An electrochemical reduction of CO2 to CO has become a challenging issue in CO2 utilization in order to mitigate the climate change. In this study, we report a promising approach to prepare Au-based electrocatalysts for the electrochemical reduction of CO2 to CO having the maximized activity/selectivity and the minimized Au usage. It was clearly confirmed that the Au thin layer formed by the electrochemical galvanic displacement on polycrystalline Cu surface resulted in a markedly enhanced performance for the electrochemical reduction of CO2 to CO. The CO Faradaic efficiency for the Au thin layer on Cu was 10.6 and 3.4 times higher than that for the polycrystalline Cu and Au, respectively. It was revealed from the photoemission spectroscopy (PES) studies that the increase of electron population in s-band and the upshift of d-band center position of Au in Au/Cu increased the bond strength with reaction intermediates leading to the enhancement of activity and the selectivity. Along with the electronic effect, the geometric effect like the increased the electrochemical surface area (ECSA) and proportion of low coordinated sites also played a substantial role in the performance enhancement. (C) 2017 Elsevier B.V. All rights reserved.