Nanograin-Boundary-Abundant Cu 2 O-Cu Nanocubes with High C 2+ Selectivity and Good Stability during Electrochemical CO 2 Reduction at a Current Density of 500 mA/cm 2

• Published in: ACS nano 2023-07, Vol.17 (13), p.12884-12894
• Main Authors: Wu, Qiqi, Du, Ruian, Wang, Peng, Waterhouse, Geoffrey I N, Li, Jia, Qiu, Yongcai, Yan, Keyou, Zhao, Yun, Zhao, Wei-Wei, Tsai, Hsin-Jung, Chen, Meng-Cheng, Hung, Sung-Fu, Wang, Xue, Chen, Guangxu
• Format: Article
• Language: English
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.3c04951

Surface and interface engineering, especially the creation of abundant Cu /Cu interfaces and nanograin boundaries, is known to facilitate C production during electrochemical CO reductions over copper-based catalysts. However, precisely controlling the favorable nanograin boundaries with surface structures (e.g., Cu(100) facets and Cu[ (100)×(110)] step sites) and simultaneously stabilizing Cu /Cu interfaces is challenging, since Cu species are highly susceptible to be reduced into bulk metallic Cu at high current densities. Thus, an in-depth understanding of the structure evolution of the Cu-based catalysts under realistic CO RR conditions is imperative, including the formation and stabilization of nanograin boundaries and Cu /Cu interfaces. Herein we demonstrate that the well-controlled thermal reduction of Cu O nanocubes under a CO atmosphere yields a remarkably stable Cu O-Cu nanocube hybrid catalyst (Cu O(CO)) possessing a high density of Cu /Cu interfaces, abundant nanograin boundaries with Cu(100) facets, and Cu[ (100)×(110)] step sites. The Cu O(CO) electrocatalyst delivered a high C Faradaic efficiency of 77.4% (56.6% for ethylene) during the CO RR under an industrial current density of 500 mA/cm . Spectroscopic characterizations and morphological evolution studies, together with time-resolved attenuated total reflection-surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) studies, established that the morphology and Cu /Cu interfacial sites in the as-prepared Cu O(CO) catalyst were preserved under high polarization and high current densities due to the nanograin-boundary-abundant structure. Furthermore, the abundant Cu /Cu interfacial sites on the Cu O(CO) catalyst acted to increase the *CO adsorption density, thereby increasing the opportunity for C-C coupling reactions, leading to a high C selectivity.