Photoelectrocatalytic CO2 Reduction to Formate Using a BiVO4/ZIF‐8 Heterojunction

Converting CO2 into high-value chemical fuels through green photoelectrocatalytic reaction path is considered as a potential strategy to solve energy and environmental problems. In this work, BiVO4/ZIF-8 heterojunctions are prepared by in-situ synthesis of ZIF-8 nanocrystals with unique pore structure on the surface of BiVO4. The experimental results show that the silkworm pupa-like BiVO4 is successfully combined with porous ZIF-8, and the introduction of ZIF-8 can provide more sites for CO2 capture. The optimal composite ratio of 4:1-BiVO4/ZIF-8 showed excellent CO2 reduction activity and the lowest electrochemical transport resistance. In the electrocatalytic system, 4:1-BiVO4/ZIF-8 exhibits formate Faraday efficiency of 82.60% at -1.0 V vs. RHE. Furthermore, the Faraday efficiency increases to 91.24% at - 0.9 V vs. RHE in the photoelectrocatalytic system, which is 10.8 times that of pristine BiVO4. The results show that photoelectric synergism can not only reduce energy consumption, but also improve the Faraday efficiency of formate. In addition, the current density did not decrease during 34 h electrolysis, showing long-term stability. This work highlights the importance of the construction of heterojunction to improve the performance of photoelectrocatalytic CO2 reduction.