Porous Au-rich Nanoparticles for Catalytic Applications

多金属纳米颗粒的脱合金化是制备高活性、高耐久性催化剂的一条重要途径，可用于甲醇氧化、氧气还原等多相电化学反应。特别是，多孔纳米颗粒显示出高的表面积与体积比，并能够调整其孔限制和表面曲率，这可能导致反应动力学的改善。原始纳米合金的颗粒直径和化学组成以及去合金化条件（电解质、电势、温度等）是纳米合金化的最佳条件。在设计具有高级功能的纳米多孔富贵金属纳米颗粒中起着非常关键的作用。在脱合金过程中，小的纳米颗粒形成核壳结构，而宏观合金膜则形成海绵状孔结构。基本的问题出现了什么样的临界颗粒尺寸形成的纳米多孔纳米粒子是和哪些去合金化参数控制的晶格应变和化学分布内的纳米多孔纳米粒子。此外，迄今为止尚不清楚为什么与平坦的合金化表面相比，通过减小颗粒尺寸，溶解电位偏移到更高的值。所有这些基本问题都将在研究单位内进行调查。我们的目标是设计脱合金的富金纳米颗粒，通过从Ag-Au和Cu-Au纳米合金中脱合金化Ag/Cu来制备具有受控的颗粒尺寸、孔径和较少贵金属含量的脱合金富金纳米颗粒。我们将阐明多孔富Au纳米颗粒的形成机制作为原始合金纳米颗粒的粒度和化学组成的函数，并将通过应用不同的（电）化学脱合金条件来分析脱合金Au基纳米颗粒内部的应变和Au和Ag/Cu原子的化学分布。因此，对脱合金富金纳米粒子的综合研究将为促进有机小分子氧化催化剂的发展做出重要贡献，并有望推动其应用。

Dealloying of multi-metallic nanoparticles (NPs) has emerged as promising synthetic route to prepare highly active and durable catalysts for heterogeneous and electrochemical reactions like methanol oxidation reaction and oxygen reduction reaction. In particular, porous NPs show high surface area-to-volume ratios and enable to tune its pore confinement and surface curvature which might result in an improvement of the reaction kinetics. The particle diameter and chemical composition of the pristine nano-alloys as well as the dealloying conditions (electrolyte, potential, temperature, etc.) play a very critical role in the design of nanoporous noble metal-rich NPs with advanced functionality. Small bimetallic NPs form core-shell structures during the dealloying process, while for macroscopic alloyed films sponge-like pore structure is produced. The fundamental questions arise what the critical particle size for the formation of nanoporous NPs is and which dealloying parameters controll the lattice strain and chemical distribution inside the nanoporous NPs. In addition, it is not clear to date why the dissolution potential is shifted to higher values by decreasing particle size compared to flat alloyed surfaces. All these fundamental questions will be investigated within the research unit. Our goal is to design dealloyed Au-rich NPs with controlled particle size, pore size and content of less noble metal prepared by dealloying of Ag/Cu from Ag-Au and Cu-Au nano-alloys. We will elucidate the formation mechanism of the porous Au-rich NPs as the function of the particle size and chemical composition of the pristine alloy NPs and will analyze the strain and the chemical distribution of Au and Ag/Cu atoms inside the dealloyed Au-based NPs by applying different (electro)chemical dealloying conditions. Here, the proposed comprehensive study of dealloyed Au-rich NPs will make an important contribution to promote oxidation catalysts for small organic molecules and hopefully boost their application.