The recently proposed golden overpotential provides a characteristic reference point for symmetric Butler-Volmer (BV) kinetics, but its utility is critically limited by the assumption of a transfer coefficient α = 1/2. Deviations introduce systematic errors in exchange-current estimation and leave discrepancies beyond α-adjustment unexplained. Here, we overcome this limitation by showing that the golden reference is fundamentally geometric, not amplitude-specific. Resolving BV kinetics into positive anodic/cathodic channels recasts the golden overpotential as an invariant competition state. Kinetic asymmetry preserves this normalized state while rescaling the current magnitude, enabling exact branch-aware correction of the golden-current estimate and establishing a bounded admissibility window (0.618-1.618) for deviations solely attributable to α-asymmetry. Deviations outside this window signal additional interfacial physics or model inadequacy. This framework thus transforms the golden overpotential from a symmetric reference into a general diagnostic criterion, quantitative correction principle, and falsifiable test for electrochemical materials kinetics.
{"title":"Golden competition states in Butler–Volmer kinetics: exact asymmetry correction and a formal consistency bound","authors":"Bi-Shuang Chen,Huayang Cai","doi":"10.1039/d6ta07464b","DOIUrl":"https://doi.org/10.1039/d6ta07464b","url":null,"abstract":"The recently proposed golden overpotential provides a characteristic reference point for symmetric Butler-Volmer (BV) kinetics, but its utility is critically limited by the assumption of a transfer coefficient α = 1/2. Deviations introduce systematic errors in exchange-current estimation and leave discrepancies beyond α-adjustment unexplained. Here, we overcome this limitation by showing that the golden reference is fundamentally geometric, not amplitude-specific. Resolving BV kinetics into positive anodic/cathodic channels recasts the golden overpotential as an invariant competition state. Kinetic asymmetry preserves this normalized state while rescaling the current magnitude, enabling exact branch-aware correction of the golden-current estimate and establishing a bounded admissibility window (0.618-1.618) for deviations solely attributable to α-asymmetry. Deviations outside this window signal additional interfacial physics or model inadequacy. This framework thus transforms the golden overpotential from a symmetric reference into a general diagnostic criterion, quantitative correction principle, and falsifiable test for electrochemical materials kinetics.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"11 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the true active sites and structure-performance relationships of Cu-based catalysts in electrochemical nitrate reduction reaction (NO3RR) remains challenging due to the dynamic reconstruction of copper oxides under operating conditions. Herein, density functional theory calculations combined with ab initio molecular dynamics, surface Pourbaix analysis, and microkinetic simulations were employed to systematically investigate the coupled effects of catalyst reconstruction, applied potential, and pH on NO3RR over Cu2O-derived surfaces. Progressive reduction of Cu2O induces substantial structural reconstruction and generates a series of defect-rich surfaces with distinct active-site configurations. The reconstructed surfaces exhibit markedly different NO3RR mechanisms and pathway distributions, governed by the transformation behavior of key intermediates such as *NO2 + *OH. The results reveal that deeply reduced surfaces expose pentagonal defect sites and square-step sites that serve as the primary active centers for NO3RR. Importantly, NH3 selectivity is found to be predominantly determined by the active-site configuration, while the competition between NO3RR and the hydrogen evolution reaction is mainly regulated by the applied potential and pH. Moderate cathodic potentials under acidic conditions provide the optimal balance between catalytic activity and NO3RR competitiveness. This work establishes a comprehensive framework that explicitly incorporates catalyst reconstruction and operating conditions into mechanistic analysis, offering atomic-level insight into the origin of NO3RR performance on Cu2O-derived catalysts and guiding the rational design of efficient nitrate reduction electrocatalysts.
{"title":"Origins of NO3RR Activity and Selectivity on Cu2O-Derived Catalysts: Interplay of Oxidation States, Surface Reconstruction, and Reaction Conditions","authors":"Han Zhou,Neil Qiang Su","doi":"10.1039/d6ta07588f","DOIUrl":"https://doi.org/10.1039/d6ta07588f","url":null,"abstract":"Understanding the true active sites and structure-performance relationships of Cu-based catalysts in electrochemical nitrate reduction reaction (NO3RR) remains challenging due to the dynamic reconstruction of copper oxides under operating conditions. Herein, density functional theory calculations combined with ab initio molecular dynamics, surface Pourbaix analysis, and microkinetic simulations were employed to systematically investigate the coupled effects of catalyst reconstruction, applied potential, and pH on NO3RR over Cu2O-derived surfaces. Progressive reduction of Cu2O induces substantial structural reconstruction and generates a series of defect-rich surfaces with distinct active-site configurations. The reconstructed surfaces exhibit markedly different NO3RR mechanisms and pathway distributions, governed by the transformation behavior of key intermediates such as *NO2 + *OH. The results reveal that deeply reduced surfaces expose pentagonal defect sites and square-step sites that serve as the primary active centers for NO3RR. Importantly, NH3 selectivity is found to be predominantly determined by the active-site configuration, while the competition between NO3RR and the hydrogen evolution reaction is mainly regulated by the applied potential and pH. Moderate cathodic potentials under acidic conditions provide the optimal balance between catalytic activity and NO3RR competitiveness. This work establishes a comprehensive framework that explicitly incorporates catalyst reconstruction and operating conditions into mechanistic analysis, offering atomic-level insight into the origin of NO3RR performance on Cu2O-derived catalysts and guiding the rational design of efficient nitrate reduction electrocatalysts.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"4 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kai ang Su,Xie Fei,Haocun Guan,Xiaoqian Su,Saihua Jiang,Congling Shi,Xiaodong Qian
Solid-state sodium metal batteries with high energy density are promising candidates for next-generation energy storage systems. Their bottleneck lies in the solid electrolytes, which must ensure flawless solid-solid contact and electrochemical compatibility with the Na anode and sufficient Na+ conductivity at room temperature. Herein, an in-situ polymerized hetero-layered quasi-solid-state electrolyte, denoted as PANO-SN, was developed by integrating a mechanically reinforced polyacrylonitrile (PAN)/Na3Zr2Si2PO12 (NZSPO) inner framework with in situ polymerized succinonitrile (SN)-based deep-eutectic interfacial layers. the resulting PANO-SN electrolyte achieves an ionic conductivity of 2.4 × 10-4 S cm-1 and an enhanced Na+ transference number of 0.61 at room temperature. When assembled Na|PANO-SN|Na symmetric cell, the batteries maintain stable Na plating/stripping for over 1200 h at 0.1 mA cm-2 with a stable polarization voltage of approximately 0.4 V. Furthermore, the Na|PANO-SN|NVP full cell delivers an excellent cyclability with 97.8% capacity retention after 400 cycles at 0.5 C. Notably, the fluoroethylene carbonate (FEC) containing deep-eutectic interfacial layer facilitates the generation of a stable NaF and Na3Nrich solid electrolyte interphase (SEI), restraining parasitic side reactions and homogenizing sodiumion flux. This work offers a rational strategy for developing mechanically robust, interfacially compatible, and ionically conductive quasi-solid-state electrolytes for high-performance sodium-metal batteries.
具有高能量密度的固态金属钠电池是下一代储能系统的理想选择。它们的瓶颈在于固体电解质，它必须保证完美的固-固接触和与Na阳极的电化学相容性，以及在室温下足够的Na+导电性。本文通过将机械增强聚丙烯腈(PAN)/Na3Zr2Si2PO12 （NZSPO）内部框架与原位聚合丁二腈（SN）基深共晶界面层集成在一起，制备了原位聚合异层准固态电解质PANO-SN。得到的PANO-SN电解质在室温下离子电导率为2.4 × 10-4 S cm-1， Na+转移数增强为0.61。当组装Na|PANO-SN|Na对称电池时，电池在0.1 mA cm-2下稳定镀/剥离超过1200 h，极化电压约为0.4 V。此外，在0.5℃下循环400次后，Na|PANO-SN|NVP全电池具有良好的循环性能，容量保持率为97.8%。值得注意的是，含有深共晶界面层的氟碳酸乙烯（FEC）有助于生成稳定的NaF和富na3nsolid电解质界面相（SEI），抑制了寄生副反应并均匀化了钠离子通量。这项工作为开发用于高性能钠金属电池的机械坚固，界面兼容和离子导电的准固态电解质提供了合理的策略。
{"title":"In Situ Hetero-Layered Quasi-Solid-State Electrolyte Enable Enhanced Ion Transport for Safe Sodium Metal Batteries","authors":"Kai ang Su,Xie Fei,Haocun Guan,Xiaoqian Su,Saihua Jiang,Congling Shi,Xiaodong Qian","doi":"10.1039/d6ta06891j","DOIUrl":"https://doi.org/10.1039/d6ta06891j","url":null,"abstract":"Solid-state sodium metal batteries with high energy density are promising candidates for next-generation energy storage systems. Their bottleneck lies in the solid electrolytes, which must ensure flawless solid-solid contact and electrochemical compatibility with the Na anode and sufficient Na+ conductivity at room temperature. Herein, an in-situ polymerized hetero-layered quasi-solid-state electrolyte, denoted as PANO-SN, was developed by integrating a mechanically reinforced polyacrylonitrile (PAN)/Na3Zr2Si2PO12 (NZSPO) inner framework with in situ polymerized succinonitrile (SN)-based deep-eutectic interfacial layers. the resulting PANO-SN electrolyte achieves an ionic conductivity of 2.4 × 10-4 S cm-1 and an enhanced Na+ transference number of 0.61 at room temperature. When assembled Na|PANO-SN|Na symmetric cell, the batteries maintain stable Na plating/stripping for over 1200 h at 0.1 mA cm-2 with a stable polarization voltage of approximately 0.4 V. Furthermore, the Na|PANO-SN|NVP full cell delivers an excellent cyclability with 97.8% capacity retention after 400 cycles at 0.5 C. Notably, the fluoroethylene carbonate (FEC) containing deep-eutectic interfacial layer facilitates the generation of a stable NaF and Na3Nrich solid electrolyte interphase (SEI), restraining parasitic side reactions and homogenizing sodiumion flux. This work offers a rational strategy for developing mechanically robust, interfacially compatible, and ionically conductive quasi-solid-state electrolytes for high-performance sodium-metal batteries.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"33 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electrochemical CO2 reduction reaction (eCO2RR) has been widely regarded as a promising approach to address environmental issues associated with rising atmospheric CO2 levels. Recently we have reported a bottom-up synthesis of carbon materials by solid-phase polymerization using functional molecules with thermopolymerizable groups as precursors. Here, by utilizing the technique, ethynyl-functionalized nickel porphyrin was employed as a molecular precursor to synthesize carbon-based catalysts, whose eCO2RR performance was systematically evaluated. Using three different carbon supports, catalysts retaining the Ni-N4 coordination structure were successfully obtained in all cases. Notably, the use of a mesoporous carbon support (CNovel® 010-00) enabled high CO selectivity and suppressed hydrogen evolution over a wide current density range of 10-100 mA cm⁻². These results demonstrate the effectiveness of this strategy for enhancing the electrocatalytic performance of metal porphyrin-based catalysts and highlight its potential for further improvement through precursor design and support optimization.
电化学CO2还原反应（eCO2RR）被广泛认为是解决大气CO2浓度上升引起的环境问题的一种有前途的方法。最近，我们报道了一种以具有热聚合基团的功能分子为前体，采用固相聚合自下而上合成碳材料的方法。本研究利用该技术，以乙基功能化的卟啉镍为分子前驱体合成了碳基催化剂，并对其eCO2RR性能进行了系统评价。在三种不同的碳载体下，均成功获得了保留Ni-N4配位结构的催化剂。值得注意的是，使用中孔碳载体（CNovel®010-00）可以实现高CO选择性，并在10-100 mA cm⁻²的宽电流密度范围内抑制氢的析出。这些结果证明了该策略在提高金属卟啉基催化剂电催化性能方面的有效性，并强调了通过前驱体设计和载体优化进一步改进该策略的潜力。
{"title":"Bottom-up carbon material synthesis from Ni-porphyrin with thermally polymerizable functional groups: Influence of carbon supports and application as CORR electrocatalysts","authors":"Yuki Sano,Haruko Moteki,Miyu Tanaka,Ryojun Toyoda,Tomoki Tateishi,Shinya Takaishi,Kazuyuki Iwase,Yuta Nishina,Ryota Sakamoto","doi":"10.1039/d6ta05221e","DOIUrl":"https://doi.org/10.1039/d6ta05221e","url":null,"abstract":"Electrochemical CO2 reduction reaction (eCO2RR) has been widely regarded as a promising approach to address environmental issues associated with rising atmospheric CO2 levels. Recently we have reported a bottom-up synthesis of carbon materials by solid-phase polymerization using functional molecules with thermopolymerizable groups as precursors. Here, by utilizing the technique, ethynyl-functionalized nickel porphyrin was employed as a molecular precursor to synthesize carbon-based catalysts, whose eCO2RR performance was systematically evaluated. Using three different carbon supports, catalysts retaining the Ni-N4 coordination structure were successfully obtained in all cases. Notably, the use of a mesoporous carbon support (CNovel® 010-00) enabled high CO selectivity and suppressed hydrogen evolution over a wide current density range of 10-100 mA cm⁻². These results demonstrate the effectiveness of this strategy for enhancing the electrocatalytic performance of metal porphyrin-based catalysts and highlight its potential for further improvement through precursor design and support optimization.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"33 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Novel catalysts featuring a metal–nitrogen–carbon (M–N–C) structure have demonstrated significant application potential in the field of oxygen reduction electrocatalysis, offering broad prospects for advancing energy conversion devices such as fuel cells and metal–air batteries. A dual-metal iron–indium catalyst (FeIn/NC) was successfully prepared by a controlled pyrolysis strategy using a polydopamine-coated metal–organic framework (MOF) as the precursor in this study. This catalyst shows excellent oxygen reduction activity in alkaline solution (E1/2: 0.863 V; JL: 6.84 mA cm−2), matching the catalytic level of commercial Pt/C. Theoretical calculations further indicate that strong p–d orbital hybridization occurs between the Fe 3d orbitals and the In 5p orbitals. This electronic coupling effectively modulates the electronic structure of the catalyst and the position of the d-band center, optimizing the adsorption energies of ORR intermediates and thereby enhancing the intrinsic ORR activity. Furthermore, excellent performance is observed for the zinc–air battery (ZAB) constructed with FeIn/NC, which shows a power density of up to 119.34 mW cm−2 and a specific capacity of 794 mA h g−1. This research confirms that the p–d orbital hybridization strategy can enhance catalytic performance and provides a crucial experimental basis and design ideas toward the exploitation of innovative high-activity oxygen electrocatalytic materials.
具有金属-氮-碳（M-N-C）结构的新型催化剂在氧还原电催化领域显示出巨大的应用潜力，为推进燃料电池、金属-空气电池等能量转换装置提供了广阔的前景。本研究以聚多巴胺包覆金属有机骨架（MOF）为前驱体，采用可控热解策略成功制备了双金属铁铟催化剂（FeIn/NC）。该催化剂在碱性溶液中表现出良好的氧还原活性（E1/2: 0.863 V; JL: 6.84 mA cm−2），达到了商品Pt/C的催化水平。理论计算进一步表明，在Fe 3d轨道和In 5p轨道之间发生了强烈的p-d轨道杂化。这种电子耦合有效地调节了催化剂的电子结构和d带中心的位置，优化了ORR中间体的吸附能，从而提高了ORR的本构活性。此外，用FeIn/NC构建的锌空气电池（ZAB）性能优异，其功率密度高达119.34 mW cm - 2，比容量为794 mA h g - 1。该研究证实了p-d轨道杂化策略可以提高催化性能，为开发创新的高活性氧电催化材料提供了重要的实验基础和设计思路。
{"title":"p-Block metal-induced p–d orbital hybridization enhances the oxygen reduction performance of an Fe–N–C catalyst in zinc–air batteries","authors":"Xiaogeng Feng,Xiaotong Jing,Haiying Dong,Junhao Liu,Ruize Yin,Weijun Shan,Ying Xiong","doi":"10.1039/d6ta06630e","DOIUrl":"https://doi.org/10.1039/d6ta06630e","url":null,"abstract":"Novel catalysts featuring a metal–nitrogen–carbon (M–N–C) structure have demonstrated significant application potential in the field of oxygen reduction electrocatalysis, offering broad prospects for advancing energy conversion devices such as fuel cells and metal–air batteries. A dual-metal iron–indium catalyst (FeIn/NC) was successfully prepared by a controlled pyrolysis strategy using a polydopamine-coated metal–organic framework (MOF) as the precursor in this study. This catalyst shows excellent oxygen reduction activity in alkaline solution (E1/2: 0.863 V; JL: 6.84 mA cm−2), matching the catalytic level of commercial Pt/C. Theoretical calculations further indicate that strong p–d orbital hybridization occurs between the Fe 3d orbitals and the In 5p orbitals. This electronic coupling effectively modulates the electronic structure of the catalyst and the position of the d-band center, optimizing the adsorption energies of ORR intermediates and thereby enhancing the intrinsic ORR activity. Furthermore, excellent performance is observed for the zinc–air battery (ZAB) constructed with FeIn/NC, which shows a power density of up to 119.34 mW cm−2 and a specific capacity of 794 mA h g−1. This research confirms that the p–d orbital hybridization strategy can enhance catalytic performance and provides a crucial experimental basis and design ideas toward the exploitation of innovative high-activity oxygen electrocatalytic materials.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"4 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hirak Kumar Basak,Pandiyan Sivasakthi,Deepak Kumar Sahu,Asit Dutta,Pralok K. Samanta,Biswarup Chakraborty
Electrocatalytic ammonia oxidation reaction (AOR) to nitrogen oxyanion products, [NO2]-, and/or [NO3]- is, although a sustainable alternative to the Ostwald process, scrambling of NOx products is often observed due to sluggish reaction kinetics of the multistep proton-coupled-electron-transfer pathway. Herein, oxygen vacancy-rich cubic-phase ~37 (±10) nm Fe3O4 particles are prepared, and their surface and bulk characteristics are analyzed through various microscopic and spectroscopic techniques. The anode made of Fe3O4 on carbon paper (CP) delivers a limiting current near 1.1 V (vs Hg/HgO) at low NH3 concentration in 0.5 M Na2SO4 while showing a catalytic current at high NH3 concentration, exhibiting AOR and a linear dependence of ja on NH3. AOR in different chronoamperometric (CA) conditions reveals 1.0 V (vs Hg/HgO) as an optimum potential to obtain [NO3]- selectively, while at higher potentials various parallel AOR products, including O2 from the oxygen evolution reaction (OER), are formed. Rotating ring-disk electrode (RRDE) reveals 2.0 (± 0.5) electron transfer with an apparent rate constant (kapp) of 2.1 (±1.3) × 10−3 cm s−1, indicating the first two-electron oxidation of ammonia as a kinetically controlled step, while the variable-temperature AOR studies provide an activation energy of 46- 65 kJ mol-1. The D-labelling study depicts almost 10-fold suppression of the AOR rate, giving a kinetic isotope effect (KIE) value of 7.4, inferring the cumulative contribution of multiple oxidative dehydrogenation steps as the rate-limiting. In situ infrared (IR) and 1H nuclear magnetic resonance (NMR) trapping of AOR intermediates confirm [NO] as one of the key intermediates. In silico study of AOR on the (001) surface of oxygen vacancy-rich Fe3O4 surface further validates that the dehydrogenation of *NH to *N and “N-O” bond formation have the highest energy barrier at anodic potentials, leading to a *[NO] intermediate formation as an energetically favourable process. A relatively less energy This study thereby demonstrates Fe3O4 as a robust catalyst for selective oxidation of NH3 to [NO3]- and provides a comprehensive mechanistic understanding of the AOR pathway.
电催化氨氧化反应（AOR）生成氮氧阴离子产物[NO2]-和/或[NO3]-，虽然是一种可持续的替代奥斯特瓦尔德过程，但由于多步质子耦合电子转移途径的反应动力学缓慢，经常观察到NOx产物的混乱。本文制备了富氧空位~37（±10）nm的立方相Fe3O4颗粒，并通过各种显微和光谱技术分析了其表面和体积特征。在0.5 M Na2SO4溶液中，低NH3浓度下，Fe3O4阳极的极限电流接近1.1 V (vs Hg/HgO)，而在高NH3浓度下，Fe3O4阳极表现出AOR和ja与NH3的线性关系。在不同的时间电流（CA）条件下，AOR显示1.0 V （vs Hg/HgO）是选择性获得[NO3]-的最佳电位，而在更高的电位下，形成多种平行AOR产物，包括析氧反应（OER）产生的O2。旋转环盘电极（RRDE）显示2.0（±0.5）个电子转移，表观速率常数（kapp）为2.1（±1.3）× 10−3 cm s−1，表明氨的第一个双电子氧化是一个动力学控制的步骤，而变温AOR研究提供了46- 65 kJ mol-1的活化能。d标记研究显示，AOR速率几乎被抑制了10倍，动力学同位素效应（KIE）值为7.4，推断出多个氧化脱氢步骤的累积贡献是限速的。AOR中间体的原位红外（IR）和1H核磁共振（NMR）捕获证实[NO]是关键中间体之一。富氧空位Fe3O4表面（001）上AOR的硅研究进一步证实，在阳极电位下，*NH脱氢成*N和“N- o”键形成具有最高的能垒，导致*[NO]中间体形成是一个能量有利的过程。因此，本研究证明了Fe3O4作为NH3选择性氧化为[NO3]-的强大催化剂，并提供了对AOR途径的全面机制理解。
{"title":"Electrooxidation of Ammonia to Nitrate on Magnetite via Slow Dehydrogenation and Nitric Oxide Formation","authors":"Hirak Kumar Basak,Pandiyan Sivasakthi,Deepak Kumar Sahu,Asit Dutta,Pralok K. Samanta,Biswarup Chakraborty","doi":"10.1039/d6ta06280f","DOIUrl":"https://doi.org/10.1039/d6ta06280f","url":null,"abstract":"Electrocatalytic ammonia oxidation reaction (AOR) to nitrogen oxyanion products, [NO2]-, and/or [NO3]- is, although a sustainable alternative to the Ostwald process, scrambling of NOx products is often observed due to sluggish reaction kinetics of the multistep proton-coupled-electron-transfer pathway. Herein, oxygen vacancy-rich cubic-phase ~37 (±10) nm Fe3O4 particles are prepared, and their surface and bulk characteristics are analyzed through various microscopic and spectroscopic techniques. The anode made of Fe3O4 on carbon paper (CP) delivers a limiting current near 1.1 V (vs Hg/HgO) at low NH3 concentration in 0.5 M Na2SO4 while showing a catalytic current at high NH3 concentration, exhibiting AOR and a linear dependence of ja on NH3. AOR in different chronoamperometric (CA) conditions reveals 1.0 V (vs Hg/HgO) as an optimum potential to obtain [NO3]- selectively, while at higher potentials various parallel AOR products, including O2 from the oxygen evolution reaction (OER), are formed. Rotating ring-disk electrode (RRDE) reveals 2.0 (± 0.5) electron transfer with an apparent rate constant (kapp) of 2.1 (±1.3) × 10−3 cm s−1, indicating the first two-electron oxidation of ammonia as a kinetically controlled step, while the variable-temperature AOR studies provide an activation energy of 46- 65 kJ mol-1. The D-labelling study depicts almost 10-fold suppression of the AOR rate, giving a kinetic isotope effect (KIE) value of 7.4, inferring the cumulative contribution of multiple oxidative dehydrogenation steps as the rate-limiting. In situ infrared (IR) and 1H nuclear magnetic resonance (NMR) trapping of AOR intermediates confirm [NO] as one of the key intermediates. In silico study of AOR on the (001) surface of oxygen vacancy-rich Fe3O4 surface further validates that the dehydrogenation of *NH to *N and “N-O” bond formation have the highest energy barrier at anodic potentials, leading to a *[NO] intermediate formation as an energetically favourable process. A relatively less energy This study thereby demonstrates Fe3O4 as a robust catalyst for selective oxidation of NH3 to [NO3]- and provides a comprehensive mechanistic understanding of the AOR pathway.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"33 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Víctor Zapata-Ramírez,Glenn C. Mather,Domingo Pérez-Coll
Bilayer air electrodes offer a route to overcome the activity–stability trade-off that limits intermediate-temperature solid oxide cells, but their performance depends critically on how the individual layers are processed and integrated. Here, spray pyrolysis was used to fabricate compositionally differentiated air electrodes comprising an interfacial SrFe0.9Mo0.1O3−δ layer and an outer SrCo0.95Mo0.05O3−δ layer on Ce0.9Gd0.1O2−δ electrolyte. The resulting porous, well-adhered bilayer exhibited an area-specific polarisation resistance of 0.06 Ω cm2 at 700 °C, lower than either single-layer electrode. Impedance analysis supports complementary functional roles, with the SrCo0.95Mo0.05O3−δ-rich outer layer governing the more active oxygen-reduction response and the SrFe0.9Mo0.1O3−δ interlayer stabilising the electrode–electrolyte interface. The bilayer retained its performance during 100 h of ageing and ten thermal cycles more effectively than single-layer SCM. Importantly, spray pyrolysis reduced the polarisation resistance by more than 50% relative to an analogous slurry-coated bilayer, demonstrating that electrode architecture and fabrication route act cooperatively rather than independently. A Ni–Ce0.9Gd0.1O2−δ-supported cell delivered maximum power densities of 0.48, 0.66 and 0.94 W cm−2 at 650, 700 and 750 °C, respectively, including an approximately 78% improvement over a comparable SrFe0.9Mo0.1O3−δ cell at 650 °C. These results establish processing-enabled functional differentiation as an effective strategy for combining fast oxygen reduction with enhanced interfacial stability in cobalt-lean, rare-earth-free perovskite air electrodes.
双层空气电极提供了一种方法来克服限制中温固体氧化物电池的活性-稳定性权衡，但它们的性能主要取决于各个层的处理和集成方式。本文采用喷雾热解的方法，在Ce0.9Gd0.1O2−δ电解液上制备了由界面层SrFe0.9Mo0.1O3−δ和外层SrCo0.95Mo0.05O3−δ组成的空气电极。所得多孔、粘附良好的双层电极在700°C时的极化电阻为0.06 Ω cm2，低于任何单层电极。阻抗分析支持互补的功能作用，富含SrCo0.95Mo0.05O3−δ的外层控制更活跃的氧还原响应，而SrFe0.9Mo0.1O3−δ中间层稳定电极-电解质界面。在老化100 h和10个热循环中，双层SCM比单层SCM更有效地保持了其性能。重要的是，与类似的浆料涂层双分子层相比，喷雾热解将极化阻力降低了50%以上，这表明电极结构和制造路线是合作的，而不是独立的。Ni-Ce0.9Gd0.1O2−δ支持的电池在650、700和750°C时的功率密度分别为0.48、0.66和0.94 W cm−2，比同类SrFe0.9Mo0.1O3−δ电池在650°C时的功率密度提高了约78%。这些结果表明，在贫钴、无稀土的钙钛矿空气电极中，加工功能分化是一种有效的策略，可以将快速氧还原与增强界面稳定性结合起来。
{"title":"Processing-enabled functional differentiation in spray-pyrolysed bilayer air electrodes for durable solid oxide cells","authors":"Víctor Zapata-Ramírez,Glenn C. Mather,Domingo Pérez-Coll","doi":"10.1039/d6ta06384e","DOIUrl":"https://doi.org/10.1039/d6ta06384e","url":null,"abstract":"Bilayer air electrodes offer a route to overcome the activity–stability trade-off that limits intermediate-temperature solid oxide cells, but their performance depends critically on how the individual layers are processed and integrated. Here, spray pyrolysis was used to fabricate compositionally differentiated air electrodes comprising an interfacial SrFe0.9Mo0.1O3−δ layer and an outer SrCo0.95Mo0.05O3−δ layer on Ce0.9Gd0.1O2−δ electrolyte. The resulting porous, well-adhered bilayer exhibited an area-specific polarisation resistance of 0.06 Ω cm2 at 700 °C, lower than either single-layer electrode. Impedance analysis supports complementary functional roles, with the SrCo0.95Mo0.05O3−δ-rich outer layer governing the more active oxygen-reduction response and the SrFe0.9Mo0.1O3−δ interlayer stabilising the electrode–electrolyte interface. The bilayer retained its performance during 100 h of ageing and ten thermal cycles more effectively than single-layer SCM. Importantly, spray pyrolysis reduced the polarisation resistance by more than 50% relative to an analogous slurry-coated bilayer, demonstrating that electrode architecture and fabrication route act cooperatively rather than independently. A Ni–Ce0.9Gd0.1O2−δ-supported cell delivered maximum power densities of 0.48, 0.66 and 0.94 W cm−2 at 650, 700 and 750 °C, respectively, including an approximately 78% improvement over a comparable SrFe0.9Mo0.1O3−δ cell at 650 °C. These results establish processing-enabled functional differentiation as an effective strategy for combining fast oxygen reduction with enhanced interfacial stability in cobalt-lean, rare-earth-free perovskite air electrodes.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"73 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Proton exchange membrane water electrolysis (PEMWE) is a cornerstone technology for green H2, where the Ti porous transport layer (Ti-PTL) is indispensable for sustaining mechanical integrity in high-pressure stacks. Yet, cathode Ti-PTL degradation remains contentiously attributed to hydrogen embrittlement, a hypothesis inherited from bulk-metal corrosion literature but rarely substantiated at realistic cathodic potentials. By decoupling anode and cathode contributions through an asymmetric Pt-coated-anode/uncoated-cathode configuration, we demonstrate that cathode degradation in PEMWE is governed not by hydride formation but by a previously overlooked “oxidative cathode” paradox, in which the Ti surface undergoes net anodic oxidation even under H2-evolving polarization. Quasi-in situ XPS and in situ Raman spectroscopy resolve the surface evolution at operating cathodic potentials (−0.1 V vs. RHE), identifying sub-stoichiometric, hydroxylated TiOx species that are thermodynamically unstable in the acidic cathodic environment, while ruling out Ti0 and TiHx. The latter species emerge only at potentials (≤−1.0 V) far beyond practical PEMWE cathodes, indicating that hydrogen embrittlement is not the operative mechanism. This unstable oxide thickens, increasing interfacial contact resistance, and dissolves, releasing Ti ions that poison Pt active sites in the cathode catalyst layer. Guided by this mechanism, a magnetron-sputtered carbon coating suppresses both degradation pathways, reducing the electrolyzer degradation rate from 31.9 to 1.9 µV h−1 over 1040 h at 2.0 A cm−2 and enabling operation of a differential-pressure stack at 3.0 MPa. This work redefines the dominant degradation pathway of cathode Ti-PTLs and establishes a mechanistically guided, PGM-free, and cost-effective PTL coating strategy for high-pressure PEMWE stacks.
质子交换膜电解（PEMWE）是绿色H2的基础技术，其中Ti多孔传输层（Ti- ptl）对于维持高压堆的机械完整性是不可或缺的。然而，阴极Ti-PTL降解仍然有争议地归因于氢脆，这一假设继承自大块金属腐蚀文献，但很少在实际阴极电位下得到证实。通过不对称的pt包覆阳极/未包覆阴极结构解耦阳极和阴极的贡献，我们证明了PEMWE中的阴极降解不是由氢化物形成控制的，而是由以前被忽视的“氧化阴极”悖论控制的，其中Ti表面即使在h2演化极化下也会经历净阳极氧化。准原位XPS和原位拉曼光谱分析了工作阴极电位（- 0.1 V vs. RHE）下的表面演变，确定了在酸性阴极环境中热力学不稳定的亚化学计量羟基化TiOx物种，同时排除了Ti0和TiHx。后一种物质仅在电位（≤- 1.0 V）远远超出实际的PEMWE阴极时出现，表明氢脆不是起作用的机制。这种不稳定的氧化物增厚，增加了界面接触电阻，并溶解，释放出钛离子，毒害阴极催化剂层中的铂活性位点。在此机制的指导下，磁控溅射碳涂层抑制了这两种降解途径，在2.0 a cm−2下，在1040小时内将电解槽降解率从31.9降至1.9µV h−1，并使压差堆在3.0 MPa下运行。这项工作重新定义了阴极ti -PTL的主要降解途径，并为高压PEMWE堆建立了一种机械导向的、无pgc的、经济高效的PTL涂层策略。
{"title":"Rethinking cathode porous transport layer degradation in PEM water electrolysis: a mechanism and a carbon-coating solution","authors":"Chen Ju,Congcong Yao,Huimin Sun,Runhao Zhang,Yixuan Ma,Chang Liu,Yang Liu,Ke Zhang,Tianrang Yang,Aidong Tan,Jianguo Liu","doi":"10.1039/d6ta07215a","DOIUrl":"https://doi.org/10.1039/d6ta07215a","url":null,"abstract":"Proton exchange membrane water electrolysis (PEMWE) is a cornerstone technology for green H2, where the Ti porous transport layer (Ti-PTL) is indispensable for sustaining mechanical integrity in high-pressure stacks. Yet, cathode Ti-PTL degradation remains contentiously attributed to hydrogen embrittlement, a hypothesis inherited from bulk-metal corrosion literature but rarely substantiated at realistic cathodic potentials. By decoupling anode and cathode contributions through an asymmetric Pt-coated-anode/uncoated-cathode configuration, we demonstrate that cathode degradation in PEMWE is governed not by hydride formation but by a previously overlooked “oxidative cathode” paradox, in which the Ti surface undergoes net anodic oxidation even under H2-evolving polarization. Quasi-in situ XPS and in situ Raman spectroscopy resolve the surface evolution at operating cathodic potentials (−0.1 V vs. RHE), identifying sub-stoichiometric, hydroxylated TiOx species that are thermodynamically unstable in the acidic cathodic environment, while ruling out Ti0 and TiHx. The latter species emerge only at potentials (≤−1.0 V) far beyond practical PEMWE cathodes, indicating that hydrogen embrittlement is not the operative mechanism. This unstable oxide thickens, increasing interfacial contact resistance, and dissolves, releasing Ti ions that poison Pt active sites in the cathode catalyst layer. Guided by this mechanism, a magnetron-sputtered carbon coating suppresses both degradation pathways, reducing the electrolyzer degradation rate from 31.9 to 1.9 µV h−1 over 1040 h at 2.0 A cm−2 and enabling operation of a differential-pressure stack at 3.0 MPa. This work redefines the dominant degradation pathway of cathode Ti-PTLs and establishes a mechanistically guided, PGM-free, and cost-effective PTL coating strategy for high-pressure PEMWE stacks.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"409 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bin Deng,Mingyue Gao,Donglong Bai,Ao Huang,Yun Zhao,Chuyi Xie,Jianguang Xu,Chi Chen,W Yao
MXenes hold exceptional promise for supercapacitors owing to their high conductivity and 2D layered structure. However, the unavoidable fluorine terminations and structural defects in MXenes synthesized via conventional hydrofluoric acid (HF) etching critically undermine their theoretical energy storage potential. Here, we propose a time-optimized HF etching strategy to synthesize defect-free, low-fluorine MXenes (Nb2CTx and V2CTx) by precisely regulating the interaction dynamics between HF and large-particle MAX precursors. Mechanistic studies reveal that prolonged etching time significantly increases the content of -F functional groups while simultaneously exacerbating the cleavage of Nb-C bonds, whereas controlled termination of the etching process suppresses these effects while ensuring complete Al removal. This approach not only achieves a 60% yield of few-layer MXenes but also eliminates structural damage, resulting in record-breaking electrical conductivity of 5530 S m-1 for Nb2CTx and ultrahigh volumetric capacitance of 1989.57 F cm-3 at 2 mV s-1. The synergy between minimized -F content and intact 2D morphology enables efficient ion diffusion and charge transfer, as evidenced by stable cycling performance, showing 79.55% capacitance retention after 15,000 cycles. Our work establishes a universal paradigm for tailoring MXene surface chemistry and microstructure, paving the way for high-performance energy storage devices.
由于其高导电性和二维分层结构，MXenes在超级电容器方面具有特殊的前景。然而，通过常规氢氟酸（HF）蚀刻合成的MXenes中不可避免的氟终止和结构缺陷严重破坏了它们的理论储能潜力。在此，我们提出了一种时间优化的HF蚀刻策略，通过精确调节HF与大颗粒MAX前体之间的相互作用动力学来合成无缺陷的低氟MXenes （Nb2CTx和V2CTx）。机理研究表明，延长刻蚀时间显著增加了-F官能团的含量，同时加剧了Nb-C键的断裂，而控制刻蚀过程的终止抑制了这些影响，同时确保了Al的完全去除。这种方法不仅实现了60%的少层MXenes产率，而且消除了结构损伤，使Nb2CTx的电导率达到创纪录的5530 S - m-1，在2 mV S -1下的超高体积电容达到1989.57 F cm-3。最小化的-F含量和完整的二维形态之间的协同作用可以实现高效的离子扩散和电荷转移，这可以从稳定的循环性能中得到证明，在15000次循环后，电容保持率达到79.55%。我们的工作为定制MXene表面化学和微观结构建立了一个通用范例，为高性能储能设备铺平了道路。
{"title":"Defect-Free Low-Fluorine MXenes (Nb2CTx/V2CTx) via Time-Optimized HF Etching: Achieving Superior Conductivity and Ultrahigh Capacitance for Supercapacitors","authors":"Bin Deng,Mingyue Gao,Donglong Bai,Ao Huang,Yun Zhao,Chuyi Xie,Jianguang Xu,Chi Chen,W Yao","doi":"10.1039/d6ta05373d","DOIUrl":"https://doi.org/10.1039/d6ta05373d","url":null,"abstract":"MXenes hold exceptional promise for supercapacitors owing to their high conductivity and 2D layered structure. However, the unavoidable fluorine terminations and structural defects in MXenes synthesized via conventional hydrofluoric acid (HF) etching critically undermine their theoretical energy storage potential. Here, we propose a time-optimized HF etching strategy to synthesize defect-free, low-fluorine MXenes (Nb2CTx and V2CTx) by precisely regulating the interaction dynamics between HF and large-particle MAX precursors. Mechanistic studies reveal that prolonged etching time significantly increases the content of -F functional groups while simultaneously exacerbating the cleavage of Nb-C bonds, whereas controlled termination of the etching process suppresses these effects while ensuring complete Al removal. This approach not only achieves a 60% yield of few-layer MXenes but also eliminates structural damage, resulting in record-breaking electrical conductivity of 5530 S m-1 for Nb2CTx and ultrahigh volumetric capacitance of 1989.57 F cm-3 at 2 mV s-1. The synergy between minimized -F content and intact 2D morphology enables efficient ion diffusion and charge transfer, as evidenced by stable cycling performance, showing 79.55% capacitance retention after 15,000 cycles. Our work establishes a universal paradigm for tailoring MXene surface chemistry and microstructure, paving the way for high-performance energy storage devices.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"16 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Encapsulating metals within silica "nanoboxes" offers unique opportunities for controlling catalytic reactions through nanoscale diffusion effects. Here, we systematically investigated the synthesis parameters governing the formation of metalencaged hollow silicalite-1, examining the influence of hydrothermal treatment time, synthesis conditions, additives, metal precursor identity, and turbulence. Statistical analysis of hollow structure-types from large-scale TEM datasets enabled robust quantification of structural distributions, revealing selectivities (often overlooked in the literature but critical for catalytic application). Optimisation of synthesis conditions enabled the preparation of both multihollow (MH) "sponge-like" structures and single-hollow (SH) nanoboxes with selectivities of up to 84% and 72%, respectively. Nitrogen physisorption and solid-state NMR provided complementary signatures of these different hollow architectures: SH-rich samples exhibited a characteristic low-pressure hysteresis loop and lower Q³/Q⁴ ratios, the latter consistent with reduced framework defect concentrations, whereas "sponge-like" MH-rich samples displayed pronounced mesoporosity centred at 5-6 nm. Finally, vapour-phase furfural hydrogenation was used as a test reaction to demonstrate that hollow-structure morphology influences catalytic selectivity, highlighting the role of architecture-dependent diffusion effects and providing a foundation for the rational use of encaged metal particles in catalysis.
{"title":"Understanding the selective synthesis of siliceous zeolite encaged metal particles","authors":"Zixuan Han,Samuel J. Page,Simon Kenneth Beaumont","doi":"10.1039/d6ta06266k","DOIUrl":"https://doi.org/10.1039/d6ta06266k","url":null,"abstract":"Encapsulating metals within silica \"nanoboxes\" offers unique opportunities for controlling catalytic reactions through nanoscale diffusion effects. Here, we systematically investigated the synthesis parameters governing the formation of metalencaged hollow silicalite-1, examining the influence of hydrothermal treatment time, synthesis conditions, additives, metal precursor identity, and turbulence. Statistical analysis of hollow structure-types from large-scale TEM datasets enabled robust quantification of structural distributions, revealing selectivities (often overlooked in the literature but critical for catalytic application). Optimisation of synthesis conditions enabled the preparation of both multihollow (MH) \"sponge-like\" structures and single-hollow (SH) nanoboxes with selectivities of up to 84% and 72%, respectively. Nitrogen physisorption and solid-state NMR provided complementary signatures of these different hollow architectures: SH-rich samples exhibited a characteristic low-pressure hysteresis loop and lower Q³/Q⁴ ratios, the latter consistent with reduced framework defect concentrations, whereas \"sponge-like\" MH-rich samples displayed pronounced mesoporosity centred at 5-6 nm. Finally, vapour-phase furfural hydrogenation was used as a test reaction to demonstrate that hollow-structure morphology influences catalytic selectivity, highlighting the role of architecture-dependent diffusion effects and providing a foundation for the rational use of encaged metal particles in catalysis.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":"159 1","pages":""},"PeriodicalIF":11.9,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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