Structurally Modulated NiV-LDH with CdMoSe-Quantum Dots: Unlocking the Active Centers at S-Scheme Heterojunctions for Stimulating Photocatalytic H2O2 Production and H2 Evolution

Abstract

Designing and accumulating quantum dots (QD) onto layered double hydroxide (LDH) for the photocatalytic production of H₂ and H₂O₂ is a formidable task. Here, we intended the synthesis procedure of CdMoSe-QD (CMS)-incorporated NiV-LDH (NV) through a facile in situ reflux method and explored the photocatalytic activities of the CMS/NV (CNV) heterostructure. CNV-1 exhibits a large interface contact area and assures excellent interfacial charge transfer ability. Moreover, CNV-1 exhibits outstanding H₂ and H₂O₂ production rates, i.e., 6.4 and 2.5 times higher than that of pristine NV, respectively, due to formation of an S-scheme heterojunction between NV and CMS. Both NV and CMS function as n-type semiconductors and extend photoresponse to visible regions. The CNV-1 composite achieves 1.67% SCC for photocatalytic H₂O₂ generation and 7.36% ACE for photocatalytic H₂ evolution. The excellent activity is ascribed to higher anodic photocurrent, the quantum confinement effect of CMS, large surface-active sites, and delayed recombination of excitons as supported by PL and EIS measurements. Further, the S-scheme mechanism was authenticated through a radical scavenging test and work function, evaluated by UPS measurement. Altogether, this study exemplifies the concepts of designing a CNV heterostructure, which operates via an n–n-based S-scheme mechanism and aims to enhance photocatalytic H₂ and H₂O₂ production.