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The electroreduction of carbon dioxide (CO2 RR) to CH4 stands as one of the promising paths for resourceful CO2 utilization in meeting the imminent "carbon-neutral" goal of the near future. Yet, limited success has been witnessed in the development of high-efficiency catalysts imparting satisfactory methane selectivity at a commercially viable current density. Herein, a unique category of CO2 RR catalysts is fabricated with the yolk-shell nanocell structure, comprising an Ag core and a Cu2 O shell that resembles the tandem nanoreactor. By fixing the Ag core and tuning the Cu2 O envelope size, the CO flux arriving at the oxide-derived Cu shell can be regulated, which further modulates the *CO coverage and *H adsorption at the Cu surface, consequently steering the CO2 RR pathway. Density functional theory simulations show that lower CO coverage favors methane formation via stabilizing the intermediate *CHO. As a result, the best catalyst in the flow cell shows a high CH4 Faraday efficiency of 74 ± 2% and partial current density of 178 ± 5 mA cm- 2 at -1.2 VRHE , ranking above the state-of-the-art catalysts reported today for methane production. These findings mark the significance of precision synthesis in tailoring the catalyst geometry for achieving desired CO2 RR performance.
Xiong et al. (Mon,) studied this question.