Photoelectrochemical Reduction of Highly Concentrated CO2 Using a p-InP Electrode

Carbon dioxide was photoelectrochemically reduced at a p-type InP photocathode in highly concentrated CO₂ solution in methanol at elevated pressure (40 atm). Relatively high current densities were achieved (200 mA/cm²) with high current efficiencies for CO production (~90%). These current densities are approximately an order of magnitude higher than those reported previously in the literature for photoelectrochemical reduction due to the very high CO₂ concentration (~8 mol/L). Other products were hydrogen and methyl formate (produced via reaction between formic acid and the methanol solvent), Hydrocarbons were produced in only trace amounts.