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Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts

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

Deadline for manuscript submissions: closed (31 July 2019) | Viewed by 35014

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Special Issue Editors

Prof. Dr. Juan Matos Lale

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Guest Editor

Institute of Applied Chemical Science, Faculty of Engineering, "Autonomous University of Chile", Santiago 8900000, Región Metropolitana, Chile
Interests: photocatalysis; carbon materials; hybrid materials; solar irradiation; solar/chemical fuels

Dr. Alicia Gomis Berenguer

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Guest Editor

CEMHTI Site Haute Température, CNRS (UPR 3079), 1D Av. de la Recherche Scientifique CS 90055, 45071 Orléans, CEDEX 2, France
Interests: photochemistry; photoelectrochemistry; nanoporous carbons; adsorption; carbon/ligth interactions; energy conversion; advanced oxidation processes

Special Issue Information

Dear Colleagues,

One of the main challenges of a global energy strategy is the development of new sustainable fuels and chemicals based on renewable energies. Solar fuels and chemicals are promising strategic pathways since they are produced from simple and abundant molecules using a renewable energy source such as sunlight. However, although the scientific and technological achievements reached to date have been many, the efficiency is still low and far for the practical application. Thus, highly active photocatalysts are required to produce solar and chemical fuels.

The purpose of this Special Issue, entitled “Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts” is to cover significant recent advances in the area of solar chemicals, also referred to as solar-driven chemical reactions, using advanced oxidation/reduction processes through the development of efficient semiconductor/carbon-based photocatalysts. Works related with the eco-friendly synthesis routes of innovative carbon-based photocatalysts for the production of energy vectors like H₂or other fuels, CO₂reduction, photo-assisted valorization of organic molecules, and the environmental remediation of polluted water and air are welcome to be submitted to this Special Issue.

Prof. Dr. Juan Matos Lale
Dr. Alicia Gomis Berenguer
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. Molecules is an international peer-reviewed open access semimonthly 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

Photochemistry
Energy conversion
Semiconductor/Carbon material
Solar chemicals

Published Papers (7 papers)

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Research

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20 pages, 3010 KiB

Open AccessFeature PaperArticle

Hybrid Material Based on an Amorphous-Carbon Matrix and ZnO/Zn for the Solar Photocatalytic Degradation of Basic Blue 41

by Silvania Lanfredi, Marcos A. L. Nobre, Po S. Poon and Juan Matos

Molecules 2020, 25(1), 96; https://doi.org/10.3390/molecules25010096 - 26 Dec 2019

Cited by 14 | Viewed by 3875

Abstract

Innovative composites based on an amorphous-carbon matrix containing a second phase ZnO oxide and/or highly dispersed Zn metallic were synthesized via a modified Pechini route, in which a partial pyrolysis method was reached. Studies of adsorption in the dark and the photocatalytic activity for the cationic azo-dye, basic blue 41, and degradation were carried out. X-ray diffraction patterns for the carbon matrix and its composite with Zn show characteristics of the amorphous carbon. The infrared in the mid region of the composite prepared with ZnO and Zn exhibit vibrational bands related to bonds zinc oxide. The surface pH of the material is the main factor responsible for the adsorption of the azo-dye, but the contribution of mesopores favored the diffusion of molecules from the bulk of solution to the pore framework. Esters-like functional groups on the surface of carbons hinder the adsorption of the azo-dye. When Zn is embedded within amorphous carbon the photocatalytic activity of the composites showed up to 2.4 higher than neat ZnO. The enhancement in the photocatalytic activity and stability of C/ZnO/Zn and C/Zn composites is discussed in terms of a protector effect by the carbon layers inserted in composites. Carbon layers are responsible to inhibit the lixiviation of ZnO particles along irradiation. Full article

(This article belongs to the Special Issue Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts)

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13 pages, 3721 KiB

Open AccessArticle

TiO₂/S-Doped Carbons Hybrids: Analysis of Their Interfacial and Surface Features

by Teresa J. Bandosz, Alfonso Policicchio, Marc Florent, Po S. Poon and Juan Matos

Molecules 2019, 24(19), 3585; https://doi.org/10.3390/molecules24193585 - 05 Oct 2019

Cited by 8 | Viewed by 2341

Abstract

Hybrids containing approximately equal amounts of P25 TiO₂ and S-doped porous carbons were prepared using a water-based slurry mixing method. The materials were extensively characterized by adsorption of nitrogen, potentiometric titration, thermal analysis in air and in helium, XRD, XPS and SEM. The collected results showed the significant blockage of carbon micropores by TiO₂ particles deposited on their outer surface. The formation of a new interface, especially for the S-rich samples, might also contribute to the porosity alteration. Analysis of surface chemistry suggested the presence of Ti-S bonds with an involvement of sulfur from thiophenic species in the carbon phase. The latter, especially when polymer-derived, was mainly deposited on the TiO₂ nanoparticles. Formation of Ti-S stabilized sulfur and increased the ignition temperature of the hybrids, especially those with a high content of sulfur, in comparison with the ignition temperature of carbons. The surfaces of hybrid with S-containing carbons was also thermally very stable and of basic chemical nature. The formation of interfacial structures Ti-C was detected by XPS analysis suggesting a partial reduction of the Ti. Full article

(This article belongs to the Special Issue Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts)

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14 pages, 2213 KiB

Open AccessArticle

Bacterial Inactivation on Concrete Plates Loaded with Modified TiO₂ Photocatalysts under Visible Light Irradiation

by Magdalena Janus, Ewelina Kusiak-Nejman, Paulina Rokicka-Konieczna, Agata Markowska-Szczupak, Kamila Zając and Antoni W. Morawski

Molecules 2019, 24(17), 3026; https://doi.org/10.3390/molecules24173026 - 21 Aug 2019

Cited by 23 | Viewed by 2896

Abstract

The antibacterial activity of concrete plates loaded with various titania photocatalysts was investigated. The target in bacteria testing was Escherichia coli K12. The presence of photocatalysts in the concrete matrix at a dose of 10 wt.% improved the antibacterial properties, which became significant depending on the type of the added photocatalyst. Total inactivation of E. coli irradiated under artificial solar light was observed on the concrete plates loaded with the following photocatalysts: TiO₂/N,C_MeOH-300, TiO₂/N,C_EtOH-100, TiO₂/N,C_isoPrOH-100 and TiO₂/N-300. The modified Hom disinfection kinetic model was found as a best-fit model for the obtained results. The presence of nitrogen and carbon in the photocatalysts structure, as well as crystallite size, surface area and porosity, contributed to the increase of antibacterial properties of concrete plates. Full article

(This article belongs to the Special Issue Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts)

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11 pages, 1622 KiB

Open AccessArticle

Optimization of Cyclohexanol and Cyclohexanone Yield in the Photocatalytic Oxofunctionalization of Cyclohexane over Degussa P-25 under Visible Light

by Adolfo Henríquez, Victoria Melin, Nataly Moreno, Héctor D. Mansilla and David Contreras

Molecules 2019, 24(12), 2244; https://doi.org/10.3390/molecules24122244 - 15 Jun 2019

Cited by 6 | Viewed by 3776

Abstract

The sustainable transformation of basic chemicals into organic compounds of industrial interest using mild oxidation processes has proved to be challenging. The production of cyclohexanol and cyclohexanone from cyclohexane is of interest to the nylon manufacturing industry. However, the industrial oxidation of cyclohexane is inefficient. Heterogeneous photocatalysis represents an alternative way to synthesize these products, but the optimization of this process is difficult. In this work, the yields of photocatalytic cyclohexane conversion using Degussa P-25 under visible light were optimized. To improve cyclohexanol production, acetonitrile was used as an inert photocatalytic solvent. Experiments showed that the use of the optimized conditions under solar light radiation did not affect the cyclohexanol/cyclohexanone ratio. In addition, the main radical intermediary produced in the reaction was detected by the electronic paramagnetic resonance technique. Full article

(This article belongs to the Special Issue Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts)

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14 pages, 1890 KiB

Open AccessArticle

Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater

by Juan Jose Viña Mediavilla, Begoña Fernandez Perez, Maria C. Fernandez de Cordoba, Julia Ayala Espina and Conchi O. Ania

Molecules 2019, 24(7), 1373; https://doi.org/10.3390/molecules24071373 - 08 Apr 2019

Cited by 23 | Viewed by 3742

Abstract

We have explored the simultaneous degradation of cyanides and thiocyanate present in wastewaters from a cokemaking factory using photoassisted methods under varied illumination conditions (from simulated solar light to UV light). Overall, the photochemical degradation of cyanides was more efficient than that of thiocyanates, regardless of the illumination conditions, the effect being more pronounced in the absence of a photocatalyst. This is due to their different degradation mechanism that in the case of thiocyanates is dominated by fast recombination reactions and/or charge transfer reactions to electron scavengers. In all cases, cyanate, ammonia, nitrates, and nitrites were formed at different amounts depending on the illumination conditions. The conversion yield under simulated solar light was almost complete for cyanides and quite high for thiocyanates after 6 h of illumination. Regarding toxicity, photochemical oxidation at 254 nm and under simulated solar light decreased significantly the toxicity of the pristine wastewater, showing a correlation with the intensity of the irradiation source. This indicate that simulated light can be effectively used to reduce the toxicity of industrial effluents, opening an interesting perspective for optimizing cyanide detoxification systems based on natural light. Full article

(This article belongs to the Special Issue Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts)

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Review

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40 pages, 3823 KiB

Open AccessReview

Photocatalytic Degradation of Pharmaceuticals Carbamazepine, Diclofenac, and Sulfamethoxazole by Semiconductor and Carbon Materials: A Review

by Ana S. Mestre and Ana P. Carvalho

Molecules 2019, 24(20), 3702; https://doi.org/10.3390/molecules24203702 - 15 Oct 2019

Cited by 90 | Viewed by 9985

Abstract

The presence of pharmaceutical compounds in the environment is a reality that calls for more efficient water treatment technologies. Photocatalysis is a powerful technology available but the high energy costs associated with the use of UV irradiation hinder its large scale implementation. More sustainable and cheaper photocatalytic processes can be achieved by improving the sunlight harvesting and the synthesis of semiconductor/carbon composites has proved to be a promising strategy. Carbamazepine, diclofenac, and sulfamethoxazole were selected as target pharmaceuticals due to their recalcitrant behavior during conventional wastewater treatment and persistence in the environment, as properly reviewed. The literature data on the photocatalytic removal of carbamazepine, diclofenac, and sulfamethoxazole by semiconductor/carbon materials was critically revised to highlight the role of the carbon in the enhanced semiconductor performance under solar irradiation. Generally it was demonstrated that carbon materials induce red-shift absorption and they contribute to more effective charge separation, thus improving the composite photoactivity. Carbon was added as a dopant (C-doping) or as support or doping materials (i.e., nanoporous carbons, carbon nanotubes (CNTs), graphene, and derived materials, carbon quantum dots (CQDs), and biochars) and in the large majority of the cases, TiO₂ was the semiconductor tested. The specific role of carbon materials is dependent on their properties but even the more amorphous forms, like nanoporous carbons or biochars, allow to prepare composites with improved properties compared to the bare semiconductor. The self-photocatalytic activity of the carbon materials was also reported and should be further explored. The removal and mineralization rates, as well as degradation pathways and toxicity of the treated solutions were also critically analyzed. Full article

(This article belongs to the Special Issue Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts)

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21 pages, 4923 KiB

Open AccessReview

Graphene-Based Materials as Efficient Photocatalysts for Water Splitting

by Josep Albero, Diego Mateo and Hermenegildo García

Molecules 2019, 24(5), 906; https://doi.org/10.3390/molecules24050906 - 05 Mar 2019

Cited by 78 | Viewed by 7362

Abstract

Photocatalysis has been proposed as one of the most promising approaches for solar fuel production. Among the photocatalysts studied for water splitting, graphene and related materials have recently emerged as attractive candidates due to their striking properties and sustainable production when obtained from biomass wastes. In most of the cases reported so far, graphene has been typically used as additive to enhance its photocatalytic activity of semiconductor materials as consequence of the improved charge separation and visible light harvesting. However, graphene-based materials have demonstrated also intrinsic photocatalytic activity towards solar fuels production, and more specifically for water splitting. The photocatalytic activity of graphene derives from defects generated during synthesis or their introduction through post-synthetic treatments. In this short review, we aim to summarize the most representative examples of graphene based photocatalysts and the different approaches carried out in order to improve the photocatalytic activity towards water splitting. It will be presented that the introduction of defects in the graphenic lattice as well as the incorporation of small amounts of metal or metal oxide nanoparticles on the graphene surface improve the photocatalytic activity of graphene. What is more, a simple one-step preparation method has demonstrated to provide crystal orientation to the nanoparticles strongly grafted on graphene resulting in remarkable photocatalytic properties. These two features, crystal orientation and strong grafting, have been identified as a general methodology to further enhance the photocatalytic activity in graphenebased materials for water splitting. Finally, future prospects in this filed will be also commented. Full article

(This article belongs to the Special Issue Solar Chemicals Production and Environmental Remediation with Semiconductor/Carbon Photocatalysts)

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