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Special Issue "Nano-Structural Photocatalytic Materials: Synthesis, Characterization and Applications"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Synthesis".

Deadline for manuscript submissions: closed (30 November 2015)

Special Issue Editors

Guest Editor
Prof. Dr. Jimmy C. Yu

Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
Website | E-Mail
Interests: Preparation and characterization of novel nano-structured materials, Environmental applications of photocatalysis, Development of analytical methods for environmental and biological samples
Guest Editor
Dr. Wing-Kei Ho

Department of Science and Environmental Studies, The Hong Kong Institute of Education, Tai Po, New Territories, Hong Kong, China
Website | E-Mail
Interests: Nano-photocatalytic materials with novel morphology, porous structure, and exposed active sites; Identification of catalytic/reaction mechanisms over nanostructured catalysts; Roles of composition, morphology, and structure of nano-photocatalytic materials; Synthesis and characterization of nano-structural photocatalysts; Photocatalytic water splitting; CO2 reduction and removal of environmental pollutants using nano-structural materials; Theoretical calculation, simulation, and modeling of nanomaterials

Special Issue Information

Dear Colleagues,

The rapid development in materials and catalysis science has led to significant advances in understanding the controlled synthesis and structure-activity relationship of nanomaterials. The design, synthesis, and modification of novel nanomaterials allow for enhanced performances in different applications. We cordially invite investigators to contribute original research and review articles that will stimulate further research activities in this area and improve our understanding of the key scientific and technological issues in the applications of photocatalytic nanomaterials. We are particularly interested in articles describing the new strategies for synthesis, assembly, and modification of advanced nanomaterials with novel morphologies, porous structures, and exposed active sites, which greatly benefit their performance, and new insights on the mechanisms of photocatalysis.

Prof. Dr. Jimmy C. Yu
Dr. Wing-Kei Ho
Gest 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 papers will be 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. Molecules 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 1800 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

  • nano-structural photocatalysts
  • photocatalytic reaction mechanism
  • water splitting
  • carbon dioxide reduction
  • environmental purification

Published Papers (10 papers)

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Research

Jump to: Review

Open AccessArticle Constructing a MoS2 QDs/CdS Core/Shell Flowerlike Nanosphere Hierarchical Heterostructure for the Enhanced Stability and Photocatalytic Activity
Molecules 2016, 21(2), 213; doi:10.3390/molecules21020213
Received: 30 November 2015 / Revised: 25 January 2016 / Accepted: 3 February 2016 / Published: 15 February 2016
Cited by 10 | PDF Full-text (2053 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
MoS2 quantum dots (QDs)/CdS core/shell nanospheres with a hierarchical heterostructure have been prepared by a simple microwave hydrothermal method. The as-prepared samples are characterized by XRD, TEM, SEM, UV-VIS diffuse reflectance spectra (DRS) and N2-sorption in detail. The photocatalytic activities
[...] Read more.
MoS2 quantum dots (QDs)/CdS core/shell nanospheres with a hierarchical heterostructure have been prepared by a simple microwave hydrothermal method. The as-prepared samples are characterized by XRD, TEM, SEM, UV-VIS diffuse reflectance spectra (DRS) and N2-sorption in detail. The photocatalytic activities of the samples are evaluated by water splitting into hydrogen. Results show that the as-prepared MoS2 QDs/CdS core/shell nanospheres with a diameter of about 300 nm are composed of the shell of CdS nanorods and the core of MoS2 QDs. For the photocatalytic reaction, the samples exhibit a high stability of the photocatalytic activity and a much higher hydrogen evolution rate than the pure CdS, the composite prepared by a physical mixture, and the Pt-loaded CdS sample. In addition, the stability of CdS has also been greatly enhanced. The effect of the reaction time on the formations of nanospheres, the photoelectric properties and the photocatalytic activities of the samples has been investigated. Finally, a possible photocatalytic reaction process has also been proposed. Full article
Figures

Open AccessArticle Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity
Molecules 2016, 21(2), 181; doi:10.3390/molecules21020181
Received: 5 December 2015 / Revised: 24 January 2016 / Accepted: 28 January 2016 / Published: 1 February 2016
Cited by 4 | PDF Full-text (4271 KB) | HTML Full-text | XML Full-text
Abstract
Semiconductor TiO2 photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH4N2S) modified anatase TiO2 nanorods were fabricated by calcination of the mixture of TiO
[...] Read more.
Semiconductor TiO2 photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH4N2S) modified anatase TiO2 nanorods were fabricated by calcination of the mixture of TiO2 nanorods and thiourea at 600 °C for 2 h. It was found that only N element was doped into the lattice of TiO2 nanorods. With increasing the weight ratio of thiourea to TiO2 (R) from 0 to 8, the light-harvesting ability of the photocatalyst steady increases. Both the crystallization and photocatalytic activity of TiO2 nanorods increase first and then decrease with increase in R value, and R2 sample showed the highest crystallization and photocatalytic activity in degradation of Brilliant Red X3B (X3B) and Rhodamine B (RhB) dyes under visible light irradiation (λ > 420 nm). The increased visible-light photocatalytic activity of the prepared N-doped TiO2 nanorods is due to the synergistic effects of the enhanced crystallization, improved light-harvesting ability and reduced recombination rate of photo-generated electron-hole pairs. Note that the enhanced visible photocatalytic activity of N-doped nanorods is not based on the scarification of their UV photocatalytic activity. Full article
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Open AccessArticle Mechanism of NO Photocatalytic Oxidation on g-C3N4 Was Changed by Pd-QDs Modification
Molecules 2016, 21(1), 36; doi:10.3390/molecules21010036
Received: 1 December 2015 / Revised: 16 December 2015 / Accepted: 17 December 2015 / Published: 26 December 2015
Cited by 11 | PDF Full-text (4485 KB) | HTML Full-text | XML Full-text
Abstract
Quantum dot (QD) sensitization can increase the light absorption and electronic transmission of photocatalysts. However, limited studies have been conducted on the photocatalytic activity of photocatalysts after modification by noble metal QDs. In this study, we developed a simple method for fabricating Pd-QD-modified
[...] Read more.
Quantum dot (QD) sensitization can increase the light absorption and electronic transmission of photocatalysts. However, limited studies have been conducted on the photocatalytic activity of photocatalysts after modification by noble metal QDs. In this study, we developed a simple method for fabricating Pd-QD-modified g-C3N4. Results showed that the modification of Pd-QDs can improve the NO photocatalytic oxidation activity of g-C3N4. Moreover, Pd-QD modification changed the NO oxidation mechanism from the synergistic action of h+ and O2 to the single action of ·OH. We found that the main reason for the mechanism change was that Pd-QD modification changed the molecular oxygen activation pathway from single-electron reduction to two-electron reduction. This study can not only develop a novel strategy for modifying Pd-QDs on the surface of photocatalysts, but also provides insight into the relationship between Pd-QD modification and the NO photocatalytic oxidation activity of semiconductor photocatalysts. Full article
Open AccessArticle Nanocasting of Periodic Mesoporous Materials as an Effective Strategy to Prepare Mixed Phases of Titania
Molecules 2015, 20(12), 21881-21895; doi:10.3390/molecules201219812
Received: 17 November 2015 / Revised: 1 December 2015 / Accepted: 3 December 2015 / Published: 8 December 2015
PDF Full-text (7909 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Mesoporous titanium dioxide materials were prepared using a nanocasting technique involving silica SBA-15 as the hard-template. At an optimal loading of titanium precursor, the hexagonal periodic array of pores in SBA-15 was retained. The phases of titanium dioxide could be easily varied by
[...] Read more.
Mesoporous titanium dioxide materials were prepared using a nanocasting technique involving silica SBA-15 as the hard-template. At an optimal loading of titanium precursor, the hexagonal periodic array of pores in SBA-15 was retained. The phases of titanium dioxide could be easily varied by the number of impregnation cycles and the nature of titanium alkoxide employed. Low number of impregnation cycles produced mixed phases of anatase and TiO2(B). The mesoporous TiO2 materials were tested for solar hydrogen production, and the material consisting of 98% anatase and 2% TiO2(B) exhibited the highest yield of hydrogen from the photocatalytic splitting of water. The periodicity of the pores was an important factor that influenced the photocatalytic activity. This study indicates that mixed phases of titania containing ordered array of pores can be prepared by using the nanocasting strategy. Full article
Open AccessArticle Enhanced Visible Light Photocatalytic Activity of Br-Doped Bismuth Oxide Formate Nanosheets
Molecules 2015, 20(10), 19189-19202; doi:10.3390/molecules201019189
Received: 7 August 2015 / Revised: 3 October 2015 / Accepted: 14 October 2015 / Published: 21 October 2015
Cited by 1 | PDF Full-text (5398 KB) | HTML Full-text | XML Full-text
Abstract
A facile method was developed to enhance the visible light photocatalytic activity of bismuth oxide formate (BiOCOOH) nanosheets via Br-doping. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, the Brunauer–Emmett–Teller surface area, UV-vis diffuse
[...] Read more.
A facile method was developed to enhance the visible light photocatalytic activity of bismuth oxide formate (BiOCOOH) nanosheets via Br-doping. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, the Brunauer–Emmett–Teller surface area, UV-vis diffuse reflectance spectroscopy, photoluminescence spectra, and N2 adsorption-desorption isotherms measurement. The Br ions replaced the COOH ions in the layers of BiOCOOH, result in a decreased layer distance. The photocatalytic activity of the as-prepared materials was evaluated by removal of NO in qir at ppb level. The results showed that the Br-doped BiOCOOH nanosheets showed enhanced visible light photocatalytic activtiy with a NO removal of 37.8%. The enhanced activity can be ascribed to the increased visible light absorption and the promoted charge separation. Full article
Open AccessCommunication Amine-Functionalized ZnO Nanosheets for Efficient CO2 Capture and Photoreduction
Molecules 2015, 20(10), 18847-18855; doi:10.3390/molecules201018847
Received: 20 August 2015 / Revised: 7 October 2015 / Accepted: 14 October 2015 / Published: 16 October 2015
Cited by 8 | PDF Full-text (1773 KB) | HTML Full-text | XML Full-text
Abstract
Amine-functionalized ZnO nanosheets were prepared through a one-step hydrothermal method by using monoethanolamine, which has a hydroxyl group, for covalent attachment on ZnO and a primary amine group to supply the amine-functionalization. We demonstrate that the terminal amine groups on ZnO surfaces substantially
[...] Read more.
Amine-functionalized ZnO nanosheets were prepared through a one-step hydrothermal method by using monoethanolamine, which has a hydroxyl group, for covalent attachment on ZnO and a primary amine group to supply the amine-functionalization. We demonstrate that the terminal amine groups on ZnO surfaces substantially increase the capability of CO2 capture via chemisorption, resulting in effective CO2 activation. As a result, the photogenerated electrons from excited ZnO can more readily reduce the surface-activated CO2, which thereby enhances the activity for photocatalytic CO2 reduction. Full article
Open AccessArticle Cold-Setting Inkjet Printed Titania Patterns Reinforced by Organosilicate Binder
Molecules 2015, 20(9), 16582-16603; doi:10.3390/molecules200916582
Received: 8 June 2015 / Revised: 20 August 2015 / Accepted: 24 August 2015 / Published: 11 September 2015
Cited by 3 | PDF Full-text (1429 KB) | HTML Full-text | XML Full-text
Abstract
A hybrid organo-silica sol was used as a binder for reinforcing of commercial titanium dioxide nanoparticles (Evonic P25) deposited on glass substrates. The organo-silica binder was prepared by the sol-gel process and mixtures of titania nanoparticles with the binder in various ratios were
[...] Read more.
A hybrid organo-silica sol was used as a binder for reinforcing of commercial titanium dioxide nanoparticles (Evonic P25) deposited on glass substrates. The organo-silica binder was prepared by the sol-gel process and mixtures of titania nanoparticles with the binder in various ratios were deposited by materials printing technique. Patterns with both positive and negative features down to 100 µm size and variable thickness were reliably printed by Fujifilm Dimatix inkjet printer. All prepared films well adhered onto substrates, however further post-printing treatment proved to be necessary in order to improve their reactivity. The influence of UV radiation as well as of thermal sintering on the final electrochemical and photocatalytic properties was investigated. A mixture containing 63 wt % of titania delivered a balanced compromise of mechanical stability, generated photocurrent density and photocatalytic activity. Although the heat treated samples yielded generally higher photocurrent, higher photocatalytic activity towards model aqueous pollutant was observed in the case of UV cured samples because of their superhydrophilic properties. While heat sintering remains the superior processing method for inorganic substrates, UV-curing provides a sound treatment option for heat sensitive ones. Full article
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Open AccessArticle Optical Properties of Titania Coatings Prepared by Inkjet Direct Patterning of a Reverse Micelles Sol-Gel Composition
Molecules 2015, 20(8), 14552-14564; doi:10.3390/molecules200814552
Received: 17 June 2015 / Revised: 20 July 2015 / Accepted: 21 July 2015 / Published: 12 August 2015
Cited by 3 | PDF Full-text (3285 KB) | HTML Full-text | XML Full-text
Abstract
Thin layers of titanium dioxide were fabricated by direct inkjet patterning of a reverse micelles sol-gel composition onto soda-lime glass plates. Several series of variable thickness samples were produced by repeated overprinting and these were further calcined at different temperatures. The resulting layers
[...] Read more.
Thin layers of titanium dioxide were fabricated by direct inkjet patterning of a reverse micelles sol-gel composition onto soda-lime glass plates. Several series of variable thickness samples were produced by repeated overprinting and these were further calcined at different temperatures. The resulting layers were inspected by optical and scanning electronic microscopy and their optical properties were investigated by spectroscopic ellipsometry in the range of 200–1000 nm. Thus the influence of the calcination temperature on material as well as optical properties of the patterned micellar titania was studied. The additive nature of the deposition process was demonstrated by a linear dependence of total thickness on the number of printed layers without being significantly affected by the calcination temperature. The micellar imprints structure of the titania layer resulted into significant deviation of measured optical constants from the values reported for bulk titania. The introduction of a void layer into the ellipsometric model was found necessary for this particular type of titania and enabled correct ellipsometric determination of layer thickness, well matching the thickness values from mechanical profilometry. Full article

Review

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Open AccessReview Recent Development of Plasmonic Resonance-Based Photocatalysis and Photovoltaics for Solar Utilization
Molecules 2016, 21(2), 180; doi:10.3390/molecules21020180
Received: 30 November 2015 / Revised: 24 January 2016 / Accepted: 27 January 2016 / Published: 2 February 2016
Cited by 9 | PDF Full-text (4231 KB) | HTML Full-text | XML Full-text
Abstract
Increasing utilization of solar energy is an effective strategy to tackle our energy and energy-related environmental issues. Both solar photocatalysis (PC) and solar photovoltaics (PV) have high potential to develop technologies of many practical applications. Substantial research efforts are devoted to enhancing visible
[...] Read more.
Increasing utilization of solar energy is an effective strategy to tackle our energy and energy-related environmental issues. Both solar photocatalysis (PC) and solar photovoltaics (PV) have high potential to develop technologies of many practical applications. Substantial research efforts are devoted to enhancing visible light activation of the photoelectrocatalytic reactions by various modifications of nanostructured semiconductors. This review paper emphasizes the recent advancement in material modifications by means of the promising localized surface plasmonic resonance (LSPR) mechanisms. The principles of LSPR and its effects on the photonic efficiency of PV and PC are discussed here. Many research findings reveal the promise of Au and Ag plasmonic nanoparticles (NPs). Continual investigation for increasing the stability of the plasmonic NPs will be fruitful. Full article
Open AccessReview Removal of Indoor Volatile Organic Compounds via Photocatalytic Oxidation: A Short Review and Prospect
Molecules 2016, 21(1), 56; doi:10.3390/molecules21010056
Received: 12 November 2015 / Revised: 27 December 2015 / Accepted: 28 December 2015 / Published: 4 January 2016
Cited by 25 | PDF Full-text (438 KB) | HTML Full-text | XML Full-text
Abstract
Volatile organic compounds (VOCs) are ubiquitous in indoor environments. Inhalation of VOCs can cause irritation, difficulty breathing, and nausea, and damage the central nervous system as well as other organs. Formaldehyde is a particularly important VOC as it is even a carcinogen. Removal
[...] Read more.
Volatile organic compounds (VOCs) are ubiquitous in indoor environments. Inhalation of VOCs can cause irritation, difficulty breathing, and nausea, and damage the central nervous system as well as other organs. Formaldehyde is a particularly important VOC as it is even a carcinogen. Removal of VOCs is thus critical to control indoor air quality (IAQ). Photocatalytic oxidation has demonstrated feasibility to remove toxic VOCs and formaldehyde from indoor environments. The technique is highly-chemical stable, inexpensive, non-toxic, and capable of removing a wide variety of organics under light irradiation. In this paper, we review and summarize the traditional air cleaning methods and current photocatalytic oxidation approaches in both of VOCs and formaldehyde degradation in indoor environments. Influencing factors such as temperature, relative humidity, deactivation and reactivations of the photocatalyst are discussed. Aspects of the application of the photocatalytic technique to improve the IAQ are suggested. Full article
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