<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.

Zhang, Lixiao; Li, Xiaobao; Lu, Jianmin; Zhang, Liming; Hu, Shiqing; Gong, Huimin; Liu, Xuan; Mao, Baohua et al. · Nano Lett · 2021

basic_science · Level V

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Abstract

CO<sub>2</sub> electrochemical reduction in solid oxide electrolysis cells is an effective way to combine CO<sub>2</sub> 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, <i>in situ</i> 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.