{"title":"跟踪 MnMoO4 微晶电(预)催化剂介导的 OER 活性阶段和反应途径","authors":"Anubha Rajput, Ankita Kumari, Hirak Kumar Basak, Dibyajyoti Ghosh, Biswarup Chakraborty","doi":"10.1039/d4ta05985a","DOIUrl":null,"url":null,"abstract":"MnMoO4 is a barely explored material for electrocatalytic oxygen evolution reaction (OER) and in-situ tracking of the reactive intermediates and final active species during OER in an alkaline pH lacks a sequential study. Herein, in-situ spectroscopic and ex-situ microscopic studies unravel a pH-dependent [MoO4]2- dissolution from MnMoO4 with a kobs of 4.5 s-1 to form α-MnO2 and subsequent potential-driven anodic transformation to δ-MnO2. The electrochemically derived δ-MnO2 delivers a fairly stable current density (15 mA cm-2) at 1.55 V (vs RHE) for over 24 h. However, a thermally stable mixed-phase α/δ-MnO2 species evolved during OER with dominant MnIII content and remains highly reactive toward OER with η10 at 333 K of 239 mV. Temperature-dependent OER study provides an unimolecular reaction order for [OH]- and an anodic transfer coefficient (a) of 0.7. A low activation barrier of 9.77 k J mol-1 and a high exchange current density (j0) of 0.095 mA cm-2 validate that the improved OER activity on α/δ-MnO2 is due to fast electro-kinetics. DFT study on the (21 @#x0305;(1 ) @#x0305;6) surface of the δ-MnO2 concluded that the dissociation of the *O-H bond to form the *O is the rate-limiting for OER and the *O intermediate is stabilized by a weak O—O interaction (1.4 Å) with one lattice-oxygen before forming a hydroperoxide intermediate. Herein, in-situ tracking of the reactive phases generated from the MnMoO4 pre-catalyst, detailed electro-kinetics, and the theoretical study help to unravel the OER mechanism.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":null,"pages":null},"PeriodicalIF":10.7000,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Tracking the Active Phase and Reaction Pathway of OER Mediated by MnMoO4 Microrod Electro(Pre)-catalyst\",\"authors\":\"Anubha Rajput, Ankita Kumari, Hirak Kumar Basak, Dibyajyoti Ghosh, Biswarup Chakraborty\",\"doi\":\"10.1039/d4ta05985a\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"MnMoO4 is a barely explored material for electrocatalytic oxygen evolution reaction (OER) and in-situ tracking of the reactive intermediates and final active species during OER in an alkaline pH lacks a sequential study. Herein, in-situ spectroscopic and ex-situ microscopic studies unravel a pH-dependent [MoO4]2- dissolution from MnMoO4 with a kobs of 4.5 s-1 to form α-MnO2 and subsequent potential-driven anodic transformation to δ-MnO2. The electrochemically derived δ-MnO2 delivers a fairly stable current density (15 mA cm-2) at 1.55 V (vs RHE) for over 24 h. However, a thermally stable mixed-phase α/δ-MnO2 species evolved during OER with dominant MnIII content and remains highly reactive toward OER with η10 at 333 K of 239 mV. Temperature-dependent OER study provides an unimolecular reaction order for [OH]- and an anodic transfer coefficient (a) of 0.7. A low activation barrier of 9.77 k J mol-1 and a high exchange current density (j0) of 0.095 mA cm-2 validate that the improved OER activity on α/δ-MnO2 is due to fast electro-kinetics. DFT study on the (21 @#x0305;(1 ) @#x0305;6) surface of the δ-MnO2 concluded that the dissociation of the *O-H bond to form the *O is the rate-limiting for OER and the *O intermediate is stabilized by a weak O—O interaction (1.4 Å) with one lattice-oxygen before forming a hydroperoxide intermediate. Herein, in-situ tracking of the reactive phases generated from the MnMoO4 pre-catalyst, detailed electro-kinetics, and the theoretical study help to unravel the OER mechanism.\",\"PeriodicalId\":82,\"journal\":{\"name\":\"Journal of Materials Chemistry A\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":10.7000,\"publicationDate\":\"2024-10-14\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Materials Chemistry A\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://doi.org/10.1039/d4ta05985a\",\"RegionNum\":2,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Materials Chemistry A","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1039/d4ta05985a","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
摘要
锰氧化物(MnMoO4)是一种几乎未被开发的电催化氧进化反应(OER)材料,缺乏对碱性 pH 下 OER 反应过程中反应中间产物和最终活性物种的原位跟踪研究。在本文中,原位光谱和原位显微镜研究揭示了[MoO4]2-从 MnMoO4 中溶解形成 α-MnO2 的过程与 pH 值的关系,其 kobs 为 4.5 s-1,随后电位驱动阳极转化为 δ-MnO2。电化学衍生的 δ-MnO2 在 1.55 V(相对于 RHE)电压下提供了相当稳定的电流密度(15 mA cm-2),持续时间超过 24 小时。然而,在 OER 过程中演化出了一种热稳定的 α/δ-MnO2 混合相,其中 MnIII 含量占主导地位,并且对 OER 仍具有高反应性,η10 在 333 K 时为 239 mV。随温度变化的 OER 研究提供了[OH]- 的单分子反应顺序和 0.7 的阳极转移因子 (a)。9.77 k J mol-1 的低活化势垒和 0.095 mA cm-2 的高交换电流密度 (j0) 证明,α/δ-MnO2 的 OER 活性的提高是由于快速的电动力学。对 δ-MnO2 的 (21 @#x0305;(1 ) @#x0305;6) 表面进行的 DFT 研究得出结论:*O-H 键解离形成 *O 是 OER 的限速过程,*O 中间体在形成过氧化氢中间体之前通过与一个晶格氧的弱 O-O 相互作用(1.4 Å)而稳定下来。在这里,对 MnMoO4 前催化剂生成的反应相进行原位跟踪、详细的电动力学和理论研究有助于揭示 OER 机理。
Tracking the Active Phase and Reaction Pathway of OER Mediated by MnMoO4 Microrod Electro(Pre)-catalyst
MnMoO4 is a barely explored material for electrocatalytic oxygen evolution reaction (OER) and in-situ tracking of the reactive intermediates and final active species during OER in an alkaline pH lacks a sequential study. Herein, in-situ spectroscopic and ex-situ microscopic studies unravel a pH-dependent [MoO4]2- dissolution from MnMoO4 with a kobs of 4.5 s-1 to form α-MnO2 and subsequent potential-driven anodic transformation to δ-MnO2. The electrochemically derived δ-MnO2 delivers a fairly stable current density (15 mA cm-2) at 1.55 V (vs RHE) for over 24 h. However, a thermally stable mixed-phase α/δ-MnO2 species evolved during OER with dominant MnIII content and remains highly reactive toward OER with η10 at 333 K of 239 mV. Temperature-dependent OER study provides an unimolecular reaction order for [OH]- and an anodic transfer coefficient (a) of 0.7. A low activation barrier of 9.77 k J mol-1 and a high exchange current density (j0) of 0.095 mA cm-2 validate that the improved OER activity on α/δ-MnO2 is due to fast electro-kinetics. DFT study on the (21 @#x0305;(1 ) @#x0305;6) surface of the δ-MnO2 concluded that the dissociation of the *O-H bond to form the *O is the rate-limiting for OER and the *O intermediate is stabilized by a weak O—O interaction (1.4 Å) with one lattice-oxygen before forming a hydroperoxide intermediate. Herein, in-situ tracking of the reactive phases generated from the MnMoO4 pre-catalyst, detailed electro-kinetics, and the theoretical study help to unravel the OER mechanism.
期刊介绍:
The Journal of Materials Chemistry A, B & C covers a wide range of high-quality studies in the field of materials chemistry, with each section focusing on specific applications of the materials studied. Journal of Materials Chemistry A emphasizes applications in energy and sustainability, including topics such as artificial photosynthesis, batteries, and fuel cells. Journal of Materials Chemistry B focuses on applications in biology and medicine, while Journal of Materials Chemistry C covers applications in optical, magnetic, and electronic devices. Example topic areas within the scope of Journal of Materials Chemistry A include catalysis, green/sustainable materials, sensors, and water treatment, among others.