Enhanced interfacial charge transfer on strain-induced 2D-1D/MoS2-TiO2 heterostructures for electrochemical and photocatalytic applications

Abstract

Two-dimensional (2D)/one dimensionsal (1D)-MoS2/TiO2 heterostructures have proven to be potent for photocatalytic applications. Enhancement of a heterostructure’s photocatalytic activity may be influenced by the accumulation of strain at the interface, which affects the interfacial interaction. Keeping this in mind, the present paper reports strain-accumulated interfacial modification of 2D/1D-MoS2/TiO2 heterostructures for the enhancement of photocatalytic activity. Two different synthesis methods, namely the hydrothermal and chemical vapor deposition (CVD) methods, are used for the growth of MoS2 on TiO2 nanostructures. Micro-Raman spectroscopy reveals that strain is accumulated at the interface of the growth of the MoS2 over the TiO2 nanostructures. It is further revealed that the MoS2/TiO2 heterostructure synthesized by the CVD method induces compressive strain. Also, the heterostructure synthesized by the hydrothermal method induces tensile strain that modifies the charge separation at the interface, which is further confirmed by x-ray photoelectron spectroscopy (XPS). Moreover, ultraviolet photoelectron spectroscopy (UPS) reveals upward band-bending in the MoS2/TiO2 heterostructure synthesized by the hydrothermal method. Similarly, the heterostructure synthesized by the CVD method shows downward band-bending that leads to improved charge separation at the interface. The modified interfaces of the heterostructures are further studied for electrochemical measurements using cyclic voltammetry (CV) and photocatalytic activity by degradation of a model compound.