Constructing nano-Au/reduced-CeO2 interface through high cathodic voltage in solid oxide electrolysis cells at high temperature

CeO2 is often used as the buffer layer for CO2 electroreduction in solid oxide electrolysis cells (SOECs) because of their limited electrocatalytic activity and low reactivity with electrolytes and electrodes. In this work, we propose a novel cathodic electrochemically activation method to construct a nano-Au/reduced-CeO2 interface, and achieve significantly improved CO2 electroreduction performance. The Gd-doped CeO2 (GDC) cathode activated at 2.9 V exhibits the highest current density of 0.241 A cm−2 at 1.2 V, which is 3.65 times that of the GDC cathode activated at 2.0 V. After being activated at 2.9 V, lots of oxygen vacancies are generated on the surface of ceria-based-cathodes, which facilitate the Au nanoparticles dispersion and enhance CO2 adsorption. Au nanoparticles, reduced-ceria particles and CO2 gas together form lots of three-phase boundaries (TPBs), which are beneficial for CO2 electroreduction. Our work explores a novel cathodic electrochemically activation method to restructure the metal-oxides interface.