铂族金属纳米颗粒结构缺陷的电化学调控方法和机制及其电催化性能研究

To clearly reveal the effect of structural defects of platinum group metal nanoparticles on the electrocatalytic performance, an electrochemical method was proposed in this project to directly grow platinum group metal particles with clean surface on the conductive support so as to minimize or exclude the possible interference introduced through the preparation or transfer of the catalysts. The effects of the applied potential (constant potential, periodic potential, customized potential waveform) and preparation solution on the type (e.g., steps, dislocations and grain boundaries) and density of structural defects of platinum group metal particles will be systematically investigated. The effects of the applied potentials on the nucleation and growth, diffusion boundary layer, adsorption and desorption of ions, dissolution and re-deposition of the surface materials, and the coupling relationship between these processes will be clarified. And the stress distribution at the location with different curvature is going to be considered. The corresponding physical and chemical model of the controlling of the structural defects of platinum group metal materials will be established. The defective atoms will be accurately characterized by the spherical-aberration-corrected transmission electron microscopy and the corresponding stress distribution will be measured. The influence and the corresponding mechanism of the type and density of structural defects on the electrocatalytic activity and stability will be elucidated. The reaction mechanism will be clarified. The related research has important scientific significance in systematically revealing the new electrochemical controlling mechanism of structural defects of platinum group metal nanoparticles, and the role of structure defects in the electrocatalysis.

为清晰阐明铂族金属纳米颗粒催化剂中的结构缺陷对电催化性能的影响规律和机制，本项目提出采用电化学方法直接在导电基体表面生成清洁的铂族金属纳米颗粒，以尽可能降低或排除催化剂制备或转移过程中可能引入的干扰。系统研究外加电位（恒电位、周期性变化电位、自定义电位波形）和溶液条件对纳米颗粒的结构缺陷类型（如台阶、位错、晶界等）和密度的影响规律和作用机制，阐明外加电位对形核和生长过程、扩散边界层、离子的吸附和脱附、材料表面溶解和再沉积等过程的影响，以及这些过程间的耦合关系，并重点考虑不同曲率位置处的应力分布，建立相应的铂族金属材料结构缺陷调控的物理化学模型。采用球差校正透射电子显微镜精确表征缺陷原子并测量应力分布，阐明结构缺陷的类型和密度对电催化活性和稳定性的影响规律和作用机制，阐明反应机理。相关研究对于系统揭示铂族金属纳米颗粒结构缺陷的新型电化学调控机制及结构缺陷在电催化中所起作用具有重要科学意义。

针对铂族金属在清洁能源转换与存储(如燃料电池)等领域的重要催化应用，围绕铂族金属(如Pt、Pd)等电极材料的电化学调控及催化性能开展了深入系统的研究。系统研究了电化学调控参数(如沉积电位、沉积温度、周期性方波的频率，周期性方波修饰时间和前驱体溶液浓度等)对Pt、Pd纳米颗粒催化剂的尺寸、形貌及结构缺陷等结构特征的影响演变规律，揭示了外加电位对形核和生长过程、扩散边界层、离子的吸附和脱附、材料表面溶解和再沉积等过程的影响以及它们之间耦合关系，构建了相应的电化学调控物理化学模型，并结合电化学催化性能表征结果，揭示了电极微观表面原子结构缺陷与催化剂电催化性能的构效关系，阐明了其作用机理，为从微观层次设计和构建高性能的电催化剂提供了理论基础。在本项目基金的资助下，在Adv. Energy Mater.、Adv. Funct. Mater.、Angew. Chem. Int. Ed、Catalysts等国际期刊共发表SCI收录论文7篇(标注有基金资助)，1篇论文入选 ESI 高被引论文，申请发明专利3项，出版学术著作2本，培养博士生1名，硕士生3名，参加相关学术会议2次。