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Volume 14
Issue 6
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Catalysts, Volume 14, Issue 6 (June 2024) – 60 articles

Cover Story (view full-size image): Carbon dioxide oxidative dehydrogenation of propane (CO2-ODHP) has attracted lots of attention in recent years, because of its benefits not only in olefin production but also in CO2 emission control. In this study, a series of Cr-M(M=Zr, La, Fe)-ZSM-5 was prepared using the impregnation method, wherein Cr-Zr-ZSM-5 was the most effective. To further improve its reaction performance, the composite zeolite catalyst of Cr3%Zr2%-ZSM-5@SBA-15 was prepared via hydrothermal synthesis, which achieves a C3H8 conversion of 76.9% and an olefin yield of 1.72 × 103 µmol·g−1 cat·h−1. The introduction of the additive metal Zr as well as the formation of composite zeolite can enhance the distribution of Cr6+ species (as the active site) as well as its redox ability. Generally, the present work contributes to other highly efficient CO2-ODHP catalyst designs. View this paper
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16 pages, 5934 KiB  
Article
Modification of α-Fe2O3 Nanoparticles with Carbon Layer for Robust Photo-Fenton Catalytic Degradation of Methyl Orange
by Muhammad Qasim, Mohamed A. Ghanem, Xuecheng Cao and Xiaojie Li
Catalysts 2024, 14(6), 393; https://doi.org/10.3390/catal14060393 - 20 Jun 2024
Cited by 1 | Viewed by 1110
Abstract
The degradation of organic dyes poses a significant challenge in achieving sustainable environmental solutions, given their extensive usage across various industries. Iron oxide (Fe2O3) nanoparticles are studied as a reliable technique for remediating dye degradation. The objective of this [...] Read more.
The degradation of organic dyes poses a significant challenge in achieving sustainable environmental solutions, given their extensive usage across various industries. Iron oxide (Fe2O3) nanoparticles are studied as a reliable technique for remediating dye degradation. The objective of this research is to improve methods of nanomaterial-based environmental remediation. The solvothermal technique is used to synthesize carbon-modified Fe2O3 nanoparticles that exhibit the capability to modify their size morphology and increase reactivity, and stability for MO photodegradation. Their inherent qualities render them highly advantageous for biomedical applications, energy storage, environmental remediation, and catalysis. The mean crystallite size of the modified Fe2O3 nanoparticles is approximately 20 nm. These photocatalysts are tested for their ability to degrade methyl orange (MO) under Visible light radiation and in presence of hydrogen peroxide reagent. The optimal degradation efficiency (97%) is achieved with Fe2O3@C in the presence of H2O2 by meticulously controlling the pH, irradiation time, and photocatalyst dosage. The enhanced photocatalytic activity of the Fe2O3@C nanoparticles, compared to pure Fe2O3, is attributed to the conductive carbon layer, which significantly reduces electron-hole recombination rates. To summarize, Fe2O3@C nanoparticles not only offer a promising technique for the degradation of MO dye pollutants but also have an advantage for environmental remediation due to their increased stability and reactivity. Full article
(This article belongs to the Special Issue Cutting-Edge Photocatalysis)
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15 pages, 2672 KiB  
Article
Synthesis of CBO (Co3O4-Bi2O3) Heterogeneous Photocatalyst for Degradation of Fipronil and Acetochlor Pesticides in Aqueous Medium
by Muhammad Saeed, Sandeep Panchal, Majed A. Bajaber, Ahlam A. Alalwiat, Ahmed Ezzat Ahmed, Ujala Razzaq, Hafiza Zahra Rab Nawaz and Farhat Hussain
Catalysts 2024, 14(6), 392; https://doi.org/10.3390/catal14060392 - 19 Jun 2024
Viewed by 1004
Abstract
The excessive use of pesticides has led to the harmful contamination of water reservoirs. Visible-light-driven photocatalysis is one of the suitable methods for the removal of pesticides from water. Herein, the development of CBO (Co3O4-Bi2O3) [...] Read more.
The excessive use of pesticides has led to the harmful contamination of water reservoirs. Visible-light-driven photocatalysis is one of the suitable methods for the removal of pesticides from water. Herein, the development of CBO (Co3O4-Bi2O3) as a heterogeneous catalyst for the visible light-assisted degradation of Fipronil and Acetochlor pesticides is reported. After synthesis via coprecipitation using cobalt (II) nitrate hexahydrate (Co(NO3)2·6H2O), bismuth (III) nitrate pentahydrate (Bi(NO3)3·5H2O) and sodium hydroxide (NaOH) as precursor materials, the prepared CBO was characterized using advanced techniques including XRD, EDS, TEM, SEM, FTIR, and surface area and pore size analysis. Then, it was employed as a photocatalyst for the degradation of Fipronil and Acetochlor pesticides under visible light irradiation. The complete removal of Fipronil and Acetochlor pesticides was observed over CBO photocatalyst using 50 mL (100 mg/L) of each pesticide separately within 120 min of reaction. The reaction kinetics was investigated using a non-linear method of analysis using the Solver add-in. The prepared CBO exhibited a 2.8-fold and 2-fold catalytic performance in the photodegradation of selected pesticides than Co3O4 and Bi2O3 did, respectively. Full article
(This article belongs to the Special Issue Microporous and Mesoporous Materials for Catalytic Applications)
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13 pages, 3461 KiB  
Article
Effect of NaOH Concentration on Rapidly Quenched Cu–Al Alloy-Derived Cu Catalyst for CO2 Hydrogenation to CH3OH
by Xuancheng Liu, Dong Sun, Yushan Ji, Sijie Zu, Yan Pei, Shirun Yan, Minghua Qiao, Xiaoxin Zhang and Baoning Zong
Catalysts 2024, 14(6), 391; https://doi.org/10.3390/catal14060391 - 19 Jun 2024
Viewed by 823
Abstract
By utilizing greenhouse gas CO2 and renewable energy-sourced H2 to produce methanol, the “methanol economy” can replace fossil fuels and H2 as the energy storage medium, which not only reduces CO2 emissions, but also mitigates the energy shortage issue. [...] Read more.
By utilizing greenhouse gas CO2 and renewable energy-sourced H2 to produce methanol, the “methanol economy” can replace fossil fuels and H2 as the energy storage medium, which not only reduces CO2 emissions, but also mitigates the energy shortage issue. However, the traditional Cu-based catalysts for CO2-to-methanol conversion suffer from low activity at low temperature and high vulnerability to sintering and deactivation. In this contribution, rapidly quenched skeletal Cu catalysts (RQ Cu) are prepared by leaching the RQ Cu–Al alloy with NaOH aqueous solutions of different concentrations. It is found that high NaOH concentration of 10 wt% favors the preparation of the RQ Cu-10 catalyst with higher porosity, lower residual Al content, and larger active Cu surface area (SCu) than the RQ Cu-3 catalyst leached with 3 wt% of NaOH solution. However, in aqueous-phase CO2 hydrogenation at 473 K and 4.0 MPa, the CO2 conversion over the RQ Cu-3 catalyst is more than two times greater than that over the RQ Cu-10 catalyst, and the selectivity and productivity of methanol are 1.20 and 2.69 times of the corresponding values over the RQ Cu-10 catalyst. At 5.0 MPa, the selectivity and productivity of methanol are further boosted to 97.9% and 1.329 mmol gCu–1 h–1 on the RQ Cu-3 catalyst. It is identified that the SCu of the RQ Cu-3 catalyst is well preserved after reaction, while dramatic growth of the Cu crystallites occurs for the RQ Cu-10 catalyst. The better catalytic performance and stability of the RQ Cu-3 catalyst are tentatively attributed to the presence of more residual Al species by using NaOH solution with lower concentration for Al leaching, which acts as the dispersant for the Cu crystallites during the reaction. Full article
(This article belongs to the Special Issue Exclusive Papers in Green Photocatalysis from China)
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16 pages, 4034 KiB  
Article
Exploring the Effect of the Solvothermal Time on the Structural Properties and Catalytic Activity of Cu-ZnO-ZrO2 Catalysts Synthesized by the Solvothermal Method for CO2 Hydrogenation to Methanol
by Jian Han, Yannan Liang, Jun Yu, Guisheng Wu and Dongsen Mao
Catalysts 2024, 14(6), 390; https://doi.org/10.3390/catal14060390 - 18 Jun 2024
Viewed by 895
Abstract
A series of Cu-ZnO-ZrO2 (CCZ) catalysts were prepared by the solvothermal method with different solvothermal times (1 h, 3 h, 6 h, and 12 h). The physicochemical properties of these catalysts and the catalytic performance for CO2 hydrogenation to methanol were [...] Read more.
A series of Cu-ZnO-ZrO2 (CCZ) catalysts were prepared by the solvothermal method with different solvothermal times (1 h, 3 h, 6 h, and 12 h). The physicochemical properties of these catalysts and the catalytic performance for CO2 hydrogenation to methanol were studied. The highest methanol yield was achieved when the solvothermal time was 6 h (CCZ-6). Furthermore, we found that the copper surface area (SCu) increases and then decreases with an increase in the solvothermal time and that there is a strong correlation between the methanol yield and the SCu. This research highlights the crucial influence of the solvothermal time on the structure and catalytic behavior of Cu-ZnO-ZrO2 catalysts, providing a valuable reference for the development of efficient catalysts. Full article
(This article belongs to the Special Issue Topical Advisory Panel Members' Collection Series: Catalytic Materials for the Production of Renewable Fuels)
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15 pages, 4804 KiB  
Article
Influence of Oxidation Temperature on the Regeneration of a Commercial Pt-Sn/Al2O3 Propane Dehydrogenation Catalyst
by Chao Zhang, Mingliang Tao, Zhijun Sui, Nihong An, Yafeng Shen and Xinggui Zhou
Catalysts 2024, 14(6), 389; https://doi.org/10.3390/catal14060389 - 18 Jun 2024
Viewed by 913
Abstract
In the propane dehydrogenation process, the structure and catalytic performance stability of the catalyst are determined by its regeneration process, which includes oxidation of coke and oxychlorination to redisperse the supported metal particles. A commercial Pt-Sn catalyst was used in this work to [...] Read more.
In the propane dehydrogenation process, the structure and catalytic performance stability of the catalyst are determined by its regeneration process, which includes oxidation of coke and oxychlorination to redisperse the supported metal particles. A commercial Pt-Sn catalyst was used in this work to investigate the impact of oxidation temperature on oxychlorination performance. The catalysts after oxidation and oxychlorination were characterized by H2-TPR, CO-DRIFTS, HAADF-STEM, XPS, and CO chemisorption. It was found that mild sintering of Pt occurred during oxidation in the temperature range of 550–650 °C, and the catalyst could be fully restored in the subsequent oxychlorination treatment. Upon oxidation of the catalyst at 700 °C, a severe aggregation of Pt and SnOx could be observed, and the catalyst could not be fully regenerated under the given oxychlorination conditions. However, PDH catalyst deactivation caused by sintering is not irreversible. By tailoring the oxychlorination conditions, the detrimental effect of high oxidation temperature on regeneration could be ruled out. During the oxidation and oxychlorination treatment, the metal tends to migrate to anchor on sites with stronger metal–support interaction, which was helpful for enhancing the catalytic activity. Full article
(This article belongs to the Section Catalytic Materials)
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49 pages, 2859 KiB  
Review
Recent Advances in Layered MX2-Based Materials (M = Mo, W and X = S, Se, Te) for Emerging Optoelectronic and Photo(electro)catalytic Applications
by Felipe M. Pinto, Mary C. M. D. de Conti, Wyllamanney S. Pereira, Júlio C. Sczancoski, Marina Medina, Patricia G. Corradini, Juliana F. de Brito, André E. Nogueira, Márcio S. Góes, Odair P. Ferreira, Lucia H. Mascaro, Fernando Wypych and Felipe A. La Porta
Catalysts 2024, 14(6), 388; https://doi.org/10.3390/catal14060388 - 17 Jun 2024
Cited by 1 | Viewed by 2934
Abstract
Transition metal dichalcogenides (TMDCs), represented by MX2 (where M = Mo, W and X = S, Se, and Te), and more recently, their moiré superlattices (i.e., formed by superimposing layers of TMDCs with different rotation angles) have attracted considerable interest due to [...] Read more.
Transition metal dichalcogenides (TMDCs), represented by MX2 (where M = Mo, W and X = S, Se, and Te), and more recently, their moiré superlattices (i.e., formed by superimposing layers of TMDCs with different rotation angles) have attracted considerable interest due to their excellent physical properties and unique nanoscale functionalities. Compared to graphene, the literature indicates that TMDCs offer a competitive advantage in optoelectronic technologies, primarily owing to their compositionally controlled non-zero bandgap. These two-dimensional (2D) nanostructured single or multiple layers exhibit remarkable properties that differ from their bulk counterparts. Moreover, stacking different TMDC monolayers also forms heterostructures and introduces unique quantum effects and extraordinary electronic properties, which is particularly promising for next-generation optoelectronic devices and photo(electro)catalytic applications. Therefore, in this review, we also highlight the new possibilities in the formation of 2D/2D heterostructures of MX2-based materials with moiré patterns and discuss the main critical challenges related to the synthesis and large-scale applications of layered MX2 and MX2-based composites to spur significant advances in emerging optoelectronic and photo(electro)catalytic applications. Full article
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29 pages, 4102 KiB  
Article
Synthesis and Characterization of New Bases Derived from Nitrophenylpyrazoles, Coordination to Palladium and Antifungal Activity and Catalytic Activity in Mizoroki–Heck Reactions
by Jennifer Londoño-Salazar, Andrés Restrepo-Acevedo, John Eduard Torres, Rodrigo Abonia, Laura Svetaz, Susana A. Zacchino, Ronan Le Lagadec and Fernando Cuenú-Cabezas
Catalysts 2024, 14(6), 387; https://doi.org/10.3390/catal14060387 - 16 Jun 2024
Cited by 1 | Viewed by 1323
Abstract
In this study, we report the synthesis of eight Schiff bases (3–10) type N-heterocycle (N-het) using conventional refluxing conditions as well as different eco-friendly techniques such as grinding, thermal fusion, microwave irradiation (MWI) and ultrasound, all [...] Read more.
In this study, we report the synthesis of eight Schiff bases (3–10) type N-heterocycle (N-het) using conventional refluxing conditions as well as different eco-friendly techniques such as grinding, thermal fusion, microwave irradiation (MWI) and ultrasound, all of them in the presence of a catalytic amount of acetic acid. These procedures had the additional advantage of being environmentally friendly and high-yield, making these protocols an alternative for Schiff-base syntheses. The obtained Schiff bases were coordinated to palladium, generating new complexes of type [Pd2Cl4(N-het)2]. Complexes [Pd2Cl4(5)2] and [Pd2Cl4(9)2] showed high activity and selectivity for a model Mizoroki–Heck C-C coupling reaction of styrene with iodobenzene and bromobenzaldehydes. All compounds and complexes were evaluated for antifungal activity against clinically important fungi such as Candida albicans and Cryptococcus neoformans. Although the Schiff bases (3–10) showed low antifungal activity against both fungi, some of their palladium complexes such as [Pd2Cl4(3)2], [Pd2Cl4(5)2], [Pd2Cl4(8)2] and [Pd2Cl4(10)2] showed comparatively higher antifungal effects mainly against C. neoformans. The product of the Mizoroki–Heck-type C-C coupling reactions, 4-styrylbenzaldehyde, was isolated and purified to be later used in the synthesis of four new nitrophenylpyrazole derivatives of styrylimine, which also displayed antifungal activity, especially against C. neoformans. Full article
(This article belongs to the Special Issue Catalysis and Coordination Chemistry)
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16 pages, 8120 KiB  
Article
Methanol Reforming over Cu-Ce-Al Catalysts Prepared by Solution Combustion Synthesis Method
by Yernur B. Assylbekov, Galina Xanthopoulou, Svetlana A. Tungatarova, Tolkyn S. Baizhumanova, Yermek A. Aubakirov and Manapkhan Zhumabek
Catalysts 2024, 14(6), 386; https://doi.org/10.3390/catal14060386 - 15 Jun 2024
Cited by 1 | Viewed by 868
Abstract
The demand for environmentally friendly types of energy is growing all over the world, which naturally increases the intensity of studies on fuel mixtures that have high contents of hydrogen. In this case, methanol steam reforming is a leading effective research area, as [...] Read more.
The demand for environmentally friendly types of energy is growing all over the world, which naturally increases the intensity of studies on fuel mixtures that have high contents of hydrogen. In this case, methanol steam reforming is a leading effective research area, as it is a process with low energy consumption. The results of the steam reforming of methanol on synthesized catalysts by the solution combustion synthesis (SCS), self-propagating high-temperature synthesis (SHS), and moisture impregnation capacity methods are presented. A study was conducted to evaluate the activity of Cu-Ce-Al catalysts with varying ratios of components for hydrogen production, comparing the SCS method with the other mentioned methods. The methanol conversion reached 99% and the selectivity of H2 was 88% at 500 °C. The study showed that the replacement of Al3+ ions with Cu2+ and Ce3+ cations leads to the formation of spinels, such as CuAl2O4 and CeAlO3. As a consequence, the CuAl2O4 and CeAlO3 lattice parameters increase because of the difference in the ionic radii of Al3+ (0.53 Å), Cu2+ (0.73 Å), and Ce3+ (1.07 Å). Advantages of SCS catalysts in the process of the steam reforming of methanol have been demonstrated. The goal of this research is to create a new catalyst for methanol’s conversion into hydrogen-containing fuel mixtures, the production of which, in the future, will be a huge step in the transition to more energy-efficient and environmentally friendly methods of their synthesis. Full article
(This article belongs to the Special Issue New Catalysts and Reactors for the Synthesis or Conversion of Methanol, 2nd Edition)
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16 pages, 4836 KiB  
Article
Design and Optimization of Critical-Raw-Material-Free Electrodes towards the Performance Enhancement of Microbial Fuel Cells
by Khair Un Nisa, Williane da Silva Freitas, Alessandra D’Epifanio and Barbara Mecheri
Catalysts 2024, 14(6), 385; https://doi.org/10.3390/catal14060385 - 15 Jun 2024
Viewed by 1139
Abstract
Microbial fuel cells (MFCs) are sustainable energy recovery systems because they use organic waste as biofuel. Using critical raw materials (CRMs), like platinum-group metals, at the cathode side threatens MFC technology’s sustainability and raises costs. By developing an efficient electrode design for MFC [...] Read more.
Microbial fuel cells (MFCs) are sustainable energy recovery systems because they use organic waste as biofuel. Using critical raw materials (CRMs), like platinum-group metals, at the cathode side threatens MFC technology’s sustainability and raises costs. By developing an efficient electrode design for MFC performance enhancement, CRM-based cathodic catalysts should be replaced with CRM-free materials. This work proposes developing and optimizing iron-based air cathodes for enhancing oxygen reduction in MFCs. By subjecting iron phthalocyanine and carbon black pearls to controlled thermal treatments, we obtained Fe-based electrocatalysts combining high surface area (628 m2 g−1) and catalytic activity for O2 reduction at near-neutral pH. The electrocatalysts were integrated on carbon cloth and carbon paper to obtain gas diffusion electrodes whose architecture was optimized to maximize MFC performance. Excellent cell performance was achieved with the carbon-paper-based cathode modified with the Fe-based electrocatalysts (maximum power density-PDmax = 1028 mWm−2) compared to a traditional electrode design based on carbon cloth (619 mWm−2), indicating the optimized cathodes as promising electrodes for energy recovery in an MFC application. Full article
(This article belongs to the Section Electrocatalysis)
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12 pages, 5195 KiB  
Article
Pt/CB-Catalyzed Chemoselective Hydrogenation Using In Situ-Generated Hydrogen by Microwave-Mediated Dehydrogenation of Methylcyclohexane under Continuous-Flow Conditions
by Naoya Sakurada, Takanori Kitazono, Takashi Ikawa, Tsuyoshi Yamada and Hironao Sajiki
Catalysts 2024, 14(6), 384; https://doi.org/10.3390/catal14060384 - 15 Jun 2024
Cited by 1 | Viewed by 1294
Abstract
Hydrogen gas (H2) has attracted attention as a next-generation clean energy source. Its efficient and safe preparation and utilization are crucial in both the industry and organic chemistry research. In this study, a Pt/CB (platinum on carbon bead)-catalyzed MW-mediated continuous-flow hydrogenation [...] Read more.
Hydrogen gas (H2) has attracted attention as a next-generation clean energy source. Its efficient and safe preparation and utilization are crucial in both the industry and organic chemistry research. In this study, a Pt/CB (platinum on carbon bead)-catalyzed MW-mediated continuous-flow hydrogenation reaction was developed using methylcyclohexane (MCH) as the reducing agent (hydrogen carrier). Alkynes, alkenes, nitro groups, benzyl esters, and aromatic chlorides were chemoselectively hydrogenated using Pt/CB under MW-assisted continuous-flow conditions. This methodology represents a safe and energy-efficient hydrogenation process, as it eliminates the need for an external hydrogen gas supply or heating jackets as a heating medium. The further application of MW-mediated continuous-flow hydrogenation reactions is a viable option for the efficient generation and utilization of sustainable energy. Full article
(This article belongs to the Section Catalytic Materials)
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21 pages, 2709 KiB  
Article
Influence of 0.25% Indium Addition to Ni/CeO2 Catalysts for Dry Reforming of Methane
by Anita Horváth, Andrea Beck, Miklós Németh, György Sáfrán, Matevž Roškarič, Gregor Žerjav and Albin Pintar
Catalysts 2024, 14(6), 383; https://doi.org/10.3390/catal14060383 - 15 Jun 2024
Viewed by 1281
Abstract
In this study, the surface and textural properties as well as the catalytic performance of Ni/CeO2 and NiIn/CeO2 catalysts prepared by wet impregnation (WI) and deposition–precipitation (DP) are investigated. The addition of Ni (3.0 wt.%) resulted in a decrease in the [...] Read more.
In this study, the surface and textural properties as well as the catalytic performance of Ni/CeO2 and NiIn/CeO2 catalysts prepared by wet impregnation (WI) and deposition–precipitation (DP) are investigated. The addition of Ni (3.0 wt.%) resulted in a decrease in the specific surface area and pore volume in the case of the WI method, possibly due to a blockage of mesopores. A minimal addition of In (0.25 wt.%) caused a further decrease in the surface area in both cases. XRD analysis showed that Ni deposited on CeO2 by DP resulted in some lattice incorporation, affecting the crystallinity of the support. The H2-TPR profiles altered depending on the different ways of Ni and In introduction. STEM-EDS-derived elemental maps indicated that the Ni and NiIn particles deposited on CeO2 using the DP method were somewhat smaller than in the WI synthesis. A comprehensive CO-DRIFTS analysis proved a direct Ni-In interaction in bimetallic samples, leading to the formation of a surface NiIn alloy. Ni/CeO2 catalysts showed a higher activity in the process of dry reforming of methane (DRM) than the bimetallic counterparts at 650 °C, with the Ni_DP sample performing slightly better. However, the Ni_DP catalyst showed significant coking, which was drastically reduced by the addition of In. The agglomeration of Ni and/or NiIn particles during the 6 h DRM reaction somewhat impaired the catalyst performance. Overall, this study highlights the intricate relationship between the catalyst preparation, surface properties and catalytic performance in the DRM reaction and emphasizes the beneficial role of In addition in reducing the coking of the monometallic catalyst and the critical location and surface morphology of nickel nanoparticles decorated with indium and in contact with ceria. Full article
(This article belongs to the Special Issue Study of Novel Catalysts for Methane Conversion)
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10 pages, 2680 KiB  
Article
First Principles Study of O2 Dissociative Adsorption on Pt-Skin Pt3Cu(111) Surface
by Yanlin Yu, Huaizhang Gu, Mingan Fu, Ying Wang, Xin Fan, Mingqu Zhang and Guojiang Wu
Catalysts 2024, 14(6), 382; https://doi.org/10.3390/catal14060382 - 14 Jun 2024
Viewed by 793
Abstract
The O2 dissociative adsorption serves as a pivotal criterion for assessing the efficacy of oxygen reduction catalysts. We conducted a systematic investigation into O2 dissociative adsorption on the Pt-skin Pt3Cu(111) surface by means of the density functional theory (DFT). [...] Read more.
The O2 dissociative adsorption serves as a pivotal criterion for assessing the efficacy of oxygen reduction catalysts. We conducted a systematic investigation into O2 dissociative adsorption on the Pt-skin Pt3Cu(111) surface by means of the density functional theory (DFT). The computational findings reveal that the O2 adsorption on Pt-skin Pt3Cu(111) surface exhibits comparatively lower stability when contrasted with that on the Pt(111) surface. For O2 dissociation, two paths have been identified. One progresses from the t-f-b state towards the generation of two oxygen atoms situated within nearest-neighbour hcp sites. The other commences from the t-b-t state, leading to the generation of two oxygen atoms occupying nearest-neighbour fcc sites. Moreover, the analysis of the energy barrier associated with O2 dissociation indicates that O2 on the Pt-skin Pt3Cu(111) surface is more difficult to dissociate than on the Pt(111) surface. This study can offer a valuable guide for the practical application of high-performance oxygen reduction catalysts. Full article
(This article belongs to the Section Computational Catalysis)
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20 pages, 4104 KiB  
Review
Review of TiO2 as Desulfurization Catalyst for Petroleum
by Zahraa A. Hamza, Jamal J. Dawood and Murtadha Abbas Jabbar
Catalysts 2024, 14(6), 381; https://doi.org/10.3390/catal14060381 - 14 Jun 2024
Cited by 1 | Viewed by 1000
Abstract
In the relentless pursuit of sustainable energy solutions, the petroleum industry faces the imperative challenge of mitigating sulfur emissions. This comprehensive review scrutinizes Titanium Dioxide (TiO2) as an extraordinary catalyst, pushing the boundaries of desulfurization performance in petroleum refining. The abstract [...] Read more.
In the relentless pursuit of sustainable energy solutions, the petroleum industry faces the imperative challenge of mitigating sulfur emissions. This comprehensive review scrutinizes Titanium Dioxide (TiO2) as an extraordinary catalyst, pushing the boundaries of desulfurization performance in petroleum refining. The abstract begins by underscoring the urgent need for advanced desulfurization technologies, driven by stringent environmental mandates and escalating global energy demands. The spotlight then shifts to the unparalleled physicochemical attributes of TiO2, showcasing its inherent advantages such as exceptional surface area, stability, and photocatalytic process. A profound exploration of TiO2’s catalytic mechanisms follows, unraveling its capacity to disintegrate stubborn sulfur–carbon bonds, thereby elevating desulfurization efficiency to unprecedented levels. This review meticulously dissects diverse forms of TiO2, ranging from nanoparticles to mesoporous structures, and provides a critical analysis of their respective strengths and limitations in catalyzing sulfur removal. Delving into operational nuances, this review examines the impact of temperature, pressure, and catalyst loading on TiO2 performance, offering crucial insights for optimizing desulfurization processes. The narrative then unfolds to explore cutting-edge developments in TiO2-based catalysts, encompassing ingenious modifications, composites, and hybrid materials designed to augment catalytic activity and selectivity. Anticipating the road ahead, this review contemplates the challenges and prospects of deploying TiO2 on an industrial scale, pointing toward avenues for future research and development. This abstract encapsulates a wealth of knowledge, serving as an indispensable resource for researchers, engineers, and policymakers navigating the dynamic landscape of sustainable petroleum refining. TiO2 emerges as a transformative force, propelling the industry toward cleaner, greener, and more efficient energy production. Full article
(This article belongs to the Section Environmental Catalysis)
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16 pages, 7758 KiB  
Article
Enhanced Orange II Removal Using Fe/Mn/Mg2-LDH Activated Peroxymonosulfate: Synergistic Radical Oxidation and Adsorption
by Yajie Wang, Cui Qiu, Peng Cheng, Yuqing Li, Yunlong Ma, Xiuzhen Tao, Bo Weng and Gilles Mailhot
Catalysts 2024, 14(6), 380; https://doi.org/10.3390/catal14060380 - 14 Jun 2024
Cited by 2 | Viewed by 881
Abstract
In this study, Fe/Mn/Mg2-LDH was utilized for the first time as a catalyst for peroxymonosulfate (PMS) activation to facilitate the removal of Orange II. This composite was characterized using various techniques, such as XRD, FTIR, SEM-EDS, BET, and XPS. The results [...] Read more.
In this study, Fe/Mn/Mg2-LDH was utilized for the first time as a catalyst for peroxymonosulfate (PMS) activation to facilitate the removal of Orange II. This composite was characterized using various techniques, such as XRD, FTIR, SEM-EDS, BET, and XPS. The results revealed a well-defined lamellar structure of Fe/Mn/Mg2-LDH with a metal molar ratio of Fe/Mn/Mg at 1:1:2. Moreover, the structural stability of Fe/Mn/Mg2-LDH was confirmed through the XRD, FTIR, and SEM. Fe/Mn/Mg2-LDH exhibited a good adsorption capacity towards Orange II and highly efficient PMS activation. The optimal removal efficiency of Orange II (98%) was achieved under the conditions of pH 7.0, [PMS] = 1.0 mmol L−1, [Fe/Mn/Mg₂-LDH] = 1.6 g L−1, and [Orange II] = 50 μM. Additionally, this system demonstrated good adaptability across a wide pH range. The presence of Cl− and humic acids (HA) did not significantly inhibit Orange II removal, whereas inhibitory effects were observed in the presence of CO32− and PO43−. The removal mechanism of Orange II was attributed to a synergy of adsorption and oxidation processes, wherein the generated surface radicals (SO4•−ads and HO•ads) on the surface of the Fe/Mn/Mg2-LDH played a predominant role. Furthermore, the Fe/Mn/Mg2-LDH exhibited good reusability, maintaining a removal rate of 90% over five cycles of recycling. The Fe/Mn/Mg2-LDH/PMS system shows promising potential for the treatment of wastewater contaminated with refractory organic pollutants. Full article
(This article belongs to the Section Environmental Catalysis)
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16 pages, 7158 KiB  
Article
Selection of Putative Polyester Hydrolases from the Metagenome of Los Humeros Geothermal Field by Means of In Silico Probes
by Rocio Solis-Palacios, Graciela Espinosa-Luna, Carolina Peña-Montes, Rodolfo Quintana-Castro, María Guadalupe Sánchez-Otero and Rosa María Oliart-Ros
Catalysts 2024, 14(6), 379; https://doi.org/10.3390/catal14060379 - 14 Jun 2024
Viewed by 985
Abstract
Hydrolases are the most popular enzymes, and among the most valuable in biotechnological applications. Some hydrolases, such as lipases, esterases, proteases, cellulases and amylases, are used in the food industry and the production of biopharmaceuticals, biofuels, biopolymers and detergents. Of special interest are [...] Read more.
Hydrolases are the most popular enzymes, and among the most valuable in biotechnological applications. Some hydrolases, such as lipases, esterases, proteases, cellulases and amylases, are used in the food industry and the production of biopharmaceuticals, biofuels, biopolymers and detergents. Of special interest are those obtained from thermophilic microorganisms. Although there is great microbial diversity in extreme environments, the investigations aimed at detecting and isolating enzymes with potential for polyester degradation such as polyethylene terephthalate (PET) are limited. In this work, we explored the metagenomic library of an oil-enriched soil sample from the “Los Humeros” geothermal field by means of in silico probes in search for enzymes potentially able to degrade polyesters. Using conserved motifs and activity-relevant sites of reported polyester hydrolases, we designed probes that allowed us to identify 6 potential polyester hydrolases in the metagenome. Three-dimensional structure prediction revealed a canonical α/β fold and a cap covering the active site of the enzymes. The catalytic triads were composed of Ser, His and Asp. Structural comparison, substrate binding site analysis and molecular docking suggested their potential as polyester hydrolases, particularly cutinases and PETases. An enzyme, REC98271, was cloned, expressed and characterized, showing thermophilic properties and preference for short-chain substrates. These findings contribute to our understanding of enzyme diversity in “Los Humeros” metagenome and their potential applications in biodegradation and recycling processes. Full article
(This article belongs to the Special Issue New Trends in Industrial Biocatalysis)
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15 pages, 3819 KiB  
Review
Advancements in Materials Science and Photocatalysts for Sustainable Development
by Dhanalakshmi Vadivel, Swetha Suryakumar, Claudio Casella, Andrea Speltini and Daniele Dondi
Catalysts 2024, 14(6), 378; https://doi.org/10.3390/catal14060378 - 14 Jun 2024
Cited by 2 | Viewed by 1158
Abstract
Materials science and catalysis advancements play a critical role in achieving sustainable development by managing environmental, energy, and resource challenges. Catalyst design advancements focus on enhancing selectivity to achieve sustainable chemical reactions, reducing energy consumption. Designing catalysts that are environmentally friendly and biodegradable [...] Read more.
Materials science and catalysis advancements play a critical role in achieving sustainable development by managing environmental, energy, and resource challenges. Catalyst design advancements focus on enhancing selectivity to achieve sustainable chemical reactions, reducing energy consumption. Designing catalysts that are environmentally friendly and biodegradable is increasingly gaining importance. This aligns with the principles of green chemistry and contributes to minimizing the environmental impact of catalytic processes. These advances, taken as a whole, lead to more sustainable and efficient processes in industries ranging from energy production to pollutant removal, fueling the advancement toward a more sustainable future. Photochemistry, that is, the activation of a stable compound (catalyst) into the highly reactive excited state, is of particular importance, since photons—especially when they come from solar light—are a green and renewable resource. This review article has provided the overall idea of the photocatalysts and materials under green chemistry perspective from the standpoint of the concept of sustainable development. Full article
(This article belongs to the Special Issue Photocatalysis and Renewable Materials, 2nd Edition)
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14 pages, 4572 KiB  
Article
Photocatalytic Degradation of Crystal Violet (CV) Dye over Metal Oxide (MOx) Catalysts
by Mohammed Sifat, Eugene Shin, Anthony Schevon, Hugo Ramos, Amol Pophali, Hye-Jung Jung, Gary Halada, Yizhi Meng, Nicholas Olynik, David J. Sprouster and Taejin Kim
Catalysts 2024, 14(6), 377; https://doi.org/10.3390/catal14060377 - 14 Jun 2024
Cited by 1 | Viewed by 1267
Abstract
Crystal violet (CV) is an organic chloride salt and a triphenylmethane dye commonly used in the textile processing industry, also being used as a disinfectant and a biomedical stain. Although CV is widely used, it is carcinogenic to humans and is retained by [...] Read more.
Crystal violet (CV) is an organic chloride salt and a triphenylmethane dye commonly used in the textile processing industry, also being used as a disinfectant and a biomedical stain. Although CV is widely used, it is carcinogenic to humans and is retained by industrial-produced effluent for an extended period. The different types of metal oxide (MOx) have impressive photocatalytic properties, allowing them to be utilized for pollutant degradation. The role of the photocatalyst is to facilitate oxidation and reduction processes by trapping light energy. In this study, we investigated different types of metal oxides, such as titanium dioxide (TiO2), zinc oxide (ZnO), zirconium dioxide (ZrO2), iron (III) oxide (Fe2O3), copper (II) oxide (CuO), copper (I) oxide (Cu2O), and niobium pentoxide (Nb2O5) for the CV decomposition reaction at ambient conditions. For characterization, BET and Raman spectroscopy were applied, providing findings showing that the surface area of the anatase TiO2 and ZnO were 5 m2/g and 12.1 m2/g, respectively. The activity tests over TiO2 and ZnO catalysts revealed that up to ~98% of the dye could be decomposed under UV irradiation in <2 h. The decomposition of CV is directly influenced by various factors, such as the types of MOx, the band gap–water splitting relationship, and the recombination rate of electron holes. Full article
(This article belongs to the Section Catalytic Materials)
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17 pages, 2480 KiB  
Article
Impact of Inorganic Anions on the Photodegradation of Herbicide Residues in Water by UV/Persulfate-Based Advanced Oxidation
by Gabriel Pérez-Lucas, Aitor Campillo and Simón Navarro
Catalysts 2024, 14(6), 376; https://doi.org/10.3390/catal14060376 - 13 Jun 2024
Viewed by 1138
Abstract
The removal of pesticides and other organic pollutants from water through advanced oxidation processes (AOPs) holds great promise. The main advantage of these technologies is that they remove, or at least reduce, pesticide levels by mineralization rather than transfer, as in conventional processes. [...] Read more.
The removal of pesticides and other organic pollutants from water through advanced oxidation processes (AOPs) holds great promise. The main advantage of these technologies is that they remove, or at least reduce, pesticide levels by mineralization rather than transfer, as in conventional processes. This study first evaluated the effectiveness of UV/S2O8= compared to heterogeneous photocatalysis using UV/TiO2 processes on the degradation of two commonly used herbicides (terbuthylazine and isoproturon) in aqueous solutions using a laboratory photoreactor. In addition, the effect of the UV wavelength on the degradation efficiency of both herbicides was investigated. Although the degradation rate was greater under UV(254)/S2O8= nm than under UV(365)/S2O8= nm, complete degradation of the herbicides (0.2 mg L−1) was achieved within 30 min under UV-366 nm using a Na2S2O8 dose of 250 mg L−1 in the absence of inorganic anions. To assess the impact of the water matrix, the individual and combined effects of sulfate (SO4=), bicarbonate (HCO3−), and chloride (Cl−) were evaluated. These can react with hydroxyl (HO•) and sulfate (SO4•−) radicals generated during AOPs to form new radicals with a lower redox potential. The results showed negligible effects of SO4=, while the combination of HCO3− and Cl− seemed to be the key to the decrease in herbicide removal efficiency found when working with complex matrices. Finally, the main intermediates detected during the photodegradation process are identified, and the likely pathways involving dealkylation, dechlorination, and hydroxylation are proposed and discussed. Full article
(This article belongs to the Special Issue Recent Advances in Photocatalytic Treatment of Pollutants in Water)
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23 pages, 10145 KiB  
Review
Morphology and Microstructural Optimization of Zeolite Crystals Utilizing Polymer Growth Modifiers for Enhanced Catalytic Application
by Junling Zhan, Chongyao Bi, Xiaohui Du, Tao Liu and Mingjun Jia
Catalysts 2024, 14(6), 375; https://doi.org/10.3390/catal14060375 - 12 Jun 2024
Viewed by 1025
Abstract
Rationally controlling the morphology and microstructure of the zeolite crystals could play a significant role in optimizing their physicochemical properties and catalytic performances for application in various zeolite-based heterogeneous catalysis processes. Among different controlling strategies, the utilization of zeolite growth modifiers (ZGMs), which [...] Read more.
Rationally controlling the morphology and microstructure of the zeolite crystals could play a significant role in optimizing their physicochemical properties and catalytic performances for application in various zeolite-based heterogeneous catalysis processes. Among different controlling strategies, the utilization of zeolite growth modifiers (ZGMs), which are molecules capable of altering the anisotropic rates of crystal growth, is becoming a promising approach to modulate the morphology and microstructural characteristics of zeolite crystals. In this mini-review, we attempt to provide an organized overview of the recent progress in the usage of several easily available polymer-based growth modifiers in the synthesis of some commonly used microporous zeolites and to reveal their roles in controlling the morphology and various physicochemical properties of zeolite crystals during hydrothermal synthesis processes. This review is expected to provide some guidance for deeply understanding the modulation mechanisms of polymer-based zeolite growth modifiers and for appropriately utilizing such a modulation strategy to achieve precise control of the morphology and microstructure of zeolite crystals that display optimal performance in the target catalytic reactions. Full article
(This article belongs to the Special Issue Surface Microstructure Design for Advanced Catalysts)
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20 pages, 7373 KiB  
Review
S-Scheme Heterojunction Photocatalysts for CO2 Reduction
by Mingli Li, He Cui, Yi Zhao, Shunli Li, Jiabo Wang, Kai Ge and Yongfang Yang
Catalysts 2024, 14(6), 374; https://doi.org/10.3390/catal14060374 - 12 Jun 2024
Cited by 2 | Viewed by 1224
Abstract
Photocatalytic technology, which is regarded as a green route to transform solar energy into chemical fuels, plays an important role in the fields of energy and environmental protection. An emerging S-scheme heterojunction with the tightly coupled interface, whose photocatalytic efficiency exceeds those of [...] Read more.
Photocatalytic technology, which is regarded as a green route to transform solar energy into chemical fuels, plays an important role in the fields of energy and environmental protection. An emerging S-scheme heterojunction with the tightly coupled interface, whose photocatalytic efficiency exceeds those of conventional type II and Z-scheme photocatalysts, has received much attention due to its rapid charge carrier separation and strong redox capacity. This review provides a systematic description of S-scheme heterojunction in the photocatalysis, including its development, reaction mechanisms, preparation, and characterization methods. In addition, S-scheme photocatalysts for CO2 reduction are described in detail by categorizing them as 0D/1D, 0D/2D, 0D/3D, 2D/2D, and 2D/3D. Finally, some defects of S-scheme heterojunctions are pointed out, and the future development of S-scheme heterojunctions is proposed. Full article
(This article belongs to the Special Issue Novel Nano-Heterojunctions with Enhanced Catalytic Activity)
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42 pages, 11729 KiB  
Review
Recent Advances of PtCu Alloy in Electrocatalysis: Innovations and Applications
by Ziyang Shen, Jinyao Tang and Xiaochen Shen
Catalysts 2024, 14(6), 373; https://doi.org/10.3390/catal14060373 - 11 Jun 2024
Cited by 1 | Viewed by 1773
Abstract
Developing highly active and durable platinum-based catalysts is crucial for electrochemical renewable energy conversion technologies but the limited supply and high cost of platinum have hindered their widespread implementation. The incorporation of non-noble metals, particularly copper, into Pt catalysts has been demonstrated as [...] Read more.
Developing highly active and durable platinum-based catalysts is crucial for electrochemical renewable energy conversion technologies but the limited supply and high cost of platinum have hindered their widespread implementation. The incorporation of non-noble metals, particularly copper, into Pt catalysts has been demonstrated as an effective solution to reduce Pt consumption while further promoting their performance, making them promising for various electrocatalytic reactions. This review summarizes the latest advances in PtCu-based alloy catalysts over the past several years from both synthetic and applied perspectives. In the synthesis section, the selection of support and reagents, synthesis routes, as well as post-treatment methods at high temperatures are reviewed. The application section focuses not only on newly proposed electrochemical reactions such as nitrogen-related reactions and O2 reduction but also extends to device-level applications. The discussion in this review aims to provide further insights and guidance for the development of PtCu electrocatalysts for practical applications. Full article
(This article belongs to the Special Issue Electrocatalysis/Photocatalysis for CO2 Conversion, H2 Production, and Pollutant Removal, 2nd Edition)
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13 pages, 7258 KiB  
Article
Facile Abatement of Oxygenated Volatile Organic Compounds via Hydrogen Co-Combustion over Pd/Al2O3 Catalyst as Onsite Heating Source
by Lutf Ullah, Sehrish Munsif, Long Cao, Jing-Cai Zhang and Wei-Zhen Li
Catalysts 2024, 14(6), 372; https://doi.org/10.3390/catal14060372 - 10 Jun 2024
Cited by 2 | Viewed by 1058
Abstract
Catalytic combustion of volatile organic compounds (VOCs) usually requires external energy input to hold the desired reaction temperature via electric heating. This work presents an example of internal onsite heating of the catalytic active sites via hydrogen catalytic combustion with air over a [...] Read more.
Catalytic combustion of volatile organic compounds (VOCs) usually requires external energy input to hold the desired reaction temperature via electric heating. This work presents an example of internal onsite heating of the catalytic active sites via hydrogen catalytic combustion with air over a conventional Pd/Al2O3 catalyst. Hydrogen combustion was ignited by the catalyst at room temperature without electric heating, and thus the temperatures were readily varied with the concentrations of H2. Representative oxygenated VOCs such as methanol, formaldehyde and formic acid can be completely oxidized into CO2 and water by co-feeding with H2 below its low explosion limit of 4% using Pd/Al2O3 as shared catalyst. The catalytic performance apparently is not sensitive to the sizes of Pd nanoparticles in fresh and spent states, as revealed by XRD and STEM. This provides an option for using renewable green hydrogen to eliminate VOC pollutants in an energy-efficient way. Full article
(This article belongs to the Section Industrial Catalysis)
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24 pages, 2031 KiB  
Review
Strategies to Prepare Chitin and Chitosan-Based Bioactive Structures Aided by Deep Eutectic Solvents: A Review
by D. Alonzo Durante-Salmerón, Isabel Fraile-Gutiérrez, Rubén Gil-Gonzalo, Niuris Acosta, Inmaculada Aranaz and Andrés R. Alcántara
Catalysts 2024, 14(6), 371; https://doi.org/10.3390/catal14060371 - 10 Jun 2024
Viewed by 2207
Abstract
Chitin and chitosan, abundant biopolymers derived from the shells of crustaceans and the cell walls of fungi, have garnered considerable attention in pharmaceutical circles due to their biocompatibility, biodegradability, and versatile properties. Deep eutectic solvents (DESs), emerging green solvents composed of eutectic mixtures [...] Read more.
Chitin and chitosan, abundant biopolymers derived from the shells of crustaceans and the cell walls of fungi, have garnered considerable attention in pharmaceutical circles due to their biocompatibility, biodegradability, and versatile properties. Deep eutectic solvents (DESs), emerging green solvents composed of eutectic mixtures of hydrogen bond acceptors and donors, offer promising avenues for enhancing the solubility and functionality of chitin and chitosan in pharmaceutical formulations. This review delves into the potential of utilizing DESs as solvents for chitin and chitosan, highlighting their efficiency in dissolving these polymers, which facilitates the production of novel drug delivery systems, wound dressings, tissue engineering scaffolds, and antimicrobial agents. The distinctive physicochemical properties of DESs, including low toxicity, low volatility, and adaptable solvation power, enable the customization of chitin and chitosan-based materials to meet specific pharmaceutical requirements. Moreover, the environmentally friendly nature of DESs aligns with the growing demand for sustainable and eco-friendly processes in pharmaceutical manufacturing. This revision underscores recent advances illustrating the promising role of DESs in evolving the pharmaceutical applications of chitin and chitosan, laying the groundwork for the development of innovative drug delivery systems and biomedical materials with enhanced efficacy and safety profiles. Full article
(This article belongs to the Special Issue Catalytic Procedures for the Synthesis of Pharmaceutical Active Compounds in Deep Eutectic Solvents)
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11 pages, 1842 KiB  
Article
CO2 Oxidative Dehydrogenation of Propane to Olefin over Cr-M (M = Zr, La, Fe) Based Zeolite Catalyst
by Mingqiao Xing, Ning Liu, Chengna Dai and Biaohua Chen
Catalysts 2024, 14(6), 370; https://doi.org/10.3390/catal14060370 - 7 Jun 2024
Cited by 1 | Viewed by 1170
Abstract
CO2 oxidative dehydrogenation of propane (CO2-ODHP), being not only favorable for olefin production but also beneficial for CO2 emission control, has recently attracted great attention. Here, a series of single metal (Cr) and bimetal (Zr, La, Fe) modified ZSM-5 [...] Read more.
CO2 oxidative dehydrogenation of propane (CO2-ODHP), being not only favorable for olefin production but also beneficial for CO2 emission control, has recently attracted great attention. Here, a series of single metal (Cr) and bimetal (Zr, La, Fe) modified ZSM-5 zeolites were prepared via an impregnation method. It was found that the bimetal modified ZSM-5 possessed much higher C3H8 and CO2 conversion than that of monometallic modified Cr3%-ZSM-5 (Cr3%-Z5), especially for Cr3%Zr2%-ZSM-5 (Cr3%Zr2%-Z5), which displayed the highest activity (65.4%) and olefin yield (1.65 × 103 μmol·gcat−1 h−1). Various characterizations were performed, including XRD, N2 adsorption-desorption, H2-TPR, Raman, XPS, HAAD-STEM, and TEM. It was revealed that Zr not only favored an improvement in the redox ability of Cr, but also contributed to the surface dispersion of loaded Cr species, constituting two major reasons explaining the superior activity of Cr3%Zr2%-Z5. To further improve CO2-ODHP catalytic behavior, a series of Cr3%-ZSM-5@SBA-15-n composite zeolite catalysts with diverse (ZSM-5/SBA-15) mass ratios were prepared (Cr3%-ZS-n, n = 0.5, 2, 6, 16), which screened out an optimum mass ratio of six. Based on this, the Cr3%Zr2%-ZS-6 compound was further prepared, and it eventually achieved even higher CO2-ODHP activity (76.9%) and olefin yield (1.72 × 103 μmol·gcat−1 h−1). Finally, the CO2-ODHP reaction mechanism was further investigated using in situ FTIR, and it was found that the reaction followed the Mars–van Krevelen mechanism, wherein CO2 participated in the reaction through generation of polydentate carbonates. The Cr6+ constituted as the active site, which was reduced to Cr3+ after the dihydrogen reaction, and was then further oxidized into Cr6+ by CO2, forming polydentate carbonates, and thus cycling the reactive species Cr6+. Additionally, assisted by a Brönsted acid site (favoring breaking of the C-C bond), C2H4 and CH4 were produced. Full article
(This article belongs to the Special Issue Zeolites and Zeolite-Based Catalysis)
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14 pages, 10965 KiB  
Article
Green Synthesis of Manganese-Cobalt Oxyhydroxide Nanocomposite as Electrocatalyst for Enhanced Oxygen Evolution Reaction in Alkaline Medium
by Rajeh Alotaibi, Mabrook S. Amer, Prabhakarn Arunachalam and Saad G. Alshammari
Catalysts 2024, 14(6), 369; https://doi.org/10.3390/catal14060369 - 6 Jun 2024
Cited by 1 | Viewed by 1270
Abstract
Using green synthetic methods, a manganese-cobalt oxyhydroxide (MnCo-OOH) nanocomposite for electrocatalysis was prepared. Electrocatalysts were examined using powder X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy (FESEM). In an alkaline medium, cyclic voltammetry and chronoamperometric analysis were [...] Read more.
Using green synthetic methods, a manganese-cobalt oxyhydroxide (MnCo-OOH) nanocomposite for electrocatalysis was prepared. Electrocatalysts were examined using powder X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy (FESEM). In an alkaline medium, cyclic voltammetry and chronoamperometric analysis were applied to assess the electrocatalytic features of the MnCo-OOH nanocomposite. A strong correlation existed between MnCo-OOH’s morphology, crystallinity, and electrochemical activity. Upon examining the electrochemical characteristics, the as-deposited MnCo-OOH catalyst demonstrated a significantly lower overpotential, achieving 75 mA·cm−2 OER current density at 370 mV, four times larger than 19.7 mA·cm−2 for CoOOH catalysts, signifying that the MnCo-OOH catalyst exhibits a higher electrocatalytic OER features. In addition, the MnCo-OOH nanocomposite demonstrated a high current density of 30 and 65 mA·cm−2 at 1.55 and 1.60 VRHE for 12 h in 1.0 M KOH aqueous electrolyte. As a result of this study, it was determined that the fabricated MnCo-OOH nanocomposite would be an appropriate electrocatalyst in water electrolysis. Full article
(This article belongs to the Section Electrocatalysis)
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28 pages, 6021 KiB  
Review
Recent Advances in Vanadium-Based Electrocatalysts for Hydrogen and Oxygen Evolution Reactions: A Review
by Haoyu Li, Juan Wu, Mengyao Li and Yude Wang
Catalysts 2024, 14(6), 368; https://doi.org/10.3390/catal14060368 - 5 Jun 2024
Viewed by 1770
Abstract
With the intensification of global resource shortages and the environmental crisis, hydrogen energy has garnered significant attention as a renewable and clean energy source. Water splitting is considered the most promising method of hydrogen production due to its non-polluting nature and high hydrogen [...] Read more.
With the intensification of global resource shortages and the environmental crisis, hydrogen energy has garnered significant attention as a renewable and clean energy source. Water splitting is considered the most promising method of hydrogen production due to its non-polluting nature and high hydrogen concentration. However, the slow kinetics of the two key reactions, the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER), have greatly limited the development of related technologies. Meanwhile, the scarcity and high cost of precious metal catalysts represented by Pt and Ir/RuO2 limit their large-scale commercial application. Thus, it is essential to develop catalysts based on Earth’s transition metals that have abundant reserves. Vanadium (V) is an early transition metal with a distinct electronic structure from late transition metals such as Fe, Co, and Ni, which has been emphasized and studied by researchers. Numerous vanadium-based electrocatalysts have been developed for the HER and OER. In this review, the mechanisms of the HER and OER are described. Then, the compositions, properties, and modification strategies of various vanadium-based electrocatalysts are summarized, which include vanadium-based oxides, hydroxides, dichalcogenides, phosphides, nitrides, carbides, and vanadate. Finally, potential challenges and future perspectives are presented based on the current status of V-based electrocatalysts for water splitting. Full article
(This article belongs to the Special Issue Nanostructures for Catalysis: From Synthesis and Characterization to Applications)
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12 pages, 17335 KiB  
Article
Acetylacetone Boosts the Photocatalytic Activity of Metal–Organic Frameworks by Tunable Modification
by Kunrui Wei, Jianghua Yang, Shuangshuang Wei, Hongcen Zheng and Shujuan Zhang
Catalysts 2024, 14(6), 367; https://doi.org/10.3390/catal14060367 - 5 Jun 2024
Viewed by 952
Abstract
Typical metal–organic frameworks (MOFs) usually suffer from a limited visible light-trapping ability and easy recombination of charge carriers, hindering their photocatalytic applications. Acetylacetone (AA), leveraging its exceptional coordination capabilities, serves as a versatile and effective modifier for enhancing the photocatalytic activity of MOFs [...] Read more.
Typical metal–organic frameworks (MOFs) usually suffer from a limited visible light-trapping ability and easy recombination of charge carriers, hindering their photocatalytic applications. Acetylacetone (AA), leveraging its exceptional coordination capabilities, serves as a versatile and effective modifier for enhancing the photocatalytic activity of MOFs via a post-synthesis approach. The synthesis of diketone-anchored MOFs with AA can be achieved by first diazotizing the amino groups on the ligands of MOFs, followed by a condensation reaction between AA and the resulting azide. Gradient AA loadings ranging from 17% to 98% were obtained, showcasing the tunability of this approach. Interestingly, a sub-stoichiometric effect was exhibited between the AA loading and the visible photocatalytic performance of the modified photocatalyst. The singlet oxygen yields of MIL-125-AA-37% and MIL-125-AA-54% were about 1.3 times that of MIL-125-AA-17% and 3.0 times that of MIL-125-AA-98%. The improved photocatalytic activity could be attributed to the fact that the AA modification altered the electron density of the Ti metal center, leading to the creation of a significant amount of oxygen defects. This alteration resulted in a reduction in the recombination of charge carriers and thus a better charge separation. In short, AA modification provides a new strategy to maximize the visible photocatalytic performance of MOFs. Full article
(This article belongs to the Special Issue Exclusive Papers in Green Photocatalysis from China)
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27 pages, 12141 KiB  
Review
TiO2-Based Catalysts with Various Structures for Photocatalytic Application: A Review
by Cheng Song, Lanqing Xiao, Yan Chen, Fan Yang, Huiying Meng, Wanying Zhang, Yifan Zhang and Yang Wu
Catalysts 2024, 14(6), 366; https://doi.org/10.3390/catal14060366 - 4 Jun 2024
Cited by 29 | Viewed by 2208
Abstract
TiO2-based catalysts with various surface heterostructures (0D, 1D, 2D, and 3D) have been widely researched owing to their cost-effectiveness, high stability, and environmentally friendly nature, and can be used for many applications in various fields, including hydrogen production and pollutant degradation. [...] Read more.
TiO2-based catalysts with various surface heterostructures (0D, 1D, 2D, and 3D) have been widely researched owing to their cost-effectiveness, high stability, and environmentally friendly nature, and can be used for many applications in various fields, including hydrogen production and pollutant degradation. However, there are also many existing problems limiting their practical application, such as their large band gap and rapid electron–hole recombination rate. Owing to the abundance of recent achievements in materials science, we will summarize the recent structural engineering strategies which provide favorable photocatalytic activity enhancements, such as enhanced visible light absorption, stability, an increased charge–carrier separation rate and improved specific surface area. Among the various structural engineering methods in this review, we will introduce TiO2-based materials with different dimensional structures. Meanwhile, we also discuss recent achievements in synthesis methods and application of TiO2-based catalysts in various fields. We aim to display a comprehensive overview which can be a guide for the development of a new generation of TiO2-based catalysts according to their structural design for enhanced solar energy conversion. Full article
(This article belongs to the Section Catalytic Materials)
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16 pages, 4774 KiB  
Article
Pt3Mn/SiO2 + ZSM-5 Bifunctional Catalyst for Ethane Dehydroaromatization
by Shan Jiang, Che-Wei Chang, William A. Swann, Christina W. Li and Jeffrey T. Miller
Catalysts 2024, 14(6), 365; https://doi.org/10.3390/catal14060365 - 4 Jun 2024
Cited by 1 | Viewed by 1032
Abstract
Ethane dehydroaromatization (EDA) is a potentially attractive process for converting ethane to valuable aromatics such as benzene, toluene, and xylene (BTX). In this study, a Pt3Mn/SiO2 + ZSM-5 bifunctional catalyst was used to investigate the effect of dehydrogenation and the [...] Read more.
Ethane dehydroaromatization (EDA) is a potentially attractive process for converting ethane to valuable aromatics such as benzene, toluene, and xylene (BTX). In this study, a Pt3Mn/SiO2 + ZSM-5 bifunctional catalyst was used to investigate the effect of dehydrogenation and the Brønsted acid catalyst ratio, hydrogen partial pressure, and reaction temperature on the product distributions for EDA. Pt3Mn/SiO2 + ZSM-5 with a 1/1 weight ratio showed the highest ethane conversion rate and BTX formation rate. Ethylene is initially formed by dehydrogenation by the Pt3Mn catalyst, which undergoes secondary reactions on ZSM-5, forming C3+ reaction intermediates. The latter form final products of CH4 and BTX. At conversions from 15 to 30%, the BTX selectivities are 82–90%. For all bifunctional catalysts, the ethane conversion significantly exceeds the ethane–ethylene equilibrium conversion due to reaction to secondary products. Low H2 partial pressures did not significantly alter the product selectivity or conversion. However, higher H2 partial pressures resulted in increased methane and decreased BTX selectivity. The excess hydrogen saturated the olefin intermediates to form alkanes, which produced methane by monomolecular cracking on ZSM-5. With an increasing reaction temperature from 550 °C to 650 °C, the benzene selectivity increased, while the highest BTX selectivity was obtained at 600 to 650 °C. Full article
(This article belongs to the Special Issue Research Advances in Zeolites and Zeolite-Based Catalysts)
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15 pages, 3921 KiB  
Article
Modification of NiSe2 Nanoparticles by ZIF-8-Derived NC for Boosting H2O2 Production from Electrochemical Oxygen Reduction in Acidic Media
by Qiaoting Cheng, Hu Ding, Lang Chen, Jiatong Dong, Hao Yu, Shen Yan and Hua Wang
Catalysts 2024, 14(6), 364; https://doi.org/10.3390/catal14060364 - 3 Jun 2024
Cited by 1 | Viewed by 940
Abstract
The two-electron oxygen reduction reaction (2e− ORR) has emerged as an attractive alternative for H2O2 production. Developing efficient earth-abundant transition metal electrocatalysts and reaction mechanism exploration for H2O2 production are important but remain challenging. Herein, a [...] Read more.
The two-electron oxygen reduction reaction (2e− ORR) has emerged as an attractive alternative for H2O2 production. Developing efficient earth-abundant transition metal electrocatalysts and reaction mechanism exploration for H2O2 production are important but remain challenging. Herein, a nitrogen-doped carbon-coated NiSe2 (NiSe2@NC) electrocatalyst was prepared by successive annealing treatment. Benefiting from the synergistic effect between the NiSe2 nanoparticles and NC, the 2e− ORR activity, selectivity, and stability of NiSe2@NC in 0.1 M HClO4 was greatly enhanced, with the yield of H2O2 being 4.4 times that of the bare NiSe2 nanoparticles. The in situ Raman spectra and density functional theory (DFT) calculation revealed that the presence of NC was beneficial for regulating the electronic state of NiSe2 and optimizing the adsorption free energy of *OOH, which could enhance the adsorption of O2, stabilize the O-O bond, and boost the production of H2O2. This work provides an effective strategy to improve the performance of the transition metal chalcogenide for 2e− ORR to H2O2. Full article
(This article belongs to the Special Issue Electrocatalysis for Hydrogen/Oxygen Evolution Reactions)
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