Selective liquid chemicals on CO2 reduction by energy level tuned rGO/TiO2 dark cathode with BiVO4 photoanode

Photoelectrochemical (PEC) CO2 reduction reaction (CO2RR) has challenged a selectivity and conversion efficiency of chemical fuels resulting by the interfacial reaction on cathode itself. Herein, a reduced graphene oxide (rGO) layered TiO2 was firstly studied as dark cathode for selective production of liquid fuels, with BiVO4 photoanode. (040) crystal facet engineered BiVO4│KHCO3│rGO/TiO2 combination is introduced in this study. A different free energy level of electrons involves in CO2RR, which is controlled by band energy adjustment via varying reduction degrees of rGO layer on TiO2 electrode. The relative number and lifetimes of the excited state electrons on GO/rGO functional layer on TiO2 investigated by time-resolved photoluminescence spectroscopy. The mechanism and pathway of liquid product selectivity has been suggested based on 13C isotope labelling technique and in-situ electron paramagnetic resonance spectroscopy. Above results represent the viable strategy to get high product selectivity during artificial photosynthesis reaction.