Direct observation of photoinduced charge redistribution of WO_3-TiO_2 double layer nanocomposite films by photoassisted Kelvin force microscopy

摘要

The microscopic photoinduced charge redistribution between heterogeneous semiconductor nanofilms of WO_3 and TiO_2 double layers (written as WO_3-TiO_2 nanocomposite films) was directly observed using Kelvin probe force microscopy (KFM) coupled with an UV light source. Under illumination the surface potential morphologies of WO_3-TiO_2 nanocomposite films changed from 162 to 592 mV, which was associated with the photoinduced charge transfer between WO_3 and TiO_2 nanoparticles due to the energy level alignment between them. This improved technique of photoassisted KFM was presented to visualize the photoinduced charge transfer between different semiconductor nanoparticles on microscopic scale.