Abundant Ce3+ Ions in Au‐CeOx Nanosheets to Enhance CO2 Electroreduction Performance

Abstract The electroreduction of CO 2 to CO provides a potential way to solve the environmental problems caused by excess fossil fuel utilization. Loading transition metals on metal oxides is an efficient strategy for CO 2 electroreduction as well as for reducing metal usage. However, it needs a great potential to overcome the energy barrier to increase CO selectivity. This paper describes how 8.7 wt% gold nanoparticles (NPs) loaded on CeO x nanosheets (NSs) with high Ce 3+ concentration effectively decrease the overpotential for CO 2 electroreduction. The 3.6 nm gold NPs on CeO x NSs containing 47.3% Ce 3+ achieve CO faradaic efficiency of 90.1% at −0.5 V in 0.1 m KHCO 3 solution. Furthermore, the CO 2 electroreduction activity shows a strong relationship with the fractions of Ce 3+ on Au‐CeO x NSs, which has never been reported. In situ surface‐enhanced infrared absorption spectroscopy shows that Au‐CeO x NSs with high Ce 3+ concentration promote CO 2 activation and *COOH formation. Theoretical calculations also indicate that the improved performance is attributed to the enhanced *COOH formation on Au‐CeO x NSs with high Ce 3+ fraction.