Pub Date : 2025-03-01DOI: 10.1016/j.mtcata.2025.100092
Chen Chen
The construction of C–N bond and synthesis of N-containing compounds directly from N2 is an extremely attractive subject. The co-electrolysis system coupled with renewable electricity provides one of the potential options for the green and controllable C–N bond construction under ambient conditions, bypassing the intermediate process of ammonia synthesis. In this review, we have summarized the recent progress in ambient urea synthesis via electrocatalytic C–N coupling from CO2 and nitrogenous species. The reaction mechanisms studies of N2 and CO2 coupling has been mainly highlighted, and the coupling enhancement strategies are emphasized for the coupling of nitrate and CO2, including intermediate adsorption regulation, functional synergy, site reconstitution and local-environment construction. Moreover, promising directions and remaining challenges are outlined, encompassing the mechanism study combining theory and experiment, reactant source and product application, optimization of urea synthesis evaluation system and the development of devices aiming to coupling system. This review aims to guide further advancements in electrocatalytic C–N coupling, facilitating the efficient and sustainable synthesis of urea for a broad spectrum of applications.
{"title":"Ambient urea synthesis via electrocatalytic C–N coupling","authors":"Chen Chen","doi":"10.1016/j.mtcata.2025.100092","DOIUrl":"10.1016/j.mtcata.2025.100092","url":null,"abstract":"<div><div>The construction of C–N bond and synthesis of N-containing compounds directly from N<sub>2</sub> is an extremely attractive subject. The co-electrolysis system coupled with renewable electricity provides one of the potential options for the green and controllable C–N bond construction under ambient conditions, bypassing the intermediate process of ammonia synthesis. In this review, we have summarized the recent progress in ambient urea synthesis via electrocatalytic C–N coupling from CO<sub>2</sub> and nitrogenous species. The reaction mechanisms studies of N<sub>2</sub> and CO<sub>2</sub> coupling has been mainly highlighted, and the coupling enhancement strategies are emphasized for the coupling of nitrate and CO<sub>2</sub>, including intermediate adsorption regulation, functional synergy, site reconstitution and local-environment construction. Moreover, promising directions and remaining challenges are outlined, encompassing the mechanism study combining theory and experiment, reactant source and product application, optimization of urea synthesis evaluation system and the development of devices aiming to coupling system. This review aims to guide further advancements in electrocatalytic C–N coupling, facilitating the efficient and sustainable synthesis of urea for a broad spectrum of applications.</div></div>","PeriodicalId":100892,"journal":{"name":"Materials Today Catalysis","volume":"8 ","pages":"Article 100092"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-01DOI: 10.1016/j.mtcata.2025.100094
Mingxing Nie , Fengyi Liu , Zijian Wang , Wei Gan , Jie Yu , Bin Wu , Qunhui Yuan
Exploring highly active catalysts with high Pt utilization rates is still challenging for direct ethanol fuel cells (DFECs). Herein, we report a facile synthesis of three-dimensional (3D) vertical graphene (VG) supported PtCo alloy nanoparticles (PtCo/VG) as catalysts for ethanol oxidation reactions (EOR). The 3D interconnected open network and exposed edges of VG nanosheets provide an ideal support for hindering the aggregation of PtCo nanoparticles and thus the PtCo nanoparticles achieve an ultrasmall size of 3.7 nm and a high dispersion on VG supports. PtCo/VG displays a superb mass activity (4.33 A mg−1) and specific activity (5.14 mA cm−2) toward EOR, which are 5.6 and 3.5 times to those of commercial Pt/C, respectively. The catalytic activity of PtCo/VG also surpasses its counterparts of carbon fibers supported PtCo (PtCo/CNFs) and XC-72 supported PtCo (PtCo/XC-72), and behaves amazingly among many reported Pt-based catalysts. Density functional theory (DFT) calculations demonstrate that the introduction of VG supports lowered the Pt d-band center, weakened the CO adsorption and strengthened the OH adsorption on catalytic sites of PtCo/VG. This work may pave the way for fabricating highly carbon-based efficient bifunctional electrocatalysts with high platinum utilization for fuel cells.
对于直接乙醇燃料电池（DFECs）来说，探索具有高Pt利用率的高活性催化剂仍然是一个挑战。在此，我们报道了三维（3D）垂直石墨烯（VG）负载的PtCo合金纳米颗粒（PtCo/VG）作为乙醇氧化反应（EOR）催化剂的简单合成。三维互联的开放网络和VG纳米片的暴露边缘为阻碍PtCo纳米颗粒的聚集提供了理想的支持，因此PtCo纳米颗粒实现了3.7 nm的超小尺寸和在VG载体上的高分散。PtCo/VG对EOR的质量活性（4.33 a mg−1）和比活性（5.14 mA cm−2）分别是商业Pt/C的5.6倍和3.5倍。PtCo/VG的催化活性也超过了碳纤维负载的PtCo （PtCo/CNFs）和XC-72负载的PtCo (PtCo/XC-72)，并且在许多已报道的pt基催化剂中表现出色。密度泛函理论（DFT）计算表明，VG载体的引入降低了PtCo/VG催化位点的Pt d波段中心，减弱了CO的吸附，增强了OH的吸附。该研究为制备高铂利用率的高碳基高效双功能电催化剂铺平了道路。
{"title":"Facile one-pot surfactant-free synthesis of 3D vertical graphene anchored ultrafine PtCo nanoparticles for ethanol oxidation","authors":"Mingxing Nie , Fengyi Liu , Zijian Wang , Wei Gan , Jie Yu , Bin Wu , Qunhui Yuan","doi":"10.1016/j.mtcata.2025.100094","DOIUrl":"10.1016/j.mtcata.2025.100094","url":null,"abstract":"<div><div>Exploring highly active catalysts with high Pt utilization rates is still challenging for direct ethanol fuel cells (DFECs). Herein, we report a facile synthesis of three-dimensional (3D) vertical graphene (VG) supported PtCo alloy nanoparticles (PtCo/VG) as catalysts for ethanol oxidation reactions (EOR). The 3D interconnected open network and exposed edges of VG nanosheets provide an ideal support for hindering the aggregation of PtCo nanoparticles and thus the PtCo nanoparticles achieve an ultrasmall size of 3.7 nm and a high dispersion on VG supports. PtCo/VG displays a superb mass activity (4.33 A mg<sup>−1</sup>) and specific activity (5.14 mA cm<sup>−2</sup>) toward EOR, which are 5.6 and 3.5 times to those of commercial Pt/C, respectively. The catalytic activity of PtCo/VG also surpasses its counterparts of carbon fibers supported PtCo (PtCo/CNFs) and XC-72 supported PtCo (PtCo/XC-72), and behaves amazingly among many reported Pt-based catalysts. Density functional theory (DFT) calculations demonstrate that the introduction of VG supports lowered the Pt d-band center, weakened the CO adsorption and strengthened the OH adsorption on catalytic sites of PtCo/VG. This work may pave the way for fabricating highly carbon-based efficient bifunctional electrocatalysts with high platinum utilization for fuel cells.</div></div>","PeriodicalId":100892,"journal":{"name":"Materials Today Catalysis","volume":"8 ","pages":"Article 100094"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrogen peroxide (H2O2) is a valuable chemical, and its eco-friendly electrochemical production has gained attention to obtain pH-neutral aqueous solutions without impurities. However, achieving H2O2 faradaic efficiencies (FEs) above 30 % has been a challenge with conventional proton exchange membrane (PEM) electrolyzers. To enhance H2O2 FE, efficient collection of H2O2 from the catalyst surface using liquid water is necessary, but oxygen diffusion becomes a limiting factor in aqueous-immersed systems. To overcome this, we designed a zero-gap electrolyzer, supplying oxygen gas from the anode side through the membrane to the cathode. A gas flow-through porous PEM was developed by embedding an acidic ionomer into a membrane filter, enabling the crossover oxygen supply to the cathode flooded with water. This porous PEM design facilitated the formation of a three-phase interface at the catalyst, where high-concentration oxygen gas and liquid water interact closely, achieving 79 % H2O2 FE at 5 mA cm−2. Continuous synthesis of pure H2O2 solution exceeding 5500 mg L−1 (0.55 wt%) was sustained for over 50 hours.
{"title":"Electrocatalytic synthesis of pure H2O2 from crossover oxygen through a porous proton exchange membrane","authors":"Kazuma Enomoto, Takuya Okazaki, Kosuke Beppu, Fumiaki Amano","doi":"10.1016/j.mtcata.2025.100088","DOIUrl":"10.1016/j.mtcata.2025.100088","url":null,"abstract":"<div><div>Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) is a valuable chemical, and its eco-friendly electrochemical production has gained attention to obtain pH-neutral aqueous solutions without impurities. However, achieving H<sub>2</sub>O<sub>2</sub> faradaic efficiencies (FEs) above 30 % has been a challenge with conventional proton exchange membrane (PEM) electrolyzers. To enhance H<sub>2</sub>O<sub>2</sub> FE, efficient collection of H<sub>2</sub>O<sub>2</sub> from the catalyst surface using liquid water is necessary, but oxygen diffusion becomes a limiting factor in aqueous-immersed systems. To overcome this, we designed a zero-gap electrolyzer, supplying oxygen gas from the anode side through the membrane to the cathode. A gas flow-through porous PEM was developed by embedding an acidic ionomer into a membrane filter, enabling the crossover oxygen supply to the cathode flooded with water. This porous PEM design facilitated the formation of a three-phase interface at the catalyst, where high-concentration oxygen gas and liquid water interact closely, achieving 79 % H<sub>2</sub>O<sub>2</sub> FE at 5 mA cm<sup>−2</sup>. Continuous synthesis of pure H<sub>2</sub>O<sub>2</sub> solution exceeding 5500 mg L<sup>−1</sup> (0.55 wt%) was sustained for over 50 hours.</div></div>","PeriodicalId":100892,"journal":{"name":"Materials Today Catalysis","volume":"8 ","pages":"Article 100088"},"PeriodicalIF":0.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-10DOI: 10.1016/j.mtcata.2025.100091
Ting Wai Lau , Qiong Lei , Jun Yin
The design of highly efficient hydrogen evolution reaction (HER) catalysts is a critical challenge in advancing electrochemical water splitting for renewable energy applications. Topological semimetals have recently emerged as promising candidates for HER catalysis; however, the relationship between their topological surface properties and catalytic performance remains poorly understood. Herein, we employ density functional theory (DFT) calculations to investigate the impact of facets on the HER activity of topological TaAs semimetal family (TaAs, NbP, NbAs, and TaP). Our results reveal that topological surface states persist across various facets, and facets with lower coordination numbers exhibit greater stability. Four key theoretical descriptors—Gibbs free energy changes, surface energy, energy barriers for water dissociation, and water adsorption energy—are assessed to provide a comprehensive evaluation of HER activity. For all four compounds, (111) and metal-rich (001) facets exhibit optimal energy values across these metrics, outperforming the benchmark Pt (111). The number of Fermi arcs is found to have a minimal influence on HER activity. Changes in the projected density of states (PDOS) of surface atoms strongly correlate with ΔGH*, serving as a more effective indicator of HER activity. These findings highlight the importance of a holistic evaluation framework that extends beyond Gibbs free energy changes alone, incorporating multiple factors to identify high-performance catalysts. This work provides new insights into the design principles for topological catalysts in HER and offers valuable guidance for developing next generation of electrocatalysts.
{"title":"Facet engineering of Weyl semimetals for efficient hydrogen evolution reaction","authors":"Ting Wai Lau , Qiong Lei , Jun Yin","doi":"10.1016/j.mtcata.2025.100091","DOIUrl":"10.1016/j.mtcata.2025.100091","url":null,"abstract":"<div><div>The design of highly efficient hydrogen evolution reaction (HER) catalysts is a critical challenge in advancing electrochemical water splitting for renewable energy applications. Topological semimetals have recently emerged as promising candidates for HER catalysis; however, the relationship between their topological surface properties and catalytic performance remains poorly understood. Herein, we employ density functional theory (DFT) calculations to investigate the impact of facets on the HER activity of topological TaAs semimetal family (TaAs, NbP, NbAs, and TaP). Our results reveal that topological surface states persist across various facets, and facets with lower coordination numbers exhibit greater stability. Four key theoretical descriptors—Gibbs free energy changes, surface energy, energy barriers for water dissociation, and water adsorption energy—are assessed to provide a comprehensive evaluation of HER activity. For all four compounds, (111) and metal-rich (001) facets exhibit optimal energy values across these metrics, outperforming the benchmark Pt (111). The number of Fermi arcs is found to have a minimal influence on HER activity. Changes in the projected density of states (PDOS) of surface atoms strongly correlate with Δ<em>G</em><sub>H*</sub>, serving as a more effective indicator of HER activity. These findings highlight the importance of a holistic evaluation framework that extends beyond Gibbs free energy changes alone, incorporating multiple factors to identify high-performance catalysts. This work provides new insights into the design principles for topological catalysts in HER and offers valuable guidance for developing next generation of electrocatalysts.</div></div>","PeriodicalId":100892,"journal":{"name":"Materials Today Catalysis","volume":"8 ","pages":"Article 100091"},"PeriodicalIF":0.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-07DOI: 10.1016/j.mtcata.2025.100090
Kang Huang , Zhixiu Lu , Shilong Dai , Chunyu Cui , Nam Dong Kim , Huilong Fei
Cycling Li-O2 batteries (LOBs) via LiOH is promising for developing practically viable batteries, while promoting the formation and decomposition of LiOH remains a challenge. Cobalt single atom catalysts (Co-SACs) have been exploited to mediate the direct 4e− oxygen reduction reaction for generating LiOH discharge products, but their inferior oxygen evolution activity renders the battery low energy efficiency and poor cycling life. Herein, we for the first time introduce LiBr redox mediator (RM) into the Co-SACs-catalyzed LOB system to facilitate the decomposition of LiOH. In the discharge process, the catalysis of Co-SAC is unaffected with the presence of LiBr. During charging, Br3− is identified as the oxidizer to decompose LiOH at an appropriate potential (3.6 V). Significantly, the soluble Br− is recyclable in the system as the BrO− intermediate could shuttle to the anode and react with Li metal to regenerate Br− so that the generation of LiBrO3 deposit is circumvented. Consequently, the fabricated LOB demonstrates fewer side reactions, stable energy efficiency (drop rate of 0.10 % per cycle) and long cycle life (300 cycles at 1000 mA/g) under the ambient atmosphere.
{"title":"Coupling cobalt single-atom catalyst with recyclable LiBr redox mediator enables stable LiOH-based Li-O2 batteries","authors":"Kang Huang , Zhixiu Lu , Shilong Dai , Chunyu Cui , Nam Dong Kim , Huilong Fei","doi":"10.1016/j.mtcata.2025.100090","DOIUrl":"10.1016/j.mtcata.2025.100090","url":null,"abstract":"<div><div>Cycling Li-O<sub>2</sub> batteries (LOBs) via LiOH is promising for developing practically viable batteries, while promoting the formation and decomposition of LiOH remains a challenge. Cobalt single atom catalysts (Co-SACs) have been exploited to mediate the direct 4e<sup>−</sup> oxygen reduction reaction for generating LiOH discharge products, but their inferior oxygen evolution activity renders the battery low energy efficiency and poor cycling life. Herein, we for the first time introduce LiBr redox mediator (RM) into the Co-SACs-catalyzed LOB system to facilitate the decomposition of LiOH. In the discharge process, the catalysis of Co-SAC is unaffected with the presence of LiBr. During charging, Br<sub>3</sub><sup>−</sup> is identified as the oxidizer to decompose LiOH at an appropriate potential (3.6 V). Significantly, the soluble Br<sup>−</sup> is recyclable in the system as the BrO<sup>−</sup> intermediate could shuttle to the anode and react with Li metal to regenerate Br<sup>−</sup> so that the generation of LiBrO<sub>3</sub> deposit is circumvented. Consequently, the fabricated LOB demonstrates fewer side reactions, stable energy efficiency (drop rate of 0.10 % per cycle) and long cycle life (300 cycles at 1000 mA/g) under the ambient atmosphere.</div></div>","PeriodicalId":100892,"journal":{"name":"Materials Today Catalysis","volume":"8 ","pages":"Article 100090"},"PeriodicalIF":0.0,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-06DOI: 10.1016/j.mtcata.2025.100089
Dazhi Yao , Chun Liu , Yanzhao Zhang , Shuhao Wang , Yan Nie , Man Qiao , Dongdong Zhu
Direct seawater electrolysis (DSE) has emerged as a compelling route to sustainable hydrogen production, leveraging the vast global reserves of seawater. However, the inherently complex composition of seawater—laden with halide ions, multivalent cations (Mg2+, Ca2+), and organic/biological impurities—presents formidable challenges in maintaining both selectivity and durability. Chief among these obstacles is mitigating chloride corrosion and suppressing chlorine evolution reaction (ClER) at the anode, while also preventing the precipitation of magnesium and calcium hydroxides at the cathode. This review consolidates recent advances in material engineering and cell design strategies aimed at controlling undesired side reactions, enhancing electrode stability, and maximizing energy efficiency in DSE. We first outline the fundamental thermodynamic and kinetic hurdles introduced by Cl− and other impurities. This discussion highlights how these factors accelerate catalyst degradation and drive suboptimal reaction pathways. We then delve into innovative approaches to improve selectivity and durability of DSE—such as engineering protective barrier layers, tuning electrolyte interfaces, developing corrosion-resistant materials, and techniques to minimize Mg/Ca-related precipitations. Finally, we explore emerging reactor configurations, including asymmetric and membrane-free electrolyzers, which address some barriers for DSE commercialization. Collectively, these insights provide a framework for designing next-generation DSE systems, which can achieve large-scale, cost-effective, and environmentally benign hydrogen production.
{"title":"Modulating selectivity and stability of the direct seawater electrolysis for sustainable green hydrogen production","authors":"Dazhi Yao , Chun Liu , Yanzhao Zhang , Shuhao Wang , Yan Nie , Man Qiao , Dongdong Zhu","doi":"10.1016/j.mtcata.2025.100089","DOIUrl":"10.1016/j.mtcata.2025.100089","url":null,"abstract":"<div><div>Direct seawater electrolysis (DSE) has emerged as a compelling route to sustainable hydrogen production, leveraging the vast global reserves of seawater. However, the inherently complex composition of seawater—laden with halide ions, multivalent cations (Mg<sup>2</sup><sup>+</sup>, Ca<sup>2+</sup>), and organic/biological impurities—presents formidable challenges in maintaining both selectivity and durability. Chief among these obstacles is mitigating chloride corrosion and suppressing chlorine evolution reaction (ClER) at the anode, while also preventing the precipitation of magnesium and calcium hydroxides at the cathode. This review consolidates recent advances in material engineering and cell design strategies aimed at controlling undesired side reactions, enhancing electrode stability, and maximizing energy efficiency in DSE. We first outline the fundamental thermodynamic and kinetic hurdles introduced by Cl<sup>−</sup> and other impurities. This discussion highlights how these factors accelerate catalyst degradation and drive suboptimal reaction pathways. We then delve into innovative approaches to improve selectivity and durability of DSE—such as engineering protective barrier layers, tuning electrolyte interfaces, developing corrosion-resistant materials, and techniques to minimize Mg/Ca-related precipitations. Finally, we explore emerging reactor configurations, including asymmetric and membrane-free electrolyzers, which address some barriers for DSE commercialization. Collectively, these insights provide a framework for designing next-generation DSE systems, which can achieve large-scale, cost-effective, and environmentally benign hydrogen production.</div></div>","PeriodicalId":100892,"journal":{"name":"Materials Today Catalysis","volume":"8 ","pages":"Article 100089"},"PeriodicalIF":0.0,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-31DOI: 10.1016/j.mtcata.2024.100086
Ruonan Liu , Yaotian Yan , Liang Dun , Taili Yang , Bin Qin , Peijia Wang , Wei Cai , Shude Liu , Xiaohang Zheng
Transition metal oxides hold great potential for water splitting due to their tunable electronic structures and abundant availability. However, their inherently poor electrical conductivity and limited catalytic activity hinder their practical implementation. Herein, high-entropy oxide (FeCoNiCrCuO) electrocatalysts featuring grain-like structure and oxygen vacancies-enriched surface were synthesized through an ultra-fast non-equilibrium high-temperature shock. The introduction of oxygen vacancies modulates the electronic structure and increases the carrier concentration, accelerating the rate-determining step of the oxygen evolution reactions and reducing the overpotential of oxygen evolution reactions. Consequently, the synthesized FeCoNiCrCuO electrocatalyst delivers a low overpotential of 256 mV at a current density of 10 mA·cm⁻² and a Tafel slope of 48.2 mV·dec⁻¹ in 1 M KOH, which is superior to samples lacking oxygen vacancies after annealing. This study presents an alternative approach to enhancing OER activity by employing a high-entropy oxide engineering strategy.
过渡金属氧化物由于其可调谐的电子结构和丰富的可用性而具有很大的水裂解潜力。然而，它们固有的导电性差和有限的催化活性阻碍了它们的实际应用。本文采用超快速非平衡高温冲击法制备了具有晶粒状结构、表面富氧空位的高熵氧化物（FeCoNiCrCuO）电催化剂。氧空位的引入调节了电子结构，增加了载流子浓度，加快了析氧反应的速率决定步骤，降低了析氧反应的过电位。因此，合成的FeCoNiCrCuO电催化剂在电流密度为10 mA·cm⁻²时的过电位为256 mV，在1 M KOH条件下的Tafel斜率为48.2 mV·dec⁻¹ ，优于退火后缺乏氧空位的样品。本研究提出了一种通过采用高熵氧化物工程策略来提高OER活性的替代方法。
{"title":"Oxygen vacancy-mediated high-entropy oxide electrocatalysts for efficient oxygen evolution reaction","authors":"Ruonan Liu , Yaotian Yan , Liang Dun , Taili Yang , Bin Qin , Peijia Wang , Wei Cai , Shude Liu , Xiaohang Zheng","doi":"10.1016/j.mtcata.2024.100086","DOIUrl":"10.1016/j.mtcata.2024.100086","url":null,"abstract":"<div><div>Transition metal oxides hold great potential for water splitting due to their tunable electronic structures and abundant availability. However, their inherently poor electrical conductivity and limited catalytic activity hinder their practical implementation. Herein, high-entropy oxide (FeCoNiCrCuO) electrocatalysts featuring grain-like structure and oxygen vacancies-enriched surface were synthesized through an ultra-fast non-equilibrium high-temperature shock. The introduction of oxygen vacancies modulates the electronic structure and increases the carrier concentration, accelerating the rate-determining step of the oxygen evolution reactions and reducing the overpotential of oxygen evolution reactions. Consequently, the synthesized FeCoNiCrCuO electrocatalyst delivers a low overpotential of 256 mV at a current density of 10 mA·cm⁻² and a Tafel slope of 48.2 mV·dec⁻¹ in 1 M KOH, which is superior to samples lacking oxygen vacancies after annealing. This study presents an alternative approach to enhancing OER activity by employing a high-entropy oxide engineering strategy.</div></div>","PeriodicalId":100892,"journal":{"name":"Materials Today Catalysis","volume":"8 ","pages":"Article 100086"},"PeriodicalIF":0.0,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-27DOI: 10.1016/j.mtcata.2024.100085
Evgenia Kountoupi , Diana Piankova , Mikhail Agrachev , Zixuan Chen , Alberto Garbujo , Paula M. Abdala , Christoph R. Müller , Alexey Fedorov
Harnessing two-dimensional (2D) materials for catalytic applications is promising due to the high site utilization. Here, we synthesized a 2D molybdenum carbonitride of the MXene family, Mo2(C,N)Tx, and applied it as a catalyst for ammonia synthesis and decomposition, the essential reactions to establish NH3 as an energy vector. We determine the thermal stability limit of Mo2(C,N)Tx under H2 flow to be ca. 575 °C. Exceeding this temperature results, under H2, in a transformation of the predominantly defunctionalized Mo2(C,N)Tx to a 3D Mo2(C,N) phase, which prevents the complete defunctionalization of Mo2(C,N)Tx while retaining its 2D morphology. Before this phase transformation occurs, the remaining Tx species reside in the interior layers of the mostly defunctionalized Mo2(C,N)Tx nanoplatelets, with the amorphous exterior being free from Tx groups, rendering the Mo2(C,N)Tx nanoplatelets chemically anisotropic in the direction orthogonal to the basal plane. The effect of this structure on catalytic properties is highlighted in the thermocatalytic synthesis and decomposition of NH3. In the latter reaction, Mo2(C,N)Tx shows similar gravimetric rates to a reference bulk β-Μο2Ν catalyst, which is ascribed to the presence of too narrow 2D pores (ca. 5.2 Å) with irregular shapes due to a disorder in the stacking of nanosheets in Mo2(C,N)Tx, limiting interlayer diffusion. A deactivation pathway in Mo-based MXenes was identified, and it relates to a precipitation of carbon vacancies to metallic molybdenum under NH3 decomposition conditions. While the ammonia decomposition reaction shows no dependence of the reaction rate on the specific H2 pretreatment of Mo2(C,N)Tx (500 or 575 °C), the gravimetric ammonia formation rate increases appreciably with H2 pretreatment, viz., Mo2(C,N)Tx pretreated at 575 °C outperforms by ca. four times both the reference β-Μο2Ν catalyst and Mo2(C,N)Tx pretreated at 500 °C, explained by a smaller molecule size of the reactants H2 and N2 relative to NH3, and an increased accessibility and utilization of the interlayer space for ammonia synthesis. Overall, our study highlights the importance of addressing limitations due to small pore sizes in multilayered MXenes and the stability of carbon vacancies while simultaneously using optimized pretreatment conditions for surface defunctio
{"title":"Multilayered molybdenum carbonitride MXene: Reductive defunctionalization, thermal stability, and catalysis of ammonia synthesis and decomposition","authors":"Evgenia Kountoupi , Diana Piankova , Mikhail Agrachev , Zixuan Chen , Alberto Garbujo , Paula M. Abdala , Christoph R. Müller , Alexey Fedorov","doi":"10.1016/j.mtcata.2024.100085","DOIUrl":"10.1016/j.mtcata.2024.100085","url":null,"abstract":"<div><div>Harnessing two-dimensional (2D) materials for catalytic applications is promising due to the high site utilization. Here, we synthesized a 2D molybdenum carbonitride of the MXene family, Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub>, and applied it as a catalyst for ammonia synthesis and decomposition, the essential reactions to establish NH<sub>3</sub> as an energy vector. We determine the thermal stability limit of Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> under H<sub>2</sub> flow to be ca. 575 °C. Exceeding this temperature results, under H<sub>2</sub>, in a transformation of the predominantly defunctionalized Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> to a 3D Mo<sub>2</sub>(C,N) phase, which prevents the complete defunctionalization of Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> while retaining its 2D morphology. Before this phase transformation occurs, the remaining <em>T</em><sub><em>x</em></sub> species reside in the interior layers of the mostly defunctionalized Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> nanoplatelets, with the amorphous exterior being free from <em>T</em><sub><em>x</em></sub> groups, rendering the Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> nanoplatelets chemically anisotropic in the direction orthogonal to the basal plane. The effect of this structure on catalytic properties is highlighted in the thermocatalytic synthesis and decomposition of NH<sub>3</sub>. In the latter reaction, Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> shows similar gravimetric rates to a reference bulk β-Μο<sub>2</sub>Ν catalyst, which is ascribed to the presence of too narrow 2D pores (ca. 5.2 Å) with irregular shapes due to a disorder in the stacking of nanosheets in Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub>, limiting interlayer diffusion. A deactivation pathway in Mo-based MXenes was identified, and it relates to a precipitation of carbon vacancies to metallic molybdenum under NH<sub>3</sub> decomposition conditions. While the ammonia decomposition reaction shows no dependence of the reaction rate on the specific H<sub>2</sub> pretreatment of Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> (500 or 575 °C), the gravimetric ammonia formation rate increases appreciably with H<sub>2</sub> pretreatment, <em>viz</em>., Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> pretreated at 575 °C outperforms by ca. four times both the reference β-Μο<sub>2</sub>Ν catalyst and Mo<sub>2</sub>(C,N)<em>T</em><sub><em>x</em></sub> pretreated at 500 °C, explained by a smaller molecule size of the reactants H<sub>2</sub> and N<sub>2</sub> relative to NH<sub>3</sub>, and an increased accessibility and utilization of the interlayer space for ammonia synthesis. Overall, our study highlights the importance of addressing limitations due to small pore sizes in multilayered MXenes and the stability of carbon vacancies while simultaneously using optimized pretreatment conditions for surface defunctio","PeriodicalId":100892,"journal":{"name":"Materials Today Catalysis","volume":"8 ","pages":"Article 100085"},"PeriodicalIF":0.0,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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