Editorial

3 pages, 177 KiB

Open AccessEditorial

Editorial to the Special Issue “Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry”

by Junjiang Zhu

Int. J. Mol. Sci. 2023, 24(8), 7033; https://doi.org/10.3390/ijms24087033 - 11 Apr 2023

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The Special Issue on “Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry” encompasses two aims: one is to remove the pollutants produced in the downstream, and the other is to synthesize chemicals by a green route, avoiding the production of [...] Read more.

The Special Issue on “Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry” encompasses two aims: one is to remove the pollutants produced in the downstream, and the other is to synthesize chemicals by a green route, avoiding the production of pollutants [...] Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

Research

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17 pages, 12961 KiB

Open AccessArticle

Kinetic Aspects of Benzene Degradation over TiO₂-N and Composite Fe/Bi₂WO₆/TiO₂-N Photocatalysts under Irradiation with Visible Light

by Mikhail Lyulyukin, Nikita Kovalevskiy, Andrey Bukhtiyarov, Denis Kozlov and Dmitry Selishchev

Int. J. Mol. Sci. 2023, 24(6), 5693; https://doi.org/10.3390/ijms24065693 - 16 Mar 2023

Cited by 5 | Viewed by 1101

Abstract

In this study, composite materials based on nanocrystalline anatase TiO₂ doped with nitrogen and bismuth tungstate are synthesized using a hydrothermal method. All samples are tested in the oxidation of volatile organic compounds under visible light to find the correlations between their [...] Read more.

In this study, composite materials based on nanocrystalline anatase TiO₂ doped with nitrogen and bismuth tungstate are synthesized using a hydrothermal method. All samples are tested in the oxidation of volatile organic compounds under visible light to find the correlations between their physicochemical characteristics and photocatalytic activity. The kinetic aspects are studied both in batch and continuous-flow reactors, using ethanol and benzene as test compounds. The Bi₂WO₆/TiO₂-N heterostructure enhanced with Fe species efficiently utilizes visible light in the blue region and exhibits much higher activity in the degradation of ethanol vapor than pristine TiO₂-N. However, an increased activity of Fe/Bi₂WO₆/TiO₂-N can have an adverse effect in the degradation of benzene vapor. A temporary deactivation of the photocatalyst can occur at a high concentration of benzene due to the fast accumulation of non-volatile intermediates on its surface. The formed intermediates suppress the adsorption of the initial benzene and substantially increase the time required for its complete removal from the gas phase. An increase in temperature up to 140 °C makes it possible to increase the rate of the overall oxidation process, and the use of the Fe/Bi₂WO₆/TiO₂-N composite improves the selectivity of oxidation compared to pristine TiO₂-N. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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11 pages, 3537 KiB

Open AccessArticle

Enhanced Exciton Effect and Singlet Oxygen Generation Triggered by Tunable Oxygen Vacancies on Bi₂MoO₆ for Efficient Photocatalytic Degradation of Sodium Pentachlorophenol

by Xiao Xu, Xianglong Yang, Yunlong Tao, Wen Zhu, Xing Ding, Junjiang Zhu and Hao Chen

Int. J. Mol. Sci. 2022, 23(23), 15221; https://doi.org/10.3390/ijms232315221 - 02 Dec 2022

Cited by 9 | Viewed by 1572

Abstract

Construction of the tunable oxygen vacancies (OVs) is widely utilized to accelerate molecular oxygen activation for boosting photocatalytic performance. Herein, the in-situ introduction of OVs on Bi₂MoO₆ was accomplished using a calcination treatment in an H₂/Ar atmosphere. The [...] Read more.

Construction of the tunable oxygen vacancies (OVs) is widely utilized to accelerate molecular oxygen activation for boosting photocatalytic performance. Herein, the in-situ introduction of OVs on Bi₂MoO₆ was accomplished using a calcination treatment in an H₂/Ar atmosphere. The introduced OVs can not only facilitate carrier separation, but also strengthen the exciton effect, which accelerates singlet oxygen generation through the energy transfer process. Superior carrier separation and abundant singlet oxygen played a crucial role in favoring photocatalytic NaPCP degradation. The optimal BMO-001-300 sample exhibited the fastest NaPCP degradation rate of 0.033 min⁻¹, about 3.8 times higher than that of the pristine Bi₂MoO₆. NaPCP was effectively degraded and mineralized mainly through dechlorination, dehydroxylation and benzene ring opening. The present work will shed light on the construction and roles of OVs in semiconductor-based photocatalysis and provide a novel insight into ROS-mediated photocatalytic degradation. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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20 pages, 9977 KiB

Open AccessArticle

Synthesis of Co₃O₄ Nanoparticles-Decorated Bi₁₂O₁₇Cl₂ Hierarchical Microspheres for Enhanced Photocatalytic Degradation of RhB and BPA

by Syed Taj Ud Din, Wan-Feng Xie and Woochul Yang

Int. J. Mol. Sci. 2022, 23(23), 15028; https://doi.org/10.3390/ijms232315028 - 30 Nov 2022

Cited by 10 | Viewed by 1716

Abstract

Three-dimensional (3D) hierarchical microspheres of Bi₁₂O₁₇Cl₂ (BOC) were prepared via a facile solvothermal method using a binary solvent for the photocatalytic degradation of Rhodamine-B (RhB) and Bisphenol-A (BPA). Co₃O₄ nanoparticles (NPs)-decorated BOC (Co₃O [...] Read more.

Three-dimensional (3D) hierarchical microspheres of Bi₁₂O₁₇Cl₂ (BOC) were prepared via a facile solvothermal method using a binary solvent for the photocatalytic degradation of Rhodamine-B (RhB) and Bisphenol-A (BPA). Co₃O₄ nanoparticles (NPs)-decorated BOC (Co₃O₄/BOC) heterostructures were synthesized to further enhance their photocatalytic performance. The microstructural, morphological, and compositional characterization showed that the BOC microspheres are composed of thin (~20 nm thick) nanosheets with a 3D hierarchical morphology and a high surface area. Compared to the pure BOC photocatalyst, the 20-Co₃O₄/BOC heterostructure showed enhanced degradation efficiency of RhB (97.4%) and BPA (88.4%). The radical trapping experiments confirmed that superoxide (^•O₂⁻) radicals played a primary role in the photocatalytic degradation of RhB and BPA. The enhanced photocatalytic performances of the hierarchical Co₃O₄/BOC heterostructure are attributable to the synergetic effects of the highly specific surface area, the extension of light absorption to the more visible light region, and the suppression of photoexcited electron-hole recombination. Our developed nanocomposites are beneficial for the construction of other bismuth-based compounds and their heterostructure for use in high-performance photocatalytic applications. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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12 pages, 2572 KiB

Open AccessArticle

Nitrogen-Doped Bismuth Nanosheet as an Efficient Electrocatalyst to CO₂ Reduction for Production of Formate

by Sanxiu Li, Yufei Kang, Chenyang Mo, Yage Peng, Haijun Ma and Juan Peng

Int. J. Mol. Sci. 2022, 23(22), 14485; https://doi.org/10.3390/ijms232214485 - 21 Nov 2022

Cited by 5 | Viewed by 1913

Abstract

Electrochemical CO₂ reduction (CO₂RR) to produce high value-added chemicals or fuels is a promising technology to address the greenhouse effect and energy challenges. Formate is a desirable product of CO₂RR with great economic value. Here, nitrogen-doped bismuth nanosheets [...] Read more.

Electrochemical CO₂ reduction (CO₂RR) to produce high value-added chemicals or fuels is a promising technology to address the greenhouse effect and energy challenges. Formate is a desirable product of CO₂RR with great economic value. Here, nitrogen-doped bismuth nanosheets (N-BiNSs) were prepared by a facile one-step method. The N-BiNSs were used as efficient electrocatalysts for CO₂RR with selective formate production. The N-BiNSs exhibited a high formate Faradic efficiency (FE_formate) of 95.25% at −0.95 V (vs. RHE) with a stable current density of 33.63 mA cm⁻² in 0.5 M KHCO₃. Moreover, the N-BiNSs for CO₂RR yielded a large current density (300 mA cm⁻²) for formate production in a flow-cell measurement, achieving the commercial requirement. The FE_formate of 90% can maintain stability for 14 h of electrolysis. Nitrogen doping could induce charge transfer from the N atom to the Bi atom, thus modulating the electronic structure of N-Bi nanosheets. DFT results demonstrated the N-BiNSs reduced the adsorption energy of the *OCHO intermediate and promoted the mass transfer of charges, thereby improving the CO₂RR with high FE_formate. This study provides a valuable strategy to enhance the catalytic performance of bismuth-based catalysts for CO₂RR by using a nitrogen-doping strategy. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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14 pages, 3834 KiB

Open AccessArticle

Rhombohedral/Cubic In₂O₃ Phase Junction Hybridized with Polymeric Carbon Nitride for Photodegradation of Organic Pollutants

by Xiaorong Cai, Yaning Wang, Shuting Tang, Liuye Mo, Zhe Leng, Yixian Zang, Fei Jing and Shaohong Zang

Int. J. Mol. Sci. 2022, 23(22), 14293; https://doi.org/10.3390/ijms232214293 - 18 Nov 2022

Cited by 3 | Viewed by 1412

Abstract

In recent studies, phase junctions constructed as photocatalysts have been found to possess great prospects for organic degradation with visible light. In this study, we designed an elaborate rhombohedral corundum/cubic In₂O₃ phase junction (named MIO) combined with polymeric carbon nitride [...] Read more.

In recent studies, phase junctions constructed as photocatalysts have been found to possess great prospects for organic degradation with visible light. In this study, we designed an elaborate rhombohedral corundum/cubic In₂O₃ phase junction (named MIO) combined with polymeric carbon nitride (PCN) via an in situ calcination method. The performance of the MIO/PCN composites was measured by photodegradation of Rhodamine B under LED light (λ = 420 nm) irradiation. The excellent performance of MIO/PCN could be attributed to the intimate interface contact between MIO and PCN, which provides a reliable charge transmission channel, thereby improving the separation efficiency of charge carriers. Photocatalytic degradation experiments with different quenchers were also executed. The results suggest that the superoxide anion radicals (O₂⁻) and hydroxyl radicals (·OH) played the main roles in the reaction, as opposed to the other scavengers. Moreover, the stability of the MIO/PCN composites was particularly good in the four cycling photocatalytic reactions. This work illustrates that MOF-modified materials have great potential for solving environmental pollution without creating secondary pollution. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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16 pages, 5118 KiB

Open AccessArticle

Selective Oxidation of Toluene to Benzaldehyde Using Co-ZIF Nano-Catalyst

by Wei Long, Zhilong Chen, Yinfei Huang and Xinping Kang

Int. J. Mol. Sci. 2022, 23(21), 12881; https://doi.org/10.3390/ijms232112881 - 25 Oct 2022

Cited by 3 | Viewed by 1979

Abstract

Nanometer-size Co-ZIF (zeolitic imidazolate frameworks) catalyst was prepared for selective oxidation of toluene to benzaldehyde under mild conditions. The typical characteristics of the metal-organic frameworks (MOFs) material were affirmed by the XRD, SEM, and TEM, the BET surface area of this catalyst was [...] Read more.

Nanometer-size Co-ZIF (zeolitic imidazolate frameworks) catalyst was prepared for selective oxidation of toluene to benzaldehyde under mild conditions. The typical characteristics of the metal-organic frameworks (MOFs) material were affirmed by the XRD, SEM, and TEM, the BET surface area of this catalyst was as high as 924.25 m²/g, and the diameter of particles was near 200 nm from TEM results. The Co metal was coated with 2-methyl glyoxaline, and the crystalline planes were relatively stable. The reaction temperatures, oxygen pressure, mass amount of N-hydroxyphthalimide (NHPI), and reaction time were discussed. The Co-ZIF catalyst gave the best result of 92.30% toluene conversion and 91.31% selectivity to benzaldehyde under 0.12 MPa and 313 K. The addition of a certain amount of NHPI and the smooth oxidate capacity of the catalyst were important factors in the high yield of benzaldehyde. This nanometer-size catalyst showed superior performance for recycling use in the oxidation of toluene. Finally, a possible reaction mechanism was proposed. This new nanometer-size Co-ZIF catalyst will be applied well in the selective oxidation of toluene to benzaldehyde. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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12 pages, 2999 KiB

Open AccessArticle

Dendritic Mesoporous Silica Nanoparticle Supported PtSn Catalysts for Propane Dehydrogenation

by Ning Zhang, Yiou Shan, Jiaxin Song, Xiaoqiang Fan, Lian Kong, Xia Xiao, Zean Xie and Zhen Zhao

Int. J. Mol. Sci. 2022, 23(21), 12724; https://doi.org/10.3390/ijms232112724 - 22 Oct 2022

Cited by 7 | Viewed by 1667

Abstract

PtSn catalysts were synthesized by incipient-wetness impregnation using a dendritic mesoporous silica nanoparticle support. The catalysts were characterized by XRD, N₂ adsorption–desorption, TEM, XPS and Raman, and their catalytic performance for propane dehydrogenation was tested. The influences of Pt/Sn ratios were investigated. [...] Read more.

PtSn catalysts were synthesized by incipient-wetness impregnation using a dendritic mesoporous silica nanoparticle support. The catalysts were characterized by XRD, N₂ adsorption–desorption, TEM, XPS and Raman, and their catalytic performance for propane dehydrogenation was tested. The influences of Pt/Sn ratios were investigated. Changing the Pt/Sn ratios influences the interaction between Pt and Sn. The catalyst with a Pt/Sn ratio of 1:2 possesses the highest interaction between Pt and Sn. The best catalytic performance was obtained for the Pt₁Sn₂/DMSN catalyst with an initial propane conversion of 34.9%. The good catalytic performance of this catalyst is ascribed to the small nanoparticle size of PtSn and the favorable chemical state and dispersion degree of Pt and Sn species. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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13 pages, 3477 KiB

Open AccessArticle

Solid Fe Resources Separated from Rolling Oil Sludge for CO Oxidation

by Wei Gao, Sai Tang, Ting Wu, Jianhong Wu, Kai Cheng and Minggui Xia

Int. J. Mol. Sci. 2022, 23(20), 12134; https://doi.org/10.3390/ijms232012134 - 12 Oct 2022

Cited by 3 | Viewed by 1300

Abstract

The efficient recycling of valuable resources from rolling oil sludge (ROS) to gain new uses remains a formidable challenge. In this study, we reported the recycling of solid Fe resources from ROS by a catalytic hydrogenation technique and its catalytic performance for CO [...] Read more.

The efficient recycling of valuable resources from rolling oil sludge (ROS) to gain new uses remains a formidable challenge. In this study, we reported the recycling of solid Fe resources from ROS by a catalytic hydrogenation technique and its catalytic performance for CO oxidation. The solid Fe resources, after calcination in air (Fe₂O₃-H), exhibited comparable activity to those prepared by the calcinations of ferric nitrate (Fe₂O₃-C), suggesting that the solid resources have excellent recycling value when used as raw materials for CO oxidation catalyst preparation. Further studies to improve the catalytic performance by supporting the materials on high surface area 13X zeolite and by pretreating the materials with CO atmosphere, showed that the CO pretreatment greatly improved the CO oxidation activity and the best activity was achieved on the 20 wt.%Fe₂O₃-H/13X sample with complete CO conversion at 250 °C. CO pretreatment could produce more oxygen vacancies, facilitating O₂ activation, and thus accelerate the CO oxidation reaction rate. The excellent reducibility and sufficient O₂ adsorption amount were also favorable for its performance. The recycling of solid Fe resources from ROS is quite promising for CO oxidation applications. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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Review

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32 pages, 8135 KiB

Open AccessReview

Research Progress on Graphitic Carbon Nitride/Metal Oxide Composites: Synthesis and Photocatalytic Applications

by Hao Lin, Yao Xiao, Aixia Geng, Huiting Bi, Xiao Xu, Xuelian Xu and Junjiang Zhu

Int. J. Mol. Sci. 2022, 23(21), 12979; https://doi.org/10.3390/ijms232112979 - 26 Oct 2022

Cited by 5 | Viewed by 2454

Abstract

Although graphitic carbon nitride (g-C₃N₄) has been reported for several decades, it is still an active material at the present time owing to its amazing properties exhibited in many applications, including photocatalysis. With the rapid development of characterization techniques, [...] Read more.

Although graphitic carbon nitride (g-C₃N₄) has been reported for several decades, it is still an active material at the present time owing to its amazing properties exhibited in many applications, including photocatalysis. With the rapid development of characterization techniques, in-depth exploration has been conducted to reveal and utilize the natural properties of g-C₃N₄ through modifications. Among these, the assembly of g-C₃N₄ with metal oxides is an effective strategy which can not only improve electron–hole separation efficiency by forming a polymer–inorganic heterojunction, but also compensate for the redox capabilities of g-C₃N₄ owing to the varied oxidation states of metal ions, enhancing its photocatalytic performance. Herein, we summarized the research progress on the synthesis of g-C₃N₄ and its coupling with single- or multiple-metal oxides, and its photocatalytic applications in energy production and environmental protection, including the splitting of water to hydrogen, the reduction of CO₂ to valuable fuels, the degradation of organic pollutants and the disinfection of bacteria. At the end, challenges and prospects in the synthesis and photocatalytic application of g-C₃N₄-based composites are proposed and an outlook is given. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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19 pages, 4998 KiB

Open AccessReview

Photocatalytic Degradation of Some Typical Antibiotics: Recent Advances and Future Outlooks

by Xue Bai, Wanyu Chen, Bao Wang, Tianxiao Sun, Bin Wu and Yuheng Wang

Int. J. Mol. Sci. 2022, 23(15), 8130; https://doi.org/10.3390/ijms23158130 - 24 Jul 2022

Cited by 35 | Viewed by 4468

Abstract

The existence of antibiotics in the environment can trigger a number of issues by fostering the widespread development of antimicrobial resistance. Currently, the most popular techniques for removing antibiotic pollutants from water include physical adsorption, flocculation, and chemical oxidation, however, these processes usually [...] Read more.

The existence of antibiotics in the environment can trigger a number of issues by fostering the widespread development of antimicrobial resistance. Currently, the most popular techniques for removing antibiotic pollutants from water include physical adsorption, flocculation, and chemical oxidation, however, these processes usually leave a significant quantity of chemical reagents and polymer electrolytes in the water, which can lead to difficulty post-treating unmanageable deposits. Furthermore, though cost-effectiveness, efficiency, reaction conditions, and nontoxicity during the degradation of antibiotics are hurdles to overcome, a variety of photocatalysts can be used to degrade pollutant residuals, allowing for a number of potential solutions to these issues. Thus, the urgent need for effective and rapid processes for photocatalytic degradation leads to an increased interest in finding more sustainable catalysts for antibiotic degradation. In this review, we provide an overview of the removal of pharmaceutical antibiotics through photocatalysis, and detail recent progress using different nanostructure-based photocatalysts. We also review the possible sources of antibiotic pollutants released through the ecological chain and the consequences and damages caused by antibiotics in wastewater on the environment and human health. The fundamental dynamic processes of nanomaterials and the degradation mechanisms of antibiotics are then discussed, and recent studies regarding different photocatalytic materials for the degradation of some typical and commonly used antibiotics are comprehensively summarized. Finally, major challenges and future opportunities for the photocatalytic degradation of commonly used antibiotics are highlighted. Full article

(This article belongs to the Special Issue Molecular Aspects in Catalytic Materials for Pollution Elimination and Green Chemistry)

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