界面间低配位数铁镍双金属对的构筑及其析氧电催化协同机制探究

铁-镍离子中心对析氧反应（电解水速控过程）的协同催化效应源自二者对不同亚稳态中间氧物种的选择性吸附。当前析氧电催化剂以尺寸较大的非负载型双金属化合物为主，难以获得低配位数金属位点，活性提升有限；且两金属中心在原子尺度上均匀互混，不便分别调控其局域电子结构，构效关系不明。本项目拟合成类“异质结”复合物，使铁-镍离子分属两相，一为分散相，尺寸可小至零维，以获得低配位数铁（镍）金属中心，另一为载体相，维度较高，比表面积大，可稳定分散相，两相通过氧桥相接，共筑界面间低配位数、高稳定性铁-镍双金属对；通过分别调控两相阴阳离子组成、尺寸及表面性质，以调节界面间双金属对的组成和配位数，分别优化各金属中心对不同价态氧物种的选择性吸附，探究铁镍离子局域电子结构与其电化学性能的映射关系以及协同催化规律。项目将铁镍中心“介观上一分为二，微观上分而不独”，立足界面催化，将为研发析氧电催化剂提供新思路。

The synergistic catalytic effect of Fe3+-Ni2+-based bimetal compounds towards the kinetically sluggish oxygen evolution reaction (OER) during the water splitting process originates from their selective adsorption towards the metastable intermediate oxygen species. Nevertheless, the current bimetal compounds for OER electrocatalysis usually suffer from relatively large dimension which consequently could not favor the occurrence of those highly active unsaturated metal sites; and as the two metal sites are mixed homogeneously with each other at atomic scale, it is impossible to achieve separate control over the local electronic structure of each individual metal center. In this project, various iron-group-element-based binary composites with hierarchical structures and multidimensions would be designed to construct highly active interfacial Fe3+-Ni2+ bimetal centers. Such a composite would be endowed with the configuration of the classical heterojunction where one component with ultrafine size would be immobilized on the surface of another support-like solid with relatively large dimension and high specific surface area, and the cation pair, i.e., Fe3+ and Ni2+, will be located separately in these two interfaced solids, forming highly unsaturated Fe3+-Ni2+ bimetal centers with remarkable stability. Moreover, each components in such binary composites could be manipulated individually in terms of their composition, size and surface property so as to optimize the local electronic structure of the relevant metal center for selective adsorption of various intermediate metastable oxygen species during the OER process. Furthermore, interfacial bimetal pairs with various degrees of saturation and compositions will be designed, and their interaction in various circumstances would be examined to understand the contribution of each metal center to the resulting electrochemical behaviors and catalytic performances. On this basis, the interaction between Fe3+ and Ni2+ and their synergistic catalytic mechanism towards OER would be clarified, which will lead to the rational design of highly active interfacial Fe3+-Ni2+ bimetal centers with low coordination number and high density. This project will lead to an alternative configuration for high-performance OER electrocatalyst where Fe3+ and Ni2+ cations on the one hand are spatially separated for efficient manipulation of each metal center and on the other hand they could interact with each other chemically through an intimate solid-solid interface.