CO 2 ‐to‐HCOOH Electrochemical Conversion on Nanostructured Cu x Pd 100−x /Carbon Catalysts

Selective electrochemical conversion of CO 2 to HCOOH is obtained at the surface of a carbon‐supported bimetallic cathode material composed of copper and palladium nanoparticles. Polycrystalline copper or large copper particles are well‐known to catalyze CO 2 reduction to hydrocarbons at relatively negative potentials, or when their surface is covered by copper oxides (Cu 2 O and CuO). Cu‐based materials modified by various palladium contents (0<×<100), were synthesized by using the microwave‐assisted polyol method to serve as a cathode in the selective CO 2 ‐into‐HCOOH transformation. Herein, we developed a targeted preparation route toward the metal content/catalytic activity relationship correlating atomic ratio with faradaic efficiency (FE) to formate formation (ca. 60 % FE) at −0.72 V vs. RHE, which represents a 703 mV overpotential at pH=7. Consequently, the occurrence of this reduction reaction slows down the parallel H 2 production from the solvent consumption, while the neighboring Cu−Pd provides excellent activity and a good efficiency toward CO 2 reduction via the hydridation of the CO 2 molecule to orientate the reaction to formate rather than carbon monoxide or H 2 evolution.