Fabrication and Characterization of Type‐II Heterostructure n:In2O3/p:in‐TiO2 for Enhanced Photocatalytic Activity

The photodegradation rate of anatase TiO2 is enhanced by about 11 times (from 0.0015 to 0.016 min−1) by construction of a type‐II p–n heterostructure of configuration n:In2O3/p:In‐doped TiO2. A simple and cost‐effective two‐stage electrochemical anodization is used for the fabrication of this comparatively stable and recyclable photocatalyst of vertically aligned indium‐doped TiO2 nanotubes with an overlayer of n‐type In2O3 nanoparticles. The modified structural, morphological, compositional, optical, and electrical properties of the TiO2 nanotubes are studied in detail by X‐ray diffraction, X‐ray photoelectron spectroscopy, Rutherford backscattering, field‐emission scanning electron microscopy, reflectance measurements, and electrical conductivity measurements. The enhancement in device performance by the heterostructure is attributable to the tuning of optical bandgap to the visible energy region of solar spectrum, the effective electron–hole pair separation at the potential barrier, and the increase in surface‐to‐volume ratio and effective adsorption area of the photocatalyst by the structural modification with nanoparticles and the nanotube formation. This work focusses on the fabrication of n:In2O3/p:In‐TiO2 type‐II heterostructure by a simple and cost‐effective two‐stage electrochemical anodization to achieve an 11‐fold increase in the photocatalytic efficiency of TiO2. This nanohybrid structure shows successful bandgap tuning to the visible region. The potential barrier at the junction aids in effective electron–hole pair separation.