Design and Preparation of ZnIn2S4/g-C3N4 Z-Scheme Heterojunction for Enhanced Photocatalytic CO2 Reduction

In this study, a novel Z-scheme heterojunction photocatalyst was developed by integrating g-C3N4nanoplates into ZnIn2S4microspheres. X-ray photoelectron spectroscopy analysis revealed a directional electron transfer from g-C3N4to ZnIn2S4upon heterojunction formation. Under irradiation, electrochemical tests and electron paramagnetic resonance spectroscopy demonstrated significantly enhanced charge generation and separation efficiencies in the ZnIn2S4/g-C3N4composite, accompanied by reduced charge transfer resistance. In photocatalytic CO2reduction, the ZnIn2S4/g-C3N4composite achieved the highest CO yield, 1.92 and 5.83 times higher than those of pristine g-C3N4and ZnIn2S4, respectively, with a notable CO selectivity of 91.3% compared to H2(8.7%). The Z-scheme heterojunction mechanism, confirmed in this work, effectively preserved the strong redox capabilities of the photoinduced charge carriers, leading to superior photocatalytic performance and excellent long-term stability. This study offers valuable insights into the design and development of g-C3N4-based heterojunctions for efficient solar-driven CO2reduction.