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Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis...
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Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II

A special issue of Photochem (ISSN 2673-7256).

Deadline for manuscript submissions: closed (30 December 2022) | Viewed by 16653

Special Issue Editor

Dr. Vincenzo Vaiano

E-Mail Website
Guest Editor
Department of Industrial Engineering, University Salerno, Via Giovanni Paolo 2 132, I-84084 Fisciano, Salerno, Italy
Interests: photocatalysis for sustainable chemistry; photocatalytic and photo-fenton processes for pollutants removal in wastewater; catalytic combustion of sewage sludge; decomposition and oxidative decomposition of H2S; hydrolysis of COS in the liquid phase
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In view of the success of the first edition of the Special Issue, I would like to open the possibility to additional researchers to contribute to the second edition of the Special Issue entitled “Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II”.

As in the first edition, research and review papers related to novel photocatalytic materials and their use in the visible (or solar light) driven photocatalytic removal of pollutants from liquid and gaseous phases are welcome in this Special Issue. Moreover, innovative photocatalyst formulations studied in chemical reactions devoted to the selective synthesis of organic compounds (e.g., phenol from benzene, aniline from nitrobenzene, methanol from methane, organic compounds from CO2) will be considered.

Dr. Vincenzo Vaiano
Guest Editor

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. Photochem is an international peer-reviewed open access quarterly 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 1000 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
  • doped and co-doped semiconductors
  • heterojunctions
  • metal–organic framework (MOFs)
  • water and wastewater treatment
  • gaseous pollutant removal
  • organic synthesis
  • CO2 photoconversion

Published Papers (8 papers)

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Research

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10 pages, 6814 KiB  
Article
Facile Synthesis, Characterization, and Photocatalytic Performance of BiOF/BiFeO3 Hybrid Heterojunction for Benzylamine Coupling under Simulated Light Irradiation
by Abdalla S. Abdelhamid, Reem H. Alzard, Lamia A. Siddig, Aya Elbahnasy, Duha Aljazmati, Zaina Kadoura, Hind Zeidane, Rufaida Elshikh and Ahmed Alzamly
Photochem 2023, 3(1), 187-196; https://doi.org/10.3390/photochem3010012 - 21 Mar 2023
Viewed by 1623
Abstract
Under simulated light irradiation, the aerobic oxidation of benzylamine to N,N-benzylidenebenzylamine was carried out as a model reaction to investigate the photocatalytic activity of a hydrothermally prepared composite based on BiOF and BiFeO3 materials. The prepared photocatalysts were characterized [...] Read more.
Under simulated light irradiation, the aerobic oxidation of benzylamine to N,N-benzylidenebenzylamine was carried out as a model reaction to investigate the photocatalytic activity of a hydrothermally prepared composite based on BiOF and BiFeO3 materials. The prepared photocatalysts were characterized using several spectroscopic techniques, such as powder X-ray diffraction (PXRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). Band gap analysis showed that the composite exhibits a band gap that lies in the UV region (3.5 eV). Nonetheless, pristine BiOF and BiFeO3 exhibited band gaps of 3.8 eV and 2.15 eV, respectively. N,N-benzylidenebenzylamine was selectively achieved with a high conversion yield of ~80% under atmospheric conditions in which the product was confirmed using 1H-NMR, 13C-NMR, and FTIR spectroscopic techniques. Various control experiments were conducted to further confirm the enhanced photocatalytic performance of the reported composite. Full article
(This article belongs to the Special Issue Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II)
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13 pages, 2562 KiB  
Article
Application of Zirconia/Alumina Composite Oxide Ceramics as Photocatalysts for Removal of 2,4,6-Trichlorophenol from Water
by Tatjana D. Vulić, Milica V. Carević, Nadica D. Abazović, Tatjana B. Novaković, Zorica D. Mojović and Mirjana I. Čomor
Photochem 2022, 2(4), 905-917; https://doi.org/10.3390/photochem2040058 - 28 Nov 2022
Cited by 3 | Viewed by 1493
Abstract
The mesoporous zirconia/alumina composites were synthesized via a sol–gel method, followed by heat treatment at 500 °C for 5 h. The effect of the ZrO2/Al2O3 ratio on the structural and textural properties of the obtained composites was explored. [...] Read more.
The mesoporous zirconia/alumina composites were synthesized via a sol–gel method, followed by heat treatment at 500 °C for 5 h. The effect of the ZrO2/Al2O3 ratio on the structural and textural properties of the obtained composites was explored. Sorption analysis has confirmed that all samples have a mesoporous structure whose parameters (SBET, Vp and Dmax) strongly depend on the ZrO2/Al2O3 ratio. The XRD pattern of composites has shown that the addition of zirconia disrupts the crystallinity of alumina. The composites with higher zirconia content (50% ZrO2 and 67% ZrO2) are characterized by peaks related only to the zirconia phase. UV/Vis diffuse reflection spectra of all samples revealed that composites have more intensive absorption compared to pure oxides for wavelengths larger than 250 nm and similar band gaps. Photoluminescence measurements showed presence of defects in all samples, which are responsible for photocatalytic activity. All samples showed significant adsorption/photocatalytic efficacy for the removal/degradation of 2,4,6 -trichlorophenol (TCP). Results obtained using HPLC and TOC techniques showed that between 70 and 80% of the initial TCP concentration was removed/degraded after 4 h of illumination. These results were corelated with flat, conduction and valence band potentials of synthesized pure and binary oxides, calculated using Mott–Schottky plots. Full article
(This article belongs to the Special Issue Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II)
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14 pages, 3136 KiB  
Article
Increasing the Photocatalytic Activity of BiVO4 by Naked Co(OH)2 Nanoparticle Cocatalysts
by Luiz E. Gomes, Luiz F. Plaça, Washington S. Rosa, Renato V. Gonçalves, Sajjad Ullah and Heberton Wender
Photochem 2022, 2(4), 866-879; https://doi.org/10.3390/photochem2040055 - 12 Oct 2022
Cited by 2 | Viewed by 1834
Abstract
Bismuth vanadate (BiVO4 or BVO) is one of the most studied photocatalysts for water oxidation because of its excellent visible light absorption and appropriate band energy positions. However, BVO presents a low charge mobility and a high electron–hole recombination rate. To address [...] Read more.
Bismuth vanadate (BiVO4 or BVO) is one of the most studied photocatalysts for water oxidation because of its excellent visible light absorption and appropriate band energy positions. However, BVO presents a low charge mobility and a high electron–hole recombination rate. To address these fundamental limitations, this study proposes the coating of previously synthesized phase-pure monoclinic scheelite BVO with different amounts of naked cobalt (further oxidized to cobalt hydroxide) nanoparticles (NPs) via a modified magnetron sputtering deposition. The resulting BVO/Co photocatalysts were investigated for methylene blue (MB) photodegradation, photocatalytic oxygen evolution, and photoelectrochemical (PEC) water oxidation. In the MB photodegradation tests, the BVO/Co sample prepared with a deposition time of 5 min (BVO/Co(5 min)) presented the highest photoactivity (k = 0.06 min−1) compared with the other sputtering investigated times (k = 0.01–0.02 min−1), as well as the pristine BVO sample (k = 0.04 min−1). A similar trend was evidenced for the PEC water oxidation, where a photocurrent density of 23 µA.cm−2 at 1.23 V (vs. RHE) was observed for the BVO/Co(5 min) sample, a value 4.6 times higher compared with pristine BVO. Finally, the BVO/Co(5 min) presented an O2 evolution more than two times higher than that of the pristine BVO. The increased photocatalytic performance was ascribed to increased visible-light absorption, lesser electron–hole recombination, and enhanced charge transfer at the liquid/solid interface. The deposition of Co(OH)2 NPs via magnetron sputtering can be considered an effective strategy to improve the photocatalytic performance of BVO for different target catalytic reactions, including oxygen evolution, water oxidation, and pollutant photodegradation. Full article
(This article belongs to the Special Issue Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II)
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19 pages, 3118 KiB  
Article
Low-Cost and Recyclable Photocatalysts: Metal Oxide/Polymer Composites Applied in the Catalytic Breakdown of Dyes
by Timur Borjigin, Michael Schmitt, Fabrice Morlet-Savary, Pu Xiao and Jacques Lalevée
Photochem 2022, 2(3), 733-751; https://doi.org/10.3390/photochem2030047 - 24 Aug 2022
Cited by 8 | Viewed by 2054
Abstract
Novel metal oxide/polymer composite photocatalysts prepared by photocuring with common metal oxide particles (ZnO or CeO2) and acrylic ester monomers have been investigated for the first time. Metal oxide particles were fully integrated with the acrylate polymer network based on the [...] Read more.
Novel metal oxide/polymer composite photocatalysts prepared by photocuring with common metal oxide particles (ZnO or CeO2) and acrylic ester monomers have been investigated for the first time. Metal oxide particles were fully integrated with the acrylate polymer network based on the crosslink of poly ethylene glycol diacrylate (noted below as Poly-PEG) by photopolymerization upon mild light source (LED@405 nm) irradiation. The prepared metal/oxide composite showed excellent performance in the photodegradation of Acid Black dye (used as a benchmark pollutant) in an aqueous environment. Indeed, under UV lamp irradiation for 60 min, the degradation of Acid Black reached 59% and 56%, in the presence of 10 wt% ZnO/Poly-PEG and 3 wt% CeO2/poly PEG, respectively. Markedly, the new reported photocatalysts have offered much better performance over the conventional TiO2 photocatalytic material used as a control (39% degradation using 1 wt% TiO2/poly PEG). In turn, the new proposed metal oxide/polymer composites were further characterized by a range of analytical characterization methods, including the swelling test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), dynamic mechanical analysis (DMA), UV–visible diffuse reflectance spectroscopy, and electron spin resonance analysis. The results showed that the new photocatalysts demonstrated excellent water adsorption properties, high-temperature resistance, and excellent recyclability, which were very suitable for wide application and in line with the concept of green chemistry. Full article
(This article belongs to the Special Issue Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II)
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13 pages, 1924 KiB  
Article
Optical and Structural Characteristics of Rare Earth-Doped ZnO Nanocrystals Prepared in Colloidal Solution
by Maria Toma, Oleksandr Selyshchev, Yevhenii Havryliuk, Aurel Pop and Dietrich R. T. Zahn
Photochem 2022, 2(3), 515-527; https://doi.org/10.3390/photochem2030036 - 02 Jul 2022
Cited by 9 | Viewed by 2087
Abstract
ZnO nanocrystals doped with Nd, Gd, and Er were synthesized using a soft chemical process in ambient atmosphere. Pseudospherical and hexagonal nanocrystals (NC) of the wurtzite phase with a mean size of (7.4 ± 1.7) nm were obtained. The presence of rare earth [...] Read more.
ZnO nanocrystals doped with Nd, Gd, and Er were synthesized using a soft chemical process in ambient atmosphere. Pseudospherical and hexagonal nanocrystals (NC) of the wurtzite phase with a mean size of (7.4 ± 1.7) nm were obtained. The presence of rare earth (RE) dopants was confirmed by X-ray fluorescence (XRF) spectroscopy. The ZnO nanocrystals exhibited simultaneously narrow excitonic- and broad trap/surface-related photoluminescence (PL), both of which were affected by doping with RE atoms. Doping reduced the total PL intensity, suppressing the excitonic emission by a greater extent than the broad band PL. Also, doping resulted in a blue shift of the trap/surface-related emission, while the energy of the excitonic peak remained unchanged. Resonant Raman spectra additionally confirmed the wurtzite phase of ZnO NCs and revealed a shift of the A1-LO mode towards lower frequency upon doping that could be caused by the mass effect of RE atoms, point defects, and increases in charge carrier concentration. Fitting of the spectra with Voigt profiles showed better results with two surface optical (SO) phonon modes that were previously theoretically predicted for the wurtzite ZnO phase. The influence of RE doping on PL and Raman spectra can be explained by the incorporation of RE ions into the ZnO nanostructures, where the dopants act as non-radiative defects. Full article
(This article belongs to the Special Issue Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II)
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Review

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21 pages, 6632 KiB  
Review
Mechanistic Insights into Graphene Oxide Driven Photocatalysis as Co-Catalyst and Sole Catalyst in Degradation of Organic Dye Pollutants
by Jai Prakash
Photochem 2022, 2(3), 651-671; https://doi.org/10.3390/photochem2030043 - 17 Aug 2022
Cited by 13 | Viewed by 2512
Abstract
Photocatalysis is a promising route to utilize sunlight, which has been potentially used to solve energy as well as environmental problems with an emphasis on fundamental understanding and technological applications in society. Semiconductors are excellent photocatalysts but often show less efficient activities due [...] Read more.
Photocatalysis is a promising route to utilize sunlight, which has been potentially used to solve energy as well as environmental problems with an emphasis on fundamental understanding and technological applications in society. Semiconductors are excellent photocatalysts but often show less efficient activities due to the fast recombination of photogenerated charge carriers and very slow kinetics of surface photochemical reactions. However, recent advancements show promising strategies to improve their photocatalytic activities, including surface modifications using suitable co-catalysts and the development of novel efficient photocatalysts. Graphene oxide (GO) is one of such nanomaterials which shows multifarious roles in photocatalysis with a great potential to act as an independent solar-driven sole photocatalyst. In this minireview, the photochemistry of GO has been discussed in view of its multifarious roles/mechanisms in improving the photocatalytic activity of metal oxide semiconductors, plasmonic nanomaterials, and also their nanocomposites. In addition, recent advancements and applications of such GO-based photocatalysts in photocatalytic degradation of organic dye pollutants, including engineering of GO as the sole photocatalyst, have been discussed. Furthermore, the challenges and future prospects for the development of GO-based photocatalysts are discussed. Full article
(This article belongs to the Special Issue Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II)
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19 pages, 1874 KiB  
Review
Solid State Nanostructured Metal Oxides as Photocatalysts and Their Application in Pollutant Degradation: A Review
by Carlos Díaz, Marjorie Segovia and Maria Luisa Valenzuela
Photochem 2022, 2(3), 609-627; https://doi.org/10.3390/photochem2030041 - 05 Aug 2022
Cited by 9 | Viewed by 2213
Abstract
Most dyes used in various industries are toxic and carcinogenic, thus posing a serious hazard to humans as well as to the marine ecosystem. Therefore, the impact of dyes released into the environment has been studied extensively in the last few years. Heterogeneous [...] Read more.
Most dyes used in various industries are toxic and carcinogenic, thus posing a serious hazard to humans as well as to the marine ecosystem. Therefore, the impact of dyes released into the environment has been studied extensively in the last few years. Heterogeneous photocatalysis has proved to be an efficient tool for degrading both atmospheric and aquatic organic contaminants. It uses the sunlight in the presence of a semiconductor photocatalyst to accelerate the remediation of environmental contaminants and the destruction of highly toxic molecules. To date, photocatalysis has been considered one of the most appealing options for wastewater treatment due to its great potential and high efficiency by using sunlight to remove organic pollutants and harmful bacteria with the aid of a solid photocatalyst. Among the photocatalysts currently used, nanostructured metal oxide semiconductors have been among the most effective. This review paper presents an overview of the recent research improvements on the degradation of dyes by using nanostructured metal oxide semiconductors obtained by a solid-state method. Metal oxides obtained by this method exhibited better photocatalytic efficiency than nanostructured metal oxides obtained using other solution methods in several cases. The present review discusses examples of various nanostructured transition metal oxides—such as TiO2, Fe2O3, NiO, ReO3, IrO2, Rh2O3, Rh/RhO2, and the actinide ThO2—used as photocatalysts on methylene blue. It was found that photocatalytic efficiency depends not only on the bandgap of the metal oxide but also on its morphology. Porous nanostructured metal oxides tend to present higher photocatalytic efficiency than metal oxides with a similar band gap. Full article
(This article belongs to the Special Issue Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II)
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29 pages, 3176 KiB  
Review
Progress in the Photoreforming of Carboxylic Acids for Hydrogen Production
by Anita Samage, Pooja Gupta, Mahaveer A. Halakarni, Sanna Kotrappanavar Nataraj and Apurba Sinhamahapatra
Photochem 2022, 2(3), 580-608; https://doi.org/10.3390/photochem2030040 - 29 Jul 2022
Cited by 4 | Viewed by 2050
Abstract
Photoreforming is a process that connects the redox capability of photocatalysts upon light illumination to simultaneously drive the reduction of protons into hydrogen and the oxidation of organic substrates. Over the past few decades, researchers have devoted substantial efforts to enhancing the photocatalytic [...] Read more.
Photoreforming is a process that connects the redox capability of photocatalysts upon light illumination to simultaneously drive the reduction of protons into hydrogen and the oxidation of organic substrates. Over the past few decades, researchers have devoted substantial efforts to enhancing the photocatalytic activity of the catalyst in hydrogen production. Currently, the realization of the potential of photocatalysts for simultaneous hydrogen production with value-added organics has motivated the research field to use the photo-oxidation path. As a distinct benefit, the less energetically demanding organic reforming is highly favorable compared to the slow kinetics of oxygen evolution, negating the need for expensive and/or harmful hole scavengers. Photocatalyst modifications, such as secondary component deposition, doping, defect, phase and morphology engineering, have been the main strategies adopted to tune the photo-oxidation pathways and oxidation products. The effect of the reaction parameters, including temperature, pH, reactant concentration and promising reactor strategies, can further enhance selectivity toward desired outcomes. This review provides a critical overview of photocatalysts in hydrogen production, including chemical reactions occurring with semiconductors and co-catalysts. The use of various oxygenates as sacrificial agents for hydrogen production is outlined in view of the transition of fossil fuels to clean energy. This review mainly focuses on recent development in the photoreforming of carboxylic acids, produced from the primary source, lignocellulose, through pyrolysis. The photo-oxidation of different carboxylic acids, e.g., formic acid, acetic acid and lactic acid, over different photocatalysts for hydrogen production is reviewed. Full article
(This article belongs to the Special Issue Visible Light Active Photocatalysts for Environmental Remediation and Organic Synthesis II)
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