Electrohydrogenation of Carbon Dioxide using a Ternary Pd/Cu₂ O-Cu Catalyst

A simple one-pot method has been developed to synthesize a palladium/cuprous oxide-copper (Pd/Cu₂ O-Cu) material with a well-defined structure, by modification of Cu₂ O-Cu with Pd through a galvanic replacement reaction. Compared with the well-known copper/cuprous oxide (Cu/Cu₂ O) catalysts, the Pd/Cu₂ O-Cu material can catalyze the electroreduction of CO₂ into C₁ products with much higher faradaic efficiencies at lower overpotentials in a CO₂ -saturated 0.5 m NaHCO₃ solution. In particular, the highest faradaic efficiencies of 92 % for formate and 30 % for methane were achieved at -0.25 and -0.65 V (vs. the reversible hydrogen electrode), respectively. The improvement is suggested to be the result of a synergistic effect between PdH and the catalytically active copper sites during electrochemical CO₂ reduction.