Dimensionally Intact Construction of Ultrathin S-Scheme CuFeO/ZnInS Heterojunctional Photocatalysts for CO Photoreduction.

The conversion of CO into carbon-neutral fuels such as methane (CH) through selective photoreduction is highly sought after yet remains challenging due to the slow multistep proton-electron transfer processes and the formation of various C intermediates. This research highlights the cooperative interaction between Fe and Cu ions transitioning to Fe and Cu ions, enhancing the photocatalytic conversion of CO to methane. We introduce an S-scheme heterojunction photocatalyst, CuFeO/ZnInS, which demonstrates significant efficiency in CO methanation under light irradiation. The CuFeO/ZnInS heterojunction forms an internal electric field that aids in the mobility and separation of exciton carriers under a wide solar spectrum for exceptional photocatalytic performance. Remarkably, the optimal CuFeO/ZnInS heterojunction system achieved an approximately 68-time increase in CO conversion compared with ZnInS and CuFeO nanoparticles using only pure water, with nearly complete CO selectivity and yields of CH and CO reaching 172.5 and 202.4 μmol g h, respectively, via a 2-electron oxygen reduction reaction (ORR) process. The optimally designed CuFeO/ZnInS heterojunctional system achieved approximately 96% conversion of BA and 98.5% selectivity toward benzaldehyde (BAD). Additionally, this photocatalytic system demonstrated excellent cyclic stability and practical applicability. The photogenerated electrons in the CuFeO conduction band enhance the reduction of Fe/Cu to Fe/Cu, creating a microenvironment conducive to CO reduction to CO and CH. Simultaneously, the appearance of holes in the ZnInS valence band facilitates water oxidation to O. The synergistic function within the CuFeO/ZnInS heterojunction plays a pivotal role in facilitating charge transfer, accelerating water oxidation, and thereby enhancing CO reduction kinetics. This study offers valuable insights and a strategic framework for designing efficient S-scheme heterojunctions aimed at achieving carbon neutrality through solar fuel production.