Polyoxometalate-Based Electrocatalysts for Anodes in Electrolytic Water Splitting

用于电解水分解阳极的多金属氧酸盐基电催化剂

• 批准号: 2282809
• 金额: --
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2282809
• 关键词: Polyoxometalate; Based; Electrocatalysts; Anodes; Electrolytic

Background Polyoxometalates (POMs) are molecular metal oxides with the general formula [MxOy]n- where M = V, Nb, Ta, W or Mo and it is possible to substitute M for other metals and to remove or substitute oxygen for other groups. POMs in which one or more M atoms are replaced with other transition metals have been shown to catalyse water oxidation, which is a vital step in the production of hydrogen from water - a key process for renewable energy conversion and storage. Aims This project aims to provide a platform for detailed mechanistic studies of water activation at substituted POMs, leading to a theoretical understanding of the electron- and proton-transfer processes involved, the design of active catalysts and their use in a new type of electrolyser.Objectives 1. Preparation of reactive transition-metal-substituted POMs based on the Lindqvist-type {M6} structure.Transition-metal-substituted POMs have potential as highly active, stable water oxidation catalysts, and those studied to date have large structures containing upwards of 22 metal atoms. In order to gain insight into how these compounds react with water we will develop a series of simpler transition metal containing POMs based on the simpler Lindqvist structure, with only six metal atoms (Figure 1). This will allow us to probe more easily the important interactions between these POMs and water during oxidation catalysis.Novel procedures previously used by our group to access the cobalt-substituted POM [(CoW5O18H)2]6- (Figure 1) will be adapted in order access new {M'M5} POMs, using organic cations to impart solubility in non-aqueous solvents (Eur. J. Inorg. Chem., 2009, 5240-5246). Initial targets will be {MW5} analogues containing manganese, iron or ruthenium, and attempts will then be made to extend the series to {MMo5} molybdates.In addition to elemental microanalysis, the {M'M5} structure will be confirmed by infrared spectroscopy and single-crystal X-ray crystallography. In addition, X-ray absorption spectroscopy (XAS) will be used to probe structure and oxidation states in solution and in the solid state. While the use of multinuclear NMR atom is likely to be limited for paramagnetic compounds, EPR will provide information about spin states of the anions. Linear and cyclic voltammetry studies will establish the redox properties of the POMs and determine whether they have the appropriate potentials to drive water oxidation. 2. Theoretical understanding of the effects on reactivity of metal substitution in {M'M5} Lindqvist POMs.Density Functional Theory (DFT) modelling of our POMs will be carried out in parallel with experimental studies with the assistance of a newly appointed PDRA from the Poblet group at URV, Tarragona. The studies will provide insight into how the transition metal present in the POM structure influences the interaction with water by examining energies associated with proton and electron transfers, and the calculated redox potentials and electrostatic potential distributions can be tested experimentally. Computational modelling of POM water oxidation should be easier with the smaller Lindqvist POMs, but such systems have received little attention to date.3. Incorporation of active POMs as redox mediators into an electrolytic cell. The end goal of the project is to develop effective water oxidation catalysts that can be used in a working electrolytic cell for water splitting. Electrolysis experiments will be carried out with Dr Mohamed Mamlouk, a chemical engineer with extensive experience of fuel cell and electrolyser design and testing. The role of the POMs is to reduce the oxygen evolution over-potential and thereby increase the efficiency of the electrolysis process.

多金属氧酸盐（pom）是分子式为[MxOy]n-的分子金属氧化物，其中M = V、Nb、Ta、W或Mo，可以用M代替其他金属，并去除或取代其他基团的氧。其中一个或多个M原子被其他过渡金属取代的pom已被证明可以催化水氧化，这是从水中生产氢的关键步骤-这是可再生能源转换和储存的关键过程。本项目旨在为水在取代聚甲醛上的活化机理的详细研究提供一个平台，导致对所涉及的电子和质子转移过程的理论理解，活性催化剂的设计及其在新型电解槽中的应用。目标1。基于lindqvist型{M6}结构的反应性过渡金属取代pom的制备。过渡金属取代的聚甲醛具有作为高活性、稳定的水氧化催化剂的潜力，迄今为止所研究的那些具有包含22个以上金属原子的大结构。为了深入了解这些化合物是如何与水反应的，我们将基于更简单的Lindqvist结构（只有六个金属原子）开发一系列更简单的含过渡金属的POMs（图1）。这将使我们能够更容易地探测氧化催化过程中这些聚甲醛和水之间的重要相互作用。本研究小组先前使用的获取钴取代POM [(CoW5O18H)2]6-（图1）的新方法将用于获取新的{M'M5} POM，使用有机阳离子在非水溶剂中赋予溶解度(Eur。j . Inorg。化学。科学通报，2009,5240-5246)。最初的目标将是含有锰、铁或钌的{MMo5}类似物，然后将尝试将该系列扩大到{MMo5}钼酸盐。除了元素微量分析外，{M'M5}结构将通过红外光谱和单晶x射线晶体学来证实。此外，x射线吸收光谱（XAS）将用于探测溶液和固态中的结构和氧化态。虽然多核核磁共振原子对顺磁性化合物的使用可能受到限制，但EPR将提供有关阴离子自旋态的信息。线性伏安法和循环伏安法研究将建立聚甲醛的氧化还原特性，并确定它们是否具有驱动水氧化的适当电位。2. {M'M5} Lindqvist POMs中金属取代对反应性影响的理论认识。在塔拉戈纳URV Poblet小组新任命的PDRA的协助下，我们的POMs的密度泛函数理论（DFT）建模将与实验研究并行进行。这些研究将通过检查与质子和电子转移相关的能量来深入了解POM结构中存在的过渡金属如何影响与水的相互作用，并且可以通过实验测试计算出的氧化还原电位和静电电位分布。使用较小的Lindqvist POM， POM水氧化的计算建模应该更容易，但这样的系统迄今为止很少受到关注。将活性pom作为氧化还原介质掺入电解电池。该项目的最终目标是开发有效的水氧化催化剂，可用于工作电解槽中进行水分解。电解实验将由Mohamed Mamlouk博士进行，他是一名化学工程师，在燃料电池和电解槽设计和测试方面拥有丰富的经验。pom的作用是降低析氧过电位，从而提高电解过程的效率。