Interfacial Ce‐S bonds enhanced Mo‐doped ZnIn₂S₄/oxygen‐deficient CeO₂ S‐scheme heterojunction for efficient photocatalytic overall water splitting

Abstract Photocatalytic overall water splitting (OWS) can convert solar energy into hydrogen (H 2 ) and oxygen (O 2 ), which is significant in reducing the reliance on fossil fuels. Constructing S‐scheme heterojunctions is an effective method for facilitating charge transfer, but the huge interfacial charge transfer barrier poses a challenge to advance the efficiency of photocatalytic OWS. Here, a low‐interfacial barrier Ce‐S bond‐enhanced Mo‐doped ZnIn 2 S 4 /oxygen‐deficient CeO 2 (Mo‐ZIS/O V ‐CeO 2 ) S‐scheme heterojunction photocatalyst was designed via a doping‐defect coupling strategy. The abundant unsaturated S atoms generated by doping Mo atoms in ZnIn 2 S 4 combine with the unpaired electrons on the Ce atom in O V ‐CeO 2 , forming the interfacial Ce‐S bonds, which induce a 43% decrease in carrier transport activation energy and a 2.1‐fold increase in build‐in electric field intensity compared to ZIS/O V ‐CeO 2 . Reduced carrier transport activation energy and increased built‐in electric field intensity provide a strong driving force for charge separation following the S‐scheme pathway. Benefiting from the interfacial Ce‐S bonds and the S‐scheme transfer path, Mo‐ZIS/O V ‐CeO 2 exhibits H 2 and O 2 evolution rates of 512.7 and 256.3 μmol g −1 h −1 , respectively, along with a solar‐to‐hydrogen efficiency of 0.14%. This study proposes an innovative insight into developing and constructing S‐scheme heterojunction photocatalysts with efficient charge migration interfaces.