Porous Au-rich Nanoparticles for Catalytic Applications

多金属纳米颗粒(NPs)的脱合金化是制备高效、耐用催化剂的重要途径，可用于甲醇氧化反应、氧气还原反应等多相和电化学反应。特别是，多孔纳米粒子具有较高的比表面积与体积比，并且能够调节其孔限制和表面曲率，从而可能导致反应动力学的改善。原始纳米合金的粒度、化学成分以及脱合金化条件(电解液、电位、温度等)。在设计具有先进功能的纳米多孔贵金属富金属纳米粒子方面发挥着非常关键的作用。在脱合金化过程中，细小的双金属纳米颗粒形成核壳结构，而宏观合金化薄膜则形成海绵状的孔结构。基本问题是形成纳米多孔纳米颗粒的临界颗粒尺寸是多少，以及哪些去合金化参数控制了纳米多孔纳米颗粒内部的晶格应变和化学分布。此外，目前还不清楚为什么与平坦的合金化表面相比，通过减小颗粒尺寸来使溶解电势向更高的值移动。所有这些基本问题都将在研究单位内进行调查。我们的目标是设计具有可控制的粒度、孔径和非贵金属含量的脱合金型富Au纳米颗粒。该脱合金型纳米颗粒是从Ag-Au和Cu-Au纳米合金中脱合成的。通过施加不同的(电)化学脱合金化条件，分析了脱合金基NPs中Au和Ag/Cu原子的应变和化学分布，阐明了多孔富Au纳米颗粒的形成机理。本文所提出的脱合金型富Au纳米粒子的综合研究，将对促进有机小分子氧化催化剂的发展做出重要贡献，并有望促进其应用。

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.