Highly Selective and Efficient Electroreduction of Carbon Dioxide to Carbon Monoxide with Phosphate Silver-Derived Coral-like Silver

Electrochemical reduction of carbon dioxide (CO2RR) to useful chemicals and fuels is one of the promising methods to reduce the accumulated greenhouse gas in the atmosphere and simultaneously satisfy sustainable energy demands. Metallic Ag has been reported in numerous studies for its excellent properties in CO2 reduction. However, most Ag catalysts require a large overpotential to realize high selectivity and the Faradaic efficiency (FE) is relatively low. Moreover, the synthetic methods of efficient Ag catalysts are usually complicated and time-consuming. In this work, a phosphate silver-derived silver (PD-Ag) electrocatalyst was fabricated by a quick facile electroreduction method, showing superior performance for the selective reduction of CO2 to CO. The maximum FE of PD-Ag could reach 97.3% with a potential of −0.7 V vs RHE, and a current density of 2.93 mA cm–2. It is demonstrated that a 19-fold increase of the electrochemically active surface area (ECSA) is obtained for PD-Ag compared to polycrystalline Ag (Ag foil). Furthermore, PD-Ag shows an excellent stability during a 10 h electrolysis with only 4% loss of the current. The enhancement of the electroactivity results from its coral-like surface, not only serving plenty of active sites, but also producing CO2– intermediate at a lower overpotential.