An efficient charge-carrier separation in vanadium-based MXene ternary heterostructure with enhanced photoelectrocatalytic properties
Daniel Muvengei Mwangangi, Thollwana Andretta Makhetha, Jane Catherine Ngila, Langelihle N. Dlamini
Abstract
Tungsten trioxide (WO 3 ) and zinc indium sulfide (ZnIn 2 S 4 ) 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 (V 2 CT x @WO 3 /ZnIn 2 S 4 ). Due to the high electrical conductivity of V 2 CT x MXene, its presence in the heterostructure offers efficient charge transfer kinetics at the interface. Monoclinic WO 3 and cubic ZnIn 2 S 4 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 ZnIn 2 S 4 and 2.55 eV for WO 3 . Photoluminescence and electron impedance spectroscopy demonstrated effective charge separation with low charge transfer resistance by the ternary composite (5 % VWZ). Work functions for ZnIn 2 S 4 (6.68 eV), WO 3 (7.08 eV), and V 2 CT x (8.70 eV) confirmed the creation of an internal electric field at the interface of the semiconductors. Electron migration occurred from ZnIn 2 S 4 to WO 3 due to changes in binding energies as indicated by XPS data confirming S-scheme heterostructure. • S-scheme ternary heterostructure (V 2 CT x @WO 3 /ZnIn 2 S 4 ) demonstrated improved photoelectrochemical properties. • V 2 CT x MXene with high electrical conductivity accelerates efficient charge transfer and separation. • 5 % -V 2 CT x @WO 3 /ZnIn 2 S 4 manifested excellent photoelectrochemical properties with photogenerated electron lifetime of 63.06 ms.