Deterministic Synthesis of Pd Nanocrystals Enclosed by High-Index Facets and Their Enhanced Activity toward Formic Acid Oxidation

• Type of Material: Article
• Authors: Maochang Liu, Emory University; Siya Zhou, Georgia Institute of Technology; Sang-Il Choi, Emory University; Younan Xia, Emory University
• Language: English
• Date: 2023-07-24
• Publisher: ACS Publications
• Publication Version: Final Published Version
• Copyright Statement: © 2023 The Authors. Co-published by University of Science and Technology of China and American Chemical Society
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): https://doi.org/10.1021%2Fprechem.3c00060
• Title of Journal or Parent Work: Precision Chemistry
• Volume: 1
• Issue: 6
• Start Page: 372
• End Page: 381
• Grant/Funding Information: This work was supported in part by a grant from the NSF (CBET-2219546) and startup funds from the Georgia Institute of Technology. As a visiting Ph.D. student from Xi’an Jiaotong University, M.L. was also partially supported by the China Scholarship Council (CSC).
• Keywords: formic acid oxidation (FAO); concave trisoctahedra; deposition; catalytic performance; kinetic control; Palladium (Pd) nanocrystals; direct formic acid fuel cells (DFAFCs); noble-metal nanocrystals; palladium; unconventional morphology; high-index facet; surface diffusion
• Research Categories: Physics, General; Engineering, Biomedical

Abstract

Noble-metal nanocrystals enclosed by high-index facets are of growing interest due to their enhanced catalytic performance in a variety of reactions. Herein, we report the deterministic synthesis of Pd nanocrystals encased by high-index facets by controlling the rate of deposition (Vdeposition) relative to that of surface diffusion (Vdiffusion). For octahedral seeds with truncated corners, a reduction rate (and thus deposition rate) faster than that of surface diffusion (i.e., Vdeposition/Vdiffusion > 1) led to the formation of concave trisoctahedra (TOH) with high-index facets. When the reduction was slowed down, in contrast, surface diffusion dominated the growth pathway. In the case of Vdeposition/Vdiffusion ≈ 1, truncated octahedra with enlarged sizes were produced. When the reduction rate was between these two extremes, we obtained concave tetrahexahedra (THH) without or with truncation. Similar growth patterns were also observed for the cuboctahedral seeds. When the Pd octahedra, concave TOH, and concave THH were tested for electrocatalyzing the formic acid oxidation (FAO) reaction, those with high-index facets were advantageous over the conventional Pd octahedra enclosed by {111} facets. This work not only contributes to the understanding of surface diffusion and its role in nanocrystal growth but also offers a general protocol for the synthesis of nanocrystals enclosed by high-index facets.