ZnIn2S4/g-C3N4 binary heterojunction nanostructure for enhancing visible light CO2 reduction at the reaction interface

ZnIn2S4 demonstrated excellent compatibilities with the band gap of g-C3N4, which enhanced both light absorption and charge transfer abilities. In this work, ZnIn2S4/g-C3N4 (ZIS/CN) binary heterojunction materials were synthesized using a hydrothermal approach and evaluated based on mass ratios, hydrothermal temperatures and stability. The optimized catalyst, ZIS40/CN60-165 degrees C (mass fraction of ZIS was 40 %, hydrothermal temperature was 165 degrees C) demonstrated CH4 and CO production rate of 3.66 and 4.7 mu mol g- 1 h- 1, respectively. Furthermore, ZIS40/CN60-165 degrees C exhibited almost no change in CH4 and CO yields during a continuous operation test lasting up to 105 h. The outstanding catalytic performance of ZIS40/CN60-165 degrees C could be attributed to several factors: (1) Sulfur vacancies acted as electron capture centers, facilitating electron transfer. (2) The formation of heterojunction compared to CN led to a reduced band gap, enhancing photo-responsiveness of the material. (3) The intrinsic electric field effect within catalyst served as driving forces for CO2 reduction, efficiently directing photogenerated carriers between ZIS and CN. (4) The integration of two semiconductors offered more adsorption sites, leading to higher CO2 adsorption capacity of 1.7 mmol/g. The results offer critical understanding for advancing developments of selective photocatalysts aimed at sustainable CO2 utilization.