Operando Reconstruction of CuO/SnO 2 Nanosheets Promotes the Syngas Production from the Electrochemical CO 2 Reduction Reaction

Electrochemically reducing CO (CO RR) to high-value chemical products is recognized as a promising route to simultaneously reduce the consumption of fossil fuels and carbon emission. The fabrication of syngas with an appropriate H /CO ratio by CO RR has been widely studied, but the dynamic evolution of the catalyst is still ambiguous. Herein, the reconstruction of CuO/SnO nanosheets (NSs) with a heterojunction structure in the CO RR process was reported by an in situ X-ray diffractometer technique. The products of the CO RR on the optimized CuO/SnO NSs are CO and H , achieving a nearly 100% total Faraday efficiency. Moreover, the resulting syngas is maintained at a constant 2:1 ratio of H /CO over a wide potential of -0.8 to -1.2 V versus the reversible hydrogen electrode. Importantly, the detailed characterizations show that Cu is reduced to Cu during the CO RR process, while the valence state of Sn remains stable. This study presents strong experimental support for the dynamic evolution process of electrocatalysts in other energy conversion fields.