Artificial photosynthesis of ethanol using type-II g-C3N4/ZnTe heterojunction in photoelectrochemical CO2 reduction system

Constructing heterojunctions and designing advanced structures to mimic natural photosynthesis is an effective route to convert CO2 into high-energy chemicals with high efficiency and selectivity. Compared to a single-component catalyst, those of two components with different function can corporately facilitate the formation of C-2 products. Herein, a type-II heterojunction based on graphitic carbon nitride (g-C3N4)/ZnTe was constructed for the first time for photoelectrochemical CO2 reduction, yielding an impressive ethanol generation rate of 17.1 mu mol cm(-2)h(-1) at -1.1 V (vs. Ag/AgCl). The heterojunction accelerates separation of photo-generated electron-hole pairs and transfer of electrons from ZnTe to g-C3N4 driving by an interfacial internal electric field (IEF) formed between the two semiconductors. Moreover, the combination of ZnTe of high CO2 adsorption capacity serves as CO-producing site with g-C3N4 featuring of abundant pyridinic N subsequently accomplishes the C-C coupling process via adsorbing CO and proton-coupled electron transfer. A pipelined mechanism to rationalize the selective reduction of CO(2 )to ethanol is proposed and discussed.