Achieving Efficient Hydrogen Evolution of CNT@Ag@ZnIn2S4 Photocatalyst Under Visible Light by Regulating H─S Antibonding Orbital Occupancy via Ag

Zinc indium sulfide (ZnIn 2 S 4 , ZIS), a visible-light-responsive photocatalyst, has garnered significant attention due to its facile synthesis, high stability, suitable band gap, and abundant active sites. This study innovatively constructed a CNT@Ag@ZIS tubular structure, introducing Ag mediators as electron donors at the CNT-ZIS interface. Results demonstrate that the Ag mediators establish clear interfacial contact with both hexagonal ZIS and CNT. Consequently, ZIS exhibits markedly enhanced photocurrent response and improved separation efficiency of photogenerated charge carriers. The catalyst achieved a remarkable hydrogen evolution rate of 18.44 mmol g −1 h −1 , representing an 8.7-fold enhancement over pristine ZIS. The study revealed that Ag, with its high Fermi level, facilitates interfacial electron transfer to ZIS. This induces a downshift of the p-band center (3p orbitals of S) in ZIS, simultaneously prolonging the H─S bond length and increasing the antibonding orbital occupation. This electron restructuring creates electron-rich S (2+δ)− active sites, substantially lowering the H 2 desorption energy barrier. Thus, the surface reaction kinetics of the sulfide are optimized through a regulation strategy targeting antibonding orbitals.