Pt基和Pd基催化剂催化甲酸电化学氧化机制的理论研究

Among various types of fuel cells, direct formic acid fuel cells (DFAFCs) are considered as the most promising power source that can offer the most extensive application in the near future. The electro-oxidation efficiency of formic acid is a key factor in determining the proerty of this class of fuel cells. Searching for the catalysts that are of excellent catalytic activity and improved tolerance towards CO-poisoning is becoming a challenging issue in the study of DFAFCs. Pt and Pd mono-mental catalysts as well as Pt- and Pd-based bimetal catalysts are found to be the most effective catalysts towards the electro-oxidation activity of formic acid. However, the relevant mechanism behind the phenomenon remains unclear, and some experimental observations are still not well understood. This proposal aims to elucidate the molecular mechanism of formic acid electro-oxidation promoted by a series of Pt- and Pd-based catalysts based on the results of quantum chemistry calculations. Our studies will pay substantial attentions on the following several aspects: (i) the mechanism details of formic acid oxidation along various possible pathways, (ii) the thermodynamic and dynamical properties of the formic acid oxidation, (iii) the relative stability of various activate intermediates and transition states involved along each pathway, (iv) the influence of applied electrode potentials on the reactivity, (v) the intrinsic mechanism of the synergetic effect of Pt-, and Pd-based bimetallic catalysts, (vi) key factors controlling the catalytic activity of Pt- and Pd-based catalysts, and the new and reasonable theoretical model describing the electro-oxidation of formic acid. We believe that the theoretical results would provide valuable guidance and assist for the rational design of efficient Pt- and Pd-based electrocatalysts of DFAFCs.

直接甲酸燃料电池（DFAFCs）被认为是最有应用前景的新型能源系统,甲酸的电化学氧化效率是决定该类电池性能的关键因素.寻找对甲酸氧化催化活性好、抗中毒能力强的催化剂是DFAFCs研究中迫切需要解决的关键科学问题. 铂基和钯基催化剂被发现是甲酸电化学氧化最有效的阳极催化剂，但有关的分子机理尚不十分清楚,一些实验现象尚不能得以合理解释.本项目着眼于在原子分子水平上理解铂基和钯基催化剂催化甲酸电化学氧化的微观机理，用量子化学方法开展系统的理论研究,探讨甲酸电化学氧化的各种反应路径，分析反应的热力学和动力学性质,识别甲酸氧化过程中各种活性中间体和过渡态结构的相对稳定性,研究外加电位对反应性能的影响，弄清铂基和钯基双金属催化剂催化增效机制的微观本质,掌握控制催化活性的关键因素, 完善甲酸电化学氧化的理论模型，从而为DFAFCs新型阳极催化剂的开发和设计奠定一定的理论基础、提供一定的理论指导.

直接甲酸燃料电池被认为是最有应用前景的新型能源系统,甲酸的电化学氧化效率是决定该类电池性能的关键因素.寻找对甲酸氧化催化活性好、抗中毒能力强的催化剂是DFAFCs研究中迫切需要解决的关键科学问题. 贵金属催化剂，包括铂、钯基催化剂，被发现是甲酸电化学氧化最有效的催化剂，但有关的分子机理尚不十分清楚,一些实验现象尚不能得以合理解释.本项目着眼于在原子分子水平上理解贵金属催化剂催化甲酸化学氧化的微观机理，用量子化学方法开展了系统的理论研究探讨了甲酸的一系列表面催化反应和均相催化反应，建立、完善了甲酸氧化的各类理论模型，探讨了甲酸单体、二聚体催化氧化的微观机理，分析了反应的热力学和动力学性质,识别了甲酸氧化过程中各种活性中间体和过渡态的相对稳定性,弄清了贵金属催化剂表面催化和均相催化的微观本质，分析了双金属催化剂增效机制的分子机理,掌握了控制催化活性的关键因素. 特别是我们通过系列的研究发现，多数催化体系中甲酸氧化过程涉及分子间的长距离氢迁移,甲酸分子一方面作为反应物提供氢源,另一方面作为氢传输的载体,甲酸二聚体通过三中心四电子键稳定过渡态结构, 实现甲酸的表面催化脱氢和均相催化氧化.研究课题取得了一系列创新性研究成果，为直接甲酸燃料电池新型催化剂的开发和设计奠定一定的理论基础、提供了有价值的理论指导.