Electrochemical Reduction of High Pressure  CO 2 on Ni Electrodes

The electrochemical reduction of under high pressures of was investigated on Ni electrodes. With an increase in pressure, the Faradaic efficiency for reduction was increased while that of evolution by water reduction was decreased. Current density at −1.8 V vs. did not depend greatly on pressure at 30°C. By increasing temperature, the Faradaic efficiency for hydrocarbon formation was increased, suggesting that thermal activation was needed, although the total reduction efficiency for reduction was decreased. The Faradaic efficiency for the hydrocarbon formation showed a maximum at −1.6 V , while those for and were increased with increasing cathodic polarization. The weight distribution of hydrocarbons formed on Fe, Co, and Ni electrodes agreed well with the Schultz‐Flory distribution, indicating that hydrocarbons were formed via a mechanism similar to a Fischer‐Tropsch reaction for thermal catalysis, i.e., polymerization of surface carbene groups produced by the reduction of which was formed by reduction.