MOF-derived g-C3N4/ZnIn2S4 S-scheme heterojunction: Interface-engineering enhanced photocatalytic NO conversion

Addressing the growing challenge of nitrogen oxides (NO_x) pollution in the atmosphere requires the development of photocatalysts with both high efficiency and strong selectivity. In this study, a g-C₃N₄/ZnIn₂S₄ (CN/ZIS) S-scheme heterojunction photocatalyst was constructed, in which ZnIn₂S₄ with a hollow tubular morphology was synthesized via a MOF-derived strategy, and g-C₃N₄ served as an efficient electron transfer platform. The optimized CN/ZIS-0.1 exhibited remarkable photocatalytic efficacy under visible-light radiation, attaining a NO removal efficiency of 67.29 %, markedly surpassing that of pristine g-C₃N₄ (41.41 %) and ZIS (27.8 %). Additionally, a high NO-to-nitrate selectivity of 77.47 % was attained, exceeding that of pristine g-C₃N₄ (49.01 %). The material characterization results revealed that CN/ZIS-0.1 not only has a wider light absorption range but also its unique structure provides more reaction sites. Further photoelectrochemical measurements and DFT simulations confirm that the built-in electric field (BIEF) formed at the CN/ZIS interface facilitates the directional migration of photogenerated electrons towards the g-C₃N₄ surface, and photogenerated holes migrate towards the surface of ZIS, thereby promoting the generation of key reactive species and enhancing NO adsorption. This work not only demonstrates the potential of constructing S-scheme heterojunctions by coupling MOF-derived hollow structures with two-dimensional semiconductors for NO oxidation, but also offers an effective strategy for developing highly selective NO photocatalysts.