高分散Pd位点调控AuCu@PdAu核壳合金催化剂H2O2直接合成性能研究

H2和O2高选择性直接合成H2O2具有重要的学术和工业意义。针对H2O2高选择性调控机制不明、催化剂无法兼顾Pd原子高分散和高效利用的难题，本项目提出，通过定向置换AuCu合金纳米颗粒表面Cu原子，制备出富含高分散Pd位点的AuCu@PdAu核壳结构催化剂，以同时提高H2O2选择性、活性和Pd原子利用效率。通过研究Pd/Cu原子置换过程，阐明AuCu合金纳米颗粒表面结构和置换反应动力学参数对高分散Pd位点形成和结构的影响机制。拟采用动力学分析、原位表征和量化计算等方法系统研究单原子、双原子/三原子小团簇等高分散Pd位点结构对H2O2直接合成主反应、副反应性能的影响规律，揭示动力学调控机制；明确H2O2直接合成基元反应路径，揭示O2非解离活化、OOH生成对H2O2选择性生成的调控机制，认识H2O2直接合成反应机理，建立构-效关系，为高性能和低成本Pd基合金催化剂的开发提供理论基础。

The highly selective synthesis of H2O2 directly from H2 and O2 is of vital significance for fundamental research and industrial application. Towards the uncertain regulation mechanism of high selectivity of H2O2 formation and the problem of Pd based catalysts without simultaneous achievement of high dispersion and high utilization of Pd atoms, this project is proposed to develop a core-shell structured AuCu@PdAu alloy catalyst with rich highly dispersed Pd sites at surface through the Pd/Cu galvanic replacement reaction on the AuCu alloy nanoparticle. The galvanic replacement process of Pd/Cu will be studied to clarify the mechanism for the influence of surface structure of AuCu alloy nanoparticles and replacement kinetics on the formation and structure of highly dispersed Pd sites. The analysis of reaction kinetics, in situ characterization and DFT calculation will be used to systematically studied the influence of the Pd sites with Pd monomers and the small ensembles with dimers/trimers on the performance of H2O2 formation, H2O formation, H2O2 decomposition and hydrogenation, and reveal the kinetic regulation mechanism. The elementary reaction pathways for direct synthesis of H2O2 will also be studied to understand the regulation mechanism of non-dissociative activation of O2 and OOH generation on the selective formation of H2O2 and the reaction mechanism of direct synthesis of H2O2. Based on these above results, the relationship between the structure of AuCu@PdAu catalyst and performance will be established. The findings of this project will provide the theoretical basis for the development of high-performance and low-cost Pd based alloy catalysts.