In the photoelectrochemical CO₂ reduction reaction, water oxidation reaction is performed on 040-BVO and chemical fuels is obtained on Cu cathode in the CO₂-saturated NaCl electrolyte under AM 1.5 G. C1 chemical fuel is evolved through reduction potential depending multistep process from CO₂ molecule. 040-BVO(photoanode)/NaCl(electrolyte)/Cu(cathode) system is illuminated with solar light under the external bias that is tailored to reduce CO₂ via reduction potential tuning. Integrating applied bias potential into conduction band minimum of 040-BVO enables CO₂ molecules to be converted into valuable chemical fuels. We observe that the selectivity and yield of the products depend on CO₂ reduction potential tuning. With water oxidation reaction of 040-BVO photoanode which has 42.1% of the absorbed photon-to-current conversion efficiency at 1.23 V (vs RHE), chemical products were observed as faradaic efficiency of 30% formic acid, 60% formaldehyde, 12% MeOH and 3% EtOH by reduction potential tuning. For this study, the correlation between the production of solar chemical fuels and CO₂ reduction potential tuning via external bias potential on 040-BVO photoanode/Cu photocathode is systematically investigated.

Keywords: Artificial photosynthesis; Multi-electron shuttling; CO₂ reduction potential tuning