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Self‐assembly of Atomically Dispersed Ag Catalysts on Polyhedral Co 3 O 4 at Elevated Temperatures: A Top‐Down Nanofabrication of High‐Loading Atomically Dispersed Catalysts
Author(s) -
Huang Zhiwei,
Zhang Jie,
Du Yuyao,
Zhang Ying,
Wu Xiaomin,
Jing Guohua
Publication year - 2020
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201901712
Subject(s) - catalysis , xanes , extended x ray absorption fine structure , noble metal , materials science , reactivity (psychology) , nanoparticle , metal , oxide , absorption (acoustics) , absorption spectroscopy , crystallography , nanotechnology , chemistry , spectral line , organic chemistry , medicine , physics , alternative medicine , pathology , quantum mechanics , astronomy , composite material , metallurgy
Catalysts based on atomically dispersed noble metal catalysts have attracted considerable attention due to their enhanced reactivity and selectivity. However, to prevent the formation of metal nanoparticles and to keep the dispersity of isolated single atoms on surface, the loading concentration of the noble metal must be kept low (usually below 0.5 %). Here, we report a self‐assembly approach for synthesizing a stable atomically dispersed silver‐cobalt oxide catalyst on polyhedral Co 3 O 4 nanoparticles containing Ag up to 10 wt % at elevated temperature. The sample‐averaged extended X‐ray absorption fine structure (EXAFS) analysis revealed the presence of highly dispersed Ag species along with small Ag clusters. The coordinatively unsaturated Co 3+ centers present on the {110} facets of the Co 3 O 4 surface were shown to be crucial for anchoring catalytically active single Ag atoms. Control experiments showed that polyhedral Co 3 O 4 was more effective than Co 3 O 4 ‐cube and Co 3 O 4 ‐octahedron at anchoring Ag atoms. The oxidized nature of the atomically dispersed Ag sites was revealed by X‐ray absorption near‐edge structure (XANES) Ag−L 3 ‐edge spectra. From the H 2 ‐temperature programmed reduction and CO oxidation test, it was discovered that downsizing catalytically active components from nanocrystals to single atoms not only enhanced the catalytic activity, but also endowed single‐atom catalysts with exceptional oxygen activation ability at low temperature.