Highly Selective Conversion of CO₂ to CO Achieved by a Three-Dimensional Porous Silver Electrocatalyst

A three-dimensional, porous silver foam catalyst was fabricated by a simple electrodeposition approach under high applied currents and vigorous hydrogen evolution conditions. The as-prepared catalyst can be used directly as the working electrode for electrochemical reduction of CO₂ without further treatments, which can reduce CO₂ selectively to CO with a high Faradaic Efficiency of 94.7 % and a large current density of 10.80 mA cm⁻² at an applied potential of −0.99 V. The performance tradeoff between CO Faradaic Efficiency (FE_CO) and current density is successfully circumvented with the novel foam structured catalyst, which is capable of delivering high value of FE_CO as well as large current densities (>10 mA cm⁻²). The enhanced catalytic performances can be attributed to the unique configuration of the three dimensional, highly porous Ag foam electrode, which not only offers high electrode integrity, conductivity and stability, but also possess large surface area with active sites and easily accessible pores that allow facile transportation of reactants (CO₂ and H₂O) and products (CO and H₂).