基于非贵金属催化剂燃料电池空气电极研究

Fuel cells, the devices that directly convert chemical energy to electrical energy, are extremely efficient at extracting energy from fuels. Fuel cells are known as the fourth generation of generators, following hydraulic, thermal, and nuclear power generation. They are a viable solution for backup power for tomorrow. Nitrogen-doped carbon (NC) has been recognized as a promising cathode catalyst due to their acceptable ORR activity, excellent chemical stability, and low cost. However, its catalytic activity is still at a low level compared to Pt catalysts due to their intrinsic property, low electron conductivity, and insufficient active sites. In this project, we develop a novel strategy to enhance the catalytic activity of NC catalysts via regulating the active site, increasing electron and proton transport channels of the NC catalysts. Secondly, we plan to explore the rule that governs the interaction between the two-phase flow and the electrochemical reaction in the micro-channel of air electrode catalyst layer, which has been markedly thickened owing to NC catalyst utility. Finally, we hope to enhance the reaction efficiency of the air electrode by means of the ordering the pore distribution for gas and water transport.

燃料电池（FCs）是将燃料中的化学能直接转换为电能的一种转换装置，以其高效、洁净、兼容可再生能源技术等特点，被认为是后石油时代解决移动高性能动力电池的理想方案之一。氮掺杂碳催化剂（NC）表现出较高的氧还原（ORR）催化活性，且具有成本低、寿命长和环境友好等特点，被认为有可能替代铂基催化剂成为新一代燃料电池催化剂。但是，NC催化剂的催化活性与Pt基催化剂相比仍有明显差距。如何大幅度提高NC催化剂的催化活性、改善催化层内全局的传质效率是实现燃料电池催化剂NC化的关键。本申请提出“基于非贵金属催化剂燃料电池空气电极研究”，通过对非贵金属催化剂形貌、反应活性位、电子运输通道的构建与模拟，以提高非贵金属催化剂的活性位和增加体积密度；通过探索燃料电池膜电极中电化学反应与气液两相流、电子、质子传递耦合规律，以有序化膜电极结构，提高膜电极反应与传质效率。

针对非贵金属催化剂燃料电池空气电极催化活性差、活性位密度低、传质效率不高等问题，本课题通过实验探究1）发明了盐重结晶固型法宏量制备高性能N-C催化剂的新方法；2）首次证实Fe-N-C类催化剂在碳层包覆Fe/Fe3C纳米粒子的邻近位置存在Fe-Nx活性位点，成功地解释Fe-N-C催化剂的高活性来源；3）提出并确认了反式尖晶石结构中八面体中心不同原子导致的“异化效应”；4）开发了一种全新的基于气液界面反应和气液相转变反应的“高温相变反应法”制备高效N-C催化剂；5）设计了一种两部假象转化法来解决碳材料在高温合成过程中存在的易烧结和结构坍塌问题。本课题通过各种方法制备不同掺杂情况、不同结构的非贵金属氧还原催化剂，并通过理论计算研究了不同因素对氧还原催化剂活性的影响，揭示了氧还原反应的活性来源，设计并合成了一系列高活性的非贵金属氧还原催化剂。