XRD), UV‐Vis spectrophotometry, photoluminescence, transmission electron microscopy, specific surface area measurement, pore volume assessment, and methylene blue degradation testing. The results showed that the pure TiO2 consisted of agglomerated equiaxed nanoparticles of individual grain sizes in the range 10–20 nm. In contrast, the TiO₂‐vetiver composite exhibited a core–shell structure consisting of a carbonaceous core and TiO₂ shell of thickness 10–15nm. These features influenced the photocatalytic performance in such a way that the lower crosssectional area, greater surface area, and higher pore volume of the TiO₂ shell increased the number of active sites, reduced the charge carrier diffusion distance, and reduced the recombination rate, thereby improving the photocatalytic activity. This improvement derived from morphological characteristics rather than crystallographic, semiconducting, or optical properties. The improved performance of the TiO₂‐vetiver core–shell was unexpected since the X‐ray diffraction data showed that the crystallinity of the TiO₂ was lower than that of the pure TiO₂. These outcomes are attributed to the reducing effect of the carbon on the TiO₂ during heating, thereby facilitating the formation of oxygen vacancies, which enhance charge separation and hence photocatalysis by TiO₂. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Graphical abstract

4099 KiB

Open AccessArticle

Mechanistic Characteristics of Surface Modified Organic Semiconductor g-C₃N₄ Nanotubes Alloyed with Titania

by Lan Ching Sim, Wei Han Tan, Kah Hon Leong, Mohammed J. K. Bashir, Pichiah Saravanan and Nur Atiqah Surib

Materials 2017, 10(1), 28; https://0-doi-org.brum.beds.ac.uk/10.3390/ma10010028 - 03 Jan 2017

Cited by 29 | Viewed by 7313

Abstract

The visible-light-driven photocatalytic degradation of Bisphenol A (BPA) was investigated using the binary composite of alkaline treated g-C₃N₄ (HT-g-C₃N₄) deposited over commercial TiO₂ (Evonik Degussa GmbH, Essen, Germany). The existence and contribution of both TiO [...] Read more.

The visible-light-driven photocatalytic degradation of Bisphenol A (BPA) was investigated using the binary composite of alkaline treated g-C₃N₄ (HT-g-C₃N₄) deposited over commercial TiO₂ (Evonik Degussa GmbH, Essen, Germany). The existence and contribution of both TiO₂ and g-C₃N₄/HT-g-C₃N₄ in the composite was confirmed through various analytical techniques including powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectra (UV-vis-DRS), and photoluminescence (PL) analysis. The results showed that the titania in the binary composite exhibited both pure rutile and anatase phases. The morphological analysis indicated that the spongy “morel-like” structure of g-C₃N₄ turned to nanotube form after alkaline hydrothermal treatment and thereby decreased the specific surface area of HT-g-C₃N₄. The low surface area of HT-g-C₃N₄ dominates its promising optical property and effective charge transfer, resulting in a deprived degradation efficiency of BPA two times lower than pure g-C₃N₄. The binary composite of HT-g-C₃N₄/TiO₂ exhibited excellent degradation efficiency of BPA with 2.16 times higher than the pure HT-g-C₃N₄. The enhanced photocatalytic activity was mainly due to the promising optical band gap structure with heterojunction interface, favorable specific surface area, and good charge separation. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Figure 1

4633 KiB

Open AccessArticle

First Principles Study on the Interaction Mechanisms of Water Molecules on TiO₂ Nanotubes

by Jianhong Dai and Yan Song

Materials 2016, 9(12), 1018; https://0-doi-org.brum.beds.ac.uk/10.3390/ma9121018 - 16 Dec 2016

Cited by 2 | Viewed by 4770

Abstract

The adsorption properties of water molecules on TiO₂ nanotubes (TiO₂NT) and the interaction mechanisms between water molecules are studied by first principles calculations. The adsorption preferences of water molecules in molecular or dissociated states on clean and H-terminated TiO₂ [...] Read more.

The adsorption properties of water molecules on TiO₂ nanotubes (TiO₂NT) and the interaction mechanisms between water molecules are studied by first principles calculations. The adsorption preferences of water molecules in molecular or dissociated states on clean and H-terminated TiO₂NT are evaluated. Adsorption of OH clusters on (0, 6) and (9, 0) TiO₂ nanotubes are first studied. The smallest adsorption energies are −1.163 eV and −1.383 eV, respectively, by examining five different adsorption sites on each type of tube. Eight and six adsorption sites were considered for OH adsorbtion on the H terminated (0, 6) and (9, 0) nanotubes. Water molecules are reformed with the smallest adsorption energy of −4.796 eV on the former and of −5.013 eV on the latter nanotube, respectively. For the adsorption of a single water molecule on TiO₂NT, the molecular state shows the strongest adsorption preference with an adsorption energy of −0.660 eV. The adsorption of multiple (two and three) water molecules on TiO₂NT is also studied. The calculated results show that the interactions between water molecules greatly affect their adsorption properties. Competition occurs between the molecular and dissociated states. The electronic structures are calculated to clarify the interaction mechanisms between water molecules and TiO₂NT. The bonding interactions between H from water and oxygen from TiO₂NT may be the reason for the dissociation of water on TiO₂NT. Full article

(This article belongs to the Special Issue Enhancing the Photocatalytic Activity of TiO2 Photocatalysts)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Enhancing the Photocatalytic Activity of TiO2 Photocatalysts

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (10 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI