Excellent performance of the photoelectrocatalytic CO2 reduction to formate by Bi2S3/ZIF-8 composite

Photoelectrocatalytic reduction of CO2 to formate is anticipated to be an effective method to reduce the atmospheric CO2 content and alleviate the fossil energy crisis. However, the inherent chemical inertness and low solubility in the electrolyte of CO2 restricts the further development of photoelectrocatalytic reduction technology. In this work, ZIF-8, a new porous crystal material, was used as the host material to capture and activate CO2 molecules and was composited with Bi2S3 semiconductor material for the photoelectrocatalytic reduction of CO2 to formate. A high activity was observed for the photoelectrocatalytic CO2 reduction synthesis of formate at the potential of −0.7 V (relative to RHE). The total current density at this potential was 16.1 mA·cm−2, in which the Faraday efficiency of formate was 74.2%. 10-Bi2S3/ZIF-8 catalyst showed no performance attenuation in the stability test up to 12 h. The energy band structures of Bi2S3 and ZIF-8 were studied by UV diffuse reflection absorption spectroscopy and revealed the reason for the high activity and high selectivity of the photoelectrocatalytic CO2 reduction synthesis of formate.