Su Keying, Zhang Huaifang, Qian Shiyun, Li Jiatian, Zhu Jiawei, Tang Yawen, Qiu Xiaoyu
Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
Department of Chemical Engineering, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China.
ACS Nano. 2021 Mar 23;15(3):5178-5188. doi: 10.1021/acsnano.0c10376. Epub 2021 Feb 15.
Simultaneously engineering the size and surface crystal facets of bimetallic core-shell nanocrystals offers an effective route to not only reduce the extravagance of innermost core metal and maximize the utilization efficiency of shell atoms but also strengthen the core-to-shell interaction ligand and/or strain effects. Herein, we systematically study the architecture transition and crystal facet engineering at the atomic level on the surface of sub-5 nm Pd(111) tetrahedrons (Ths), aimed at embodying how the variations in the local facet and shape of a sub-10 nm core-shell structure affect its surface geometrical properties and electronic structures. Specifically, surface atomic replication is predominant when the shell metal deposits less than five atomic layers, thus forming a series of Pd@M (M = Pt, Ru, and Rh) core-shell Ths enclosed by (111) facets (∼6.8 nm), while over five atomic layers, spontaneous facets tropism of each metal is predominant, where Pt atoms still follow -(111) packing, Ru atoms select -phase stacking, and Rh atoms choose -(100) crystallization, respectively. In particular, Pt atoms take a seamless geometrical transformation from Pd@Pt Ths into Pd@Pt truncated octahedrons (TOhs, ∼7.6 nm). As a proof-of-concept application, such sub-10 nm core-shell architectures with Pt skin show a component-dependent relationship toward oxygen reduction reaction (ORR), where the catalytic activity follows the order of Pd@Pt(111) TOhs ( = 0.916 V, 1.632 A mg) > Pd@Pt(111) Ths > Pt black. Meanwhile the Ru skin show a facet-dependent relationship toward acidic hydrogen evolution reaction (HER) where the catalytic activity follows the order of Pd@Ru(111) Ths > Pd@Ru() Ths > Pd Ths.
同时对双金属核壳纳米晶体的尺寸和表面晶面进行工程设计，不仅为减少最内层核心金属的浪费、最大化壳层原子的利用效率提供了一条有效途径，而且还能增强核壳相互作用（配体和/或应变效应）。在此，我们系统地研究了亚5纳米钯（111）四面体（Ths）表面原子水平上的结构转变和晶面工程，旨在体现亚10纳米核壳结构的局部晶面和形状变化如何影响其表面几何性质和电子结构。具体而言，当壳层金属沉积少于五个原子层时，表面原子复制占主导，从而形成一系列由（111）晶面包围（约6.8纳米）的Pd@M（M = Pt、Ru和Rh）核壳Ths，而超过五个原子层时，每种金属的自发晶面取向占主导，其中Pt原子仍遵循-（111）堆积，Ru原子选择-相堆积，Rh原子分别选择-（100）结晶。特别地，Pt原子从Pd@Pt Ths到Pd@Pt截顶八面体（TOhs，约7.9纳米）发生无缝几何转变。作为概念验证应用，这种具有Pt壳层的亚10纳米核壳结构对氧还原反应（ORR）呈现出成分依赖关系，其中催化活性遵循Pd@Pt(111) TOhs（= 0.916 V，1.632 A mg）> Pd@Pt(111) Ths > Pt黑的顺序。同时，Ru壳层对酸性析氢反应（HER）呈现出晶面依赖关系，其中催化活性遵循Pd@Ru(111) Ths > Pd@Ru() Ths > Pd Ths的顺序。
