同步辐射研究3d过渡金属掺杂1T-MX2(M=Mo/W;X=S/Se)纳米片电催化机理

Exploring the inexpensive, efficient and stable hydrogen evolution catalyst is the key to promote electrocatalytic hydrogen evolution reaction (HER). The two-dimensional nanostructures of layered transition metal chalcogenide MX2 (M =Mo/W;X=S/Se) are widely concerned due to their excellent hydrogen evolution activity in acidic environments. However, the sluggish HER kinetics in alkaline solution is a bottleneck in the development of such materials. In this project, stable metallic 1T-MX2 nanosheets were used as the research object, 3d transition metal doping can regulate the electrochemical kinetics of 1T-MX2 in alkaline conditions. Using in-situ synchrotron radiation X-ray absorption fine spectroscopy (XAFS), the dynamic processes of HER was real-time monitored to explore the evolution of electronic and local atomic structures in catalysts under operando conditions, and disclose the interactions between catalytic center and ambient coordination environment. Combined with the first-principle calculation, the effect of the transition metal doping on the electronic structure of 1T-MX2 as well as the dissociation of surface water, hydrogen atoms, hydroxyl and other intermediate species adsorption/desorption process modulation and synergistic effect are studied. We expect to reveal the evolution rules and micromechanisms of electrocatalytic HER in alkaline condition by using XAFS and theoretical calculation. The project will provide experimental basis and theoretical guidance for the further design of efficient and stable hydrogen evolution electrocatalyst.

探索廉价、高效、稳定的析氢电催化剂是推动电解水制氢的关键。层状过渡金属硫属化合物MX2 (M=Mo/W;X=S/Se) 二维纳米结构因其在酸性环境下优异的析氢活性而受到广泛关注，然而碱性条件下迟缓的动力学过程是这类材料发展的瓶颈。本项目拟以稳定的金属相1T-MX2纳米片为研究对象，通过3d过渡金属掺杂来调控碱性条件下的电化学动力学过程，利用原位同步辐射X射线吸收谱学技术在线监测催化过程中催化剂的局域原子和电子结构变化，以及活性中心与周围化学环境的相互作用；结合第一性原理计算，揭示3d过渡金属掺杂对1T-MX2的电子结构的调控作用，以及对表面水的解离、氢原子、氢氧根等中间物种的吸附/脱附等过程调制和协同效应，总结出碱性条件下3d过渡金属掺杂1T-MX2电催化析氢的微观机制。项目的开展将为进一步设计高效稳定的析氢电催化剂提供实验依据和理论指导。

在国家自然科学基金委青年基金项目（批准号：11705205）的资助下，负责人基本完成预定研究目标。在廉价、高效非贵金属催化体系探索方面，发展了一系列结构明确的二维团簇催化剂，并实现了可控制备。在材料表征方面，建立了同步辐射技术和球差校正透射电镜相结合的方法来解析催化剂的局域原子/电子结构。在作用机制理解方面，通过理论和实验结合，阐明了催化反应路径和分子活化机制。同时，还通过本项目的资助，在新型催化体系探索方面，得到了多孔NU1000限域的一系列单原子过渡金属取代的Anderson多酸团簇结构，硫化出相应的硫化钼团簇结构，开发了这些材料的电催化析氢和气相催化方面的应用。