Silver Supported on Titania as an Active Catalyst for Electrochemical Carbon Dioxide Reduction

Abstract Although significant research efforts have focused on the exploration of catalysts for the electrochemical reduction of CO 2 , considerably fewer reports have described how support materials for these catalysts affect their performance, which includes their ability to reduce the overpotential, and/or to increase the catalyst utilization and selectivity. Here Ag nanoparticles supported on carbon black (Ag/C) and on titanium dioxide (Ag/TiO 2 ) were synthesized. In a flow reactor, 40 wt % Ag/TiO 2 exhibited a twofold higher current density for CO production than 40 wt % Ag/C. Faradaic efficiencies of the 40 wt % Ag/TiO 2 catalyst exceeded 90 % with a partial current density for CO of 101 mA cm −2 ; similar to the performance of unsupported Ag nanoparticle catalysts (AgNP) but at a 2.5 times lower Ag loading. A mass activity as high as 2700 mA mg Ag −1 cm −2 was achieved. In cyclic voltammetry tests in a three‐electrode cell, Ag/TiO 2 exhibited a lower overpotential for CO 2 reduction than AgNP, which, together with other data, suggests that TiO 2 stabilizes the intermediate and serves as redox electron carrier to assist CO 2 reduction while Ag assists in the formation of the final product, CO.