碳酰肼电氧化反应用高活性金属催化剂的理性设计与机理研究

As the limitation of hydrogen storage and filling, the developing of polymer electrolyte membrane fuel cells based on novel fuels have attracted great attention. Direct carbohydrazide fuel cells are believed to have great potential due to their significant advantages, such as high theoretical electromotive force and energy density, as well as easiness of storage and transport. However, the catalytic activities of current meal catalysts towards carbohydrazide oxidation reaction are quite low, and the relationship between catalysts structure and performance is unclear. To understand the mechanism of carbohydrazide electro-oxidation reaction and improve the activity of metal catalysts, this work proposes to investigate the relationship between electronic properties and catalytic performance of varied metal catalysts. The proposal aims to: 1) investigate the interaction between metal surfaces and reaction substrates by density functional theory calculation, which includes carbohydrazide molecule, intermediates and products of the reaction, and the relationship between electronic properties of metal and adsorption of reaction substrates on metal surface, 2) prepare corresponding metal catalysts and characterize the catalytic performance, and investigate the relationship between the reaction substrates adsorption and the catalytic activity to establish volcano plots of metal catalysts; 3) provide guidance information to design novel catalysts according to the volcano plots to obtain improved catalytic activity. The proposed studies will not only provide fundamental understanding of the reaction mechanism of carbohydrazide electro-oxidation reaction on metal catalysts, but also open up exciting opportunities to design more effective electro-catalysts.

针对目前氢气储运和加注受限的问题，发展基于新型燃料的聚合物膜燃料电池受到广泛关注。直接碳酰肼燃料电池以其理论电动势和能量密度高、燃料便于储运等优点而具有较大的发展潜力。但是碳酰肼电氧化反应历程复杂，现有的催化剂活性较低，且对其构效关系缺乏系统认识。本项目拟采用“金属的电子性质-反应底物的吸附-催化活性”的研究思路，通过理论计算分析不同金属对碳酰肼氧化过程中反应底物的吸附行为，阐释金属电子性质对吸附的调控机制，解析碳酰肼电氧化反应历程，获得反应过程的关键反应底物；在此基础上考察不同金属催化剂对碳酰肼电氧化反应的催化活性，建立反应底物吸附与催化活性之间的火山型关系，获得碳酰肼电氧化反应的描述符；指导催化剂设计与制备，获得高活性催化剂材料，为碳酰肼电氧化反应催化剂的理性设计奠定理论与实验基础。

针对碳酰肼电氧化反应历程复杂、现有催化剂活性较低的问题，申请人遵循“金属的电子性质-反应底物的吸附-催化活性”的研究思路，采用理论计算和实验研究相结合的研究方法，通过考察催化剂的载体效应和溶剂效应，分析了催化剂与碳酰肼之间的相互作用，解析了碳酰肼电氧化反应的影响因素，研究了碳酰肼电氧化反应历程。取得如下主要结果：.（1）建立并发展了考察催化剂载体效应的团簇模型，并用于指导过渡金属单原子材料和含不同官能团碳纳米管电催化剂的设计；.（2）在上述研究工作的基础上，开展了碳酰肼电氧化催化剂的理性设计工作，获得了碳酰肼电氧化反应的“火山型”关系图，并用于指导基于钯镍合金的碳酰肼电氧化反应高效催化剂；.（3）通过密度泛函计算和原位红外光谱解析等方法，研究了碳酰肼电氧化反应历程，提出了可能的反应机制。