Regulating the photoelectrocatalytic reduction efficiency of CO2 to syngas via SnO enhanced g-C3N4 based p-n heterojunction

Abstract

Photoelectrochemical reduction of CO2 with H2O into syngas (H2/CO) is considered as an important platform to organic chemicals, which can effectively alleviate the greenhouse effect and energy dependence. We synthesized SnO/g-C3N4 p-n junction catalyst with matched energy band, which shows enhanced light absorption performance and photogenerated charge separation efficiency. The M − S plots verified the successful construction of p-n type heterojunctions, and the investigations of LSV, EIS, PL and transient photocurrents test indicate that the recombination rate of charge is well inhibited by the design of p-n heterojunction. In this work, the syngas derived from PEC reduction of CO2 and H2O is achieved by the SnO/g-C3N4 photocathode with a total FE of 70% at an external bias of −1.5 V. In addition, the H2/CO molar ratio can be tuned from 1.5 to 10 by controlling the applied voltage. The study may inspire a new thought for the design of high-performance photoelectric catalyst and a promising strategy for PEC CO2 reduction to valuable carbon-based compounds.