Dendritic Ag Electrocatalyst with High Mass-Specific Activity for Zero-Gap Gas-Fed CO2 Electroreduction

Electrodeposited silver catalyst is attractive compared to commercially available silver nanoparticles because it allows for the investigation of catalyst morphology and crystallography on the performance of CO2 electrolyzer for the conversion of CO2 to CO. In this work, Ag electrodes with different Ag structures varying from polycrystalline to dendrite were fabricated by controlling different electrodeposition parameters: deposition voltage, ethylenediamine additive and ammonium sulfate concentration, and time of deposition. The electrode performance was evaluated in a zero-gap, gas-fed, polymer electrolyte membrane-based cell. The highest mass-specific activity of 362 mA·mgAg–1 and a CO selectivity of 94% at a cell potential of 3 V were achieved for dendritic Ag catalyst (0.29 mg·cm–2) that possessed the maximum (220)/(111) facet ratio, as determined by X-ray diffraction. The long-term durability test on the electrode demonstrated a robust performance after 100 h of CO2 reduction at a 3 V cell voltage.