Reduction of carbon dioxide in 3-dimensional gas diffusion electrodes

Experiments on the electrochemical reduction of CO2 were carried out by usi ng a Cu/PTFE-bonded gas diffusion electrode (GDE) to investigate the effect of solvents, Cu/C ratio and electrolyte concentration on the characteristi cs of reduction products. The experimental conditions were a voltage range from -2.0 to -3.5 V vs. saturated calomel electrode (SCE) and electrolyte c oncentration from 0.1 M to 0.5 M. Significant performance differences were found between water and organic solvent (isobutanol+EtOH). The GDE was more active with water than that with organic solvent. And then, in the case of the Cu/PTFE-bonded gas diffusion electrode using organic solvent, the maxi mum faradaic efficiencies of reduction products were achieved in a Cu/C rat io of 0.5. The faradaic efficiency of C2H4 among the reduction products dec reased as the Cu/C ratio increased; whereas, those of CO and alcohol increa sed. Since the difference in pH at the electrode influences the variation o f product selectivity, the faradaic efficiency of C2H4 might increase due t o the pH increase caused by electrolyte concentration difference.