Probing interfacial charge transfer dynamics in MoS2/TiO2 nanocomposites using scanning Kelvin probe for improved photocatalytic response

Abstract

Layered Molybdenum disulfide (MoS2) is a promising co-catalyst for enhancing the photocatalytic response of titanium dioxide (TiO2). The modified interfacial charge carrier dynamics during work function (WF) modulation due to change in the surface electronic properties of MoS2/TiO2 nanocomposites (NC) plays a major role in enhancement of its photocatalytic activity (PCA). In the present work, MoS2/TiO2 NC with varying content of MoS2 is used for systematic alteration of surface electronic properties of MoS2/TiO2 NC. Scanning Kelvin probe microscopy (SKPM) and Raman spectroscopy are used to probe the interfacial charge transfer mechanism and its role in improving the electron-hole (e-h) pair separation during photocatalysis. The effect of WF modification on the photocatalytic degradation of Rhodamine B (RhB) is investigated by UV-Visible spectroscopy. The obtained results indicate that tailored WF modifies the kinetics involved in the photocatalysis by shifting the Fermi levels of MoS2 and TiO2 due to charge transfer across the interface. It is observed that an optimum level of MoS2 content in the NC based on their morphology and distribution induces better e-h separation leading to high PCA in MoS2/TiO2 NC. This study provides deeper insight into the mechanism of photocatalytic process of hybrid nanostructures.