RETRACTED: Dimensionally Intact Construction of Ultrathin S-Scheme CuFe₂O₄/ZnIn₂S₄ Heterojunctional Photocatalysts for CO₂ Photoreduction

Abstract

The conversion of CO 2 into carbon-neutral fuels such as methane (CH 4 ) 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 1 intermediates. This research highlights the cooperative interaction between Fe 3+ and Cu 2+ ions transitioning to Fe 2+ and Cu + ions, enhancing the photocatalytic conversion of CO 2 to methane. We introduce an S-scheme heterojunction photocatalyst, CuFe 2 O 4 /ZnIn 2 S 4 , which demonstrates significant efficiency in CO 2 methanation under light irradiation. The CuFe 2 O 4 /ZnIn 2 S 4 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 CuFe 2 O 4 /ZnIn 2 S 4 heterojunction system achieved an approximately 68-time increase in CO 2 conversion compared with ZnIn 2 S 4 and CuFe 2 O 4 nanoparticles using only pure water, with nearly complete CO selectivity and yields of CH 4 and CO reaching 172.5 and 202.4 μmol g −1 h −1 , respectively, via a 2-electron oxygen reduction reaction (ORR) process. The optimally designed CuFe 2 O 4 /ZnIn 2 S 4 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 CuFe 2 O 4 conduction band enhance the reduction of Fe 3+ /Cu 2+ to Fe 2+ /Cu + , creating a microenvironment conducive to CO 2 reduction to CO and CH 4 . Simultaneously, the appearance of holes in the ZnIn 2 S 4 valence band facilitates water oxidation to O 2 . The synergistic function within the CuFe 2 O 4 /ZnIn 2 S 4 heterojunction plays a pivotal role in facilitating charge transfer, accelerating water oxidation, and thereby enhancing CO 2 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.