<i>In situ</i> Dispersed Nano-Au on Zr-Suboxides as Active Cathode for Direct CO<sub>2</sub> Electroreduction in Solid Oxide Electrolysis Cells
Lixiao Zhang, Xiaobao Li, Jianmin Lü, Liming Zhang, Shiqing Hu, Huimin Gong, Xuan Liu, Baohua Mao, Xuefeng Zhu, Zhi Liu, Weishen Yang
Abstract
CO2 electrochemical reduction in solid oxide electrolysis cells is an effective way to combine CO2 conversion and renewable electricity storage. A Au layer is often used as a current collector, whereas Au nanoparticles are rarely used as a cathode because it is difficult to keep nanosized Au at high temperatures. Here we dispersed a Au layer into Au nanoparticles (down to 2 nm) at 800 °C by applying high voltages. A 75-fold decrease in the polarization resistance was observed, accompanied by a 38-fold improvement in the cell current density. Combining electronic microscopy, in situ near-ambient pressure X-ray photoelectron spectroscopy, and theoretical calculations, we found that the interface between the Au layer and the electrolyte (yttria-stabilized zirconia (YSZ)) was reconstructed into nano-Au/Zr-suboxide interfaces, which are active sites that show a much lower reaction activation energy than that of the Au/YSZ interface. The formation of Zr-suboxides promotes Au dispersion and Au nanoparticle stabilization due to the strong interaction between Au and Zr-suboxides.