Gas diffusion electrode can enhance mass transfer of CO2 for CO2 electrochemical reduction. A carbon felt loaded Sn-graphene gas diffusion electrode for electrochemical reduction of CO2 to formic acid. Effects of CO2 reaction condition

electrode thickness

Sn loading and electrolytic potential were studied. The results showed that the performance of CO2 electrochemical reduction was better under the gas phase CO2 reaction condition than that under dissolved CO2 condition. Increasing the electrode thickness or Sn loading within an appropriate range led to an improvement in electrochemical reduction of carbon dioxide to formic acid due to the increase in the gas-liquid-solid three-phase interface. The production of formic acid was raised with the negative shift of the electrolytic potential

while the Faraday efficiency increased at first and then decreased. The average current density of (12.79±1.27)mA·cm-2 and highest Faraday efficiency of 41.55%±2.50% for electrochemical reduction of carbon dioxide to formic acid were obtained at -1.8 V (vs Ag/AgCl) using the carbon felt electrode with the electrode thickness of 5 mm and Sn loading of 5 mg·cm-2.