有序介孔与分级孔过渡金属磷化物的构筑及其电催化析氢性能研究

Water electrolysis is an efficient, clean route to generate hydrogen. Catalysts based on precious metals, such s platinum, have excellent catalytic performance toward hydrogen evolution reaction (HER) in water electrolysis, but they are not suitable for wide-spread practical applications due to their expense and scarcity. Transition-metal phosphides have intrinsically high catalytic activity toward HER. However, most of the reported transition-metal phosphide catalysts suffer from three main limitations, i.e., low specific surface areas, poor electrical conductivity and high mass-transfer resistance. Aimed by improving HER catalytic performance, and based on the construction of ordered mesoporous and hierarchical meso-macroporous metal phosphides, this project will explore a new strategy to prepare metal phosphide HER catalysts. We will utilize organic-inorganic, nano-casting and topological conversion techniques to convert mesoporous silica into mesoporous metal oxide, then to mesoporous metal phosphide, leading to the formation of a porous structure. Benefiting from the highly intrinsic activity toward HER of metal phosphide, the large surface area and abundant exposed active sites of mesopores, and the low charge/mass transfer resistance of macropores, we will be able to synergistically optimize the electrochemical properties of metal phosphide, mesopores and macropores, thus develop HER catalysts with large surface area and excellent charge/mass transfer performance.

电解水制氢是一种高效、清洁的制氢技术。铂等贵金属是最有效的电解水析氢催化剂，但因价格昂贵不适合大规模使用。因此，发展高效的非贵金属析氢催化剂对实现水电解制氢技术的大规模应用具有重要意义。过渡金属磷化物具有较高的本征析氢催化活性，但目前其催化性能与铂相比仍有一定差距。限制其催化性能的主要因素为比表面小、电导率低、传质性能差。本项目以提高水电解析氢催化性能为导向，以金属磷化物的有序介孔和分级孔结构的构筑为基础，探索一条制备过渡金属磷化物析氢催化剂的新途径。研究中借助无机-有机自组装、纳米浇筑和原位拓扑转变技术实现介孔二氧化硅→介孔金属氧化物→介孔金属磷化物的转变，进而构建金属磷化物的多孔结构。利用金属磷化物的高本征催化活性、介孔材料的大比表面与充分暴露的活性位、大孔材料的传质传荷特性实现金属磷化物、介孔、大孔三者的电化学协同优化，发展兼具高活性表面积和优异传荷传质性能的析氢催化剂。

本项目借助无机-有机自组装、纳米浇筑、自牺牲模板法和原位拓扑转变技术，开发了几种多孔过渡金属磷化物的可控制备技术，包括有序介孔金属磷化物、三维有序大孔金属磷化物、多级有序孔金属磷化物。揭示了多孔金属磷化物结构形成过程中的物理化学过程及相关机制。对所制备的过渡金属磷化物的电催化析氢性能进行了系统考察，建立了多孔结构与电催化性能之间的内在关系及影响规律，揭示了催化反应机理。利用金属磷化物的高本征催化活性、介孔材料的大比表面与充分暴露的活性位、大孔材料的传质传荷特性实现金属磷化物、介孔、大孔三者的电化学协同优化，发展了兼具高活性表面积和优异传荷传质性能的析氢催化剂。圆满完成了研究目标。本项目的研究成果对发展介孔材料可控制备技术、深入认识析氢催化反应机理以及开发高效的析氢催化剂提供了理论和实验基础。