Preparation of oxygen vacancy-rich 3D-Ag nanosheet arrays electrodes for efficient CO2 reduction into CO through in situ oxidation-reduction

Enhancing the working current density is a great challenge that limits the practical applications of the CO 2 electrochemical reduction. In this study, a facile method was developed to prepare 3D-Ag nanosheet arrays (3DAg NA) electrodes for efficient CO 2 reduction into CO through in situ oxidation-reduction. The resulting electrodes exhibited high specific surface area and abundant oxygen vacancies. 3D-Ag NA on Ag foil electrode (3DAg NA/Ag) demonstrated a significantly enhanced current density of 25.9 mA/cm 2 at -1.06 V vs. RHE in an Hcell, surpassing the performance of Ag foil, Ag nanoparticles and Ag 2 O nanoparticles electrodes. Moreover, 3DAg NA on low cost graphite (3D-Ag NA/C) showed a current density of 24.3 mA/cm 2 at a remarkble low potential of -0.96 V vs. RHE. It was found that the formation of a dense Ag 2 O layer play a critical role in the establishing the 3D-Ag NA. Furthermore, CO 2 -TPD and DFT studies revealed that the 3D-Ag NA exhibited high CO 2 adsorption capacity and low CO 2 activation energy. This study presents a promising approach for scalable electrode preparation in the electrochemical reduction of CO 2 to CO, enabling high current density and selectivity.