An efficient charge-carrier separation in vanadium-based MXene ternary heterostructure with enhanced photoelectrocatalytic properties

Tungsten trioxide (WO₃) and zinc indium sulfide (ZnIn₂S₄) are among photocatalysts with excellent light absorption properties. However, single photocatalyst suffers from rapid charge carrier recombination. For improved photoelectrocatalytic properties, herein, we report fabrication of a novel S-scheme ternary heterostructure (V₂CT_x@WO₃/ZnIn₂S₄). Due to the high electrical conductivity of V₂CT_x MXene, its presence in the heterostructure offers efficient charge transfer kinetics at the interface. Monoclinic WO₃ and cubic ZnIn₂S₄ were confirmed by X-ray diffraction spectroscopy including crystallite size and micro-strain. Ternary composites demonstrated red shift in light absorption wavelength, with band gap energies as low as 1.58 eV compared to 2.21 for ZnIn₂S₄ and 2.55 eV for WO₃. Photoluminescence and electron impedance spectroscopy demonstrated effective charge separation with low charge transfer resistance by the ternary composite (5 % VWZ). Work functions for ZnIn₂S₄ (6.68 eV), WO₃ (7.08 eV), and V₂CT_x (8.70 eV) confirmed the creation of an internal electric field at the interface of the semiconductors. Electron migration occurred from ZnIn₂S₄ to WO₃ due to changes in binding energies as indicated by XPS data confirming S-scheme heterostructure.