Department of Chemistry and Biochemistry and ‡Department of Chemical Engineering, University of South Carolina , Columbia, South Carolina 29208, United States.
Nano Lett. 2016 Nov 9;16(11):7248-7253. doi: 10.1021/acs.nanolett.6b03685. Epub 2016 Oct 4.
Percolation dealloying of multimetallic alloys entangles the selective dissolution of the less-noble elements with nanoscale restructuring of the more-noble components, resulting in the formation of spongelike, nanoporous architectures with a unique set of structural characteristics highly desirable for heterogeneous catalysis. Although the dealloyed nanoporous materials are compositionally dominated by the more-noble elements, they inevitably contain residual less-noble elements that cannot be completely removed through the percolation dealloying process. How to employ the less-noble elements to rationally guide the structural evolution and optimize the catalytic performances of the dealloyed noble metal nanocatalysts still remains largely unexplored. Here, we have discovered that incorporation of Ag into Au-Cu binary alloy nanoparticles substantially enhances the Cu leaching kinetics while effectively suppressing the ligament coarsening during the nanoporosity-evolving percolation dealloying of the alloy nanoparticles. The controlled coleaching of Ag and Cu from Au-Ag-Cu ternary alloy nanoparticles provides a unique way to optimize both the surface area-to-mass ratios and specific activities of the dealloyed nanosponge particles for the electrocatalytic oxidation of alcohols. The residual Ag in the fully dealloyed nanosponge particles plays crucial roles in stabilizing the surface active sites and maintaining the nanoporous architectures during the electrocatalytic reactions, thereby greatly enhancing the durability of the electrocatalysts. The insights gained from this work shed light on the underlying roles of residual less-noble elements that are crucial to the rational optimization of electrocatalysis on noble-metal nanostructures.
多金属合金的渗流脱合金将较不活泼元素的选择性溶解与较活泼成分的纳米尺度重构纠缠在一起，形成具有独特结构特征的海绵状纳米多孔结构，非常适合多相催化。虽然脱合金纳米多孔材料在组成上主要由较活泼的元素主导，但它们不可避免地含有残留的较不活泼元素，这些元素无法通过渗流脱合金过程完全去除。如何利用较不活泼的元素合理引导结构演变并优化脱合金贵金属纳米催化剂的催化性能，在很大程度上仍未得到探索。在这里，我们发现将 Ag 掺入 Au-Cu 二元合金纳米颗粒中，在有效地抑制合金纳米颗粒纳米多孔性演变渗流脱合金过程中连接体粗化的同时，显著提高了 Cu 的浸出动力学。从 Au-Ag-Cu 三元合金纳米颗粒中受控共浸出 Ag 和 Cu，为优化脱合金纳米海绵颗粒的比表面积与质量比以及比活性，提供了一种独特的方法，以用于醇的电催化氧化。在完全脱合金的纳米海绵颗粒中残留的 Ag 在电催化反应过程中稳定表面活性位和维持纳米多孔结构方面发挥着至关重要的作用，从而极大地提高了电催化剂的耐久性。这项工作的见解揭示了残留较不活泼元素在贵金属纳米结构电催化的合理优化中所起的关键作用。
