高效界面双功能复合电催化剂的理性设计、工程组装及相关基础科学问题研究

The usage of the Pt catalyst poses a great challenge to the development of fuel cell technology; therefore, it is urgent to explore novel cheap electrocatalysts. This proposal is to develop the bifunctional interface based electrocatalysts by depositing transition metal(TM) nanoparticles on home-made 2D nitrogen-doped carbon supports. The interfacial features and its activating mechanism are then discussed for the model reactions including the oxygen reduction reaction, methanol oxidation reaction and hydrogen evolution reaction. Two electrochemical methods are used to study the electrocatalysis. First, electrochemical nanocollision is applied to study the bifunctional mechanism. By considering electronic/geometric effects, the synergistic effect is clarified for the TM/CN-doped composite electrocatalysts. Second, scanning electrochemical microscopy is used to recognize the adsorbed intermediate species and measure their coverage, from which the mechanism and intrinsic activity can be well addressed. Finally, electrochemical nanocollision is further used to explore the particulate of Pt/C-Nafion in the electrode ink. Its movement, transfer and structure can be deduced thereafter, which are of great importance for developing high-performance electrode. In summary, this project will shed light on the rational design of the bifunctional interface electrocatalysts and novel electrode structures for fuel cells.

贵金属催化剂大量使用是阻碍燃料电池技术发展的主要瓶颈，亟需探索廉价高效电催化剂。本项目以前期制备二维氮杂碳材料为载体，通过选控沉积过渡金属纳米粒子，构筑高效界面邻位双功能活性中心复合电催化剂；以氧还原、甲醇氧化、析氢等模型反应探讨界面特征对反应的活化调控机制，为发展高效界面电催化剂提供理论指导及组装策略；采用纳米碰撞电化学研究界面双功能催化促进机制，结合电子/几何效应，揭示复合催化剂协同效应具体内涵；采用扫描电化学显微镜研究中间吸附物种类型及覆盖度，揭示界面双功能催化反应机理及本征活性；采用纳米碰撞电化学探索电极浆液中团聚体颗粒结构及行为，为揭示电极成型过程非均匀结构演化规律、开发新型高效电极结构提供支撑。本项目在发展新型电化学表征方法，丰富界面电催化剂选控制备科学，深化协同效应认知方面开展工作，成果将为探索新型催化剂体系和电极结构提供理论指导和开发思路，兼具理论意义和应用价值。

本项目发展了二维氮杂碳材料制备方法，通过开展条件实验，优化了制备参数，制备了一系列具有高比表面积的二维氮杂碳材料；系统研究碳材料组成与结构信息，结合电催化反应（包括氧还原反应、质子还原反应、钒电对转化反应、溴电对转化反应等）活性信息，揭示了电化学行为与电催化反应活性位点的化学本质与构效关系；采用扫描电化学显微镜、纳米碰撞电化学等方法研究了质子还原反应与氧还原反应机制；另外，还开展了二氧化碳还原反应、光解水制氢反应等能源化学相关研究工作。