Photoinduced Hole Trapping in MoSe₂–MoS₂ Nanoflowers/ZnO Nanosheets S-Scheme Conduit for Ultrafast Charge Transfer during Hydrogen Evolution

Abstract

Paving the way out of sustainable energy applications, one of the most captivating aspirations is development of state-of-the-art catalytic systems for harnessing hydrogen energy. Here, a unique MoSe2–MoS2/ZnO heterojunction with S-scheme-type band alignment has been modeled to elucidate its ascendancy toward PC, EC, and PEC hydrogen generation. Optimized 5 wt % MoSe2–MoS2/ZnO (5MMZ) exhibited 5-fold superior PC H2 production efficiency than bare ZnO, with 58.6% AQY ascribed to augmented solar harvesting and improved photophysical properties as confirmed by optoelectronic and theoretical analysis. Femtosecond transient absorption studies were carried out to provide deeper insights into the photoinduced charge carrier behavioral dynamics. It revealed that the delayed recombination of electron carriers at shallow and deep trap sites with holes was accountable for the higher activity of the 5MMZ heterostructure. XPS and DFT studies ascertained a great deal of correlation between experimental achievements and theoretical predictions as discussed in the reaction mechanism. To determine the diversified scope of MoSe2–MoS2/ZnO heterojunctions in green H2 generation, photo/electrochemical water splitting operations were also performed, which further reinforced the versatility of this kind of metal oxide (ZnO)-bilayered material (MoSe2–MoS2)-type ternary heterostructures.