In Situ Electrochemical Route to Bromide Anion-Adsorbed Coral-like Porous Silver Microspheres Achieving Highly Selective Electroreduction of CO2 to CO over a Wide Potential Range

Silver catalysts play an irreplaceable role in the electroreduction of CO2 to CO. Here, we report the structure of bromide anion-adsorbed coral-like porous microspheres of silver (Ag BACPSs). They are formed by in situ electrolysis of AgBr microparticles (AgBr MPs) at a very low potential of −0.8 V (vs reversible hydrogen electrode (RHE)). Each AgBr MP is completely transformed into a porous coral-like microsphere, and the mass activity is greatly improved. Simultaneously, every microsphere has an interconnected open-pore structure, and all surfaces of the material adsorb bromide anions. The increased active electron density on the surface of the material helps the CO2 to obtain electrons on the surface of the electrocatalyst to form active species, which improves the selectivity of the catalytic material. Over a wide range of −0.4 to −0.9 V (vs RHE), the faradic efficiency for CO can be maintained above 91%, and the highest point can reach 98.7% at −0.6 V (vs RHE) in 0.5 M KHCO3 solution. In addition, it has excellent stability. The obtained catalyst material has good large-scale application prospects.