Investigating the Effect of the Initial Valence States of Copper on CO2 Electroreduction

Abstract

AbstractAbstract: The valence states of copper always play an important role for the most studied copper‐based catalysts in CO2 electroreduction (CO2ERR). In this work, distinct Cu, Cu2O, and CuO nanoparticles with similar particle size on active carbon are synthesized via carbonthermal reduction. Although all CuOx nanoparticles are reduced to metallic Cu during CO2ERR, their different initial valence states result in particle‐size variations and different CO2ERR performances. Cu nanoparticles in Cu/C evolve into smaller particles, while those derived from Cu2O/C and CuO/C agglomerate into larger ones. The optimal CO production potential of CO drops with decreasing particle size and is as low as −0.7 V (vs. the eversible hydrogen electrode) on Cu/C. Furthermore, Cu nanoparticles in Cu/C expose much more active sites with higher electrochemical active area and stronger CO adsorption, which further promote C−C coupling to produce C2+ products while inhibiting competitive hydrogen evolution.