Artificial Photosynthesis for Formaldehyde Production with 85% of Faradaic Efficiency by Tuning the Reduction Potential

作者：Kim Chang Woo; Kang Myung Jong; Ji Sohyun; Kang Young Soo

来源：ACS Catalysis, 2018, 8(2): 968-974.

DOI：10.1021/acscatal.7b02953

• solar energy
• solar fuel
• water splitting
• CO2 reduction
• reduction potential

In the present study, artificial photosynthesis by CO2 reduction in NaCl is studied for solar fuel production. C1 fuels are evolved from various photoelectrochemical reactions at different reduction potentials depending on the multistep electron-transfer processes to CO2. The (040) facet engineered BiVO4 (040-BVO)vertical bar NaCl vertical bar Cu system is illuminated with solar light, and the external bias potential is tuned from 0.7 V to 1.5 (vs RHE) for the CO2 reduction reaction. Integrating the applied external bias potential into the conduction band minimum of 040-BVO enables the CO2 molecules to be converted into valuable chemical fuels. This thermodynamic control leads to product selectivity and increased faradaic efficiency. We observed that the selectivity and yield of the products depend on the magnitude of the CO2 reduction potential. Its products were obtained by tuning the appropriate reduction potential, leading to faradaic efficiencies of 62% for formic acid, 85% for formaldehyde, 8% for MeOH, and 6% for EtOH at different bias in NaCl electrolyte. The correlation between the production of solar chemical fuels and CO2 reduction potential tuning was studied by applying an external bias potential on 040-BVO vertical bar NaCl vertical bar Cu. The Cu-C bond distance change during photoelectrochemical CO2 reduction reaction was investigated with in situ synchrotron X-ray. We suggest that the present results represent the most viable strategy to selectively and efficiently produce solar fuels via artificial photosynthesis.

• 出版日期2018-2