Facile Fabrication of Indium-Doped TiO2 Via Anodization As Photoanodes for Photoelectrochemical Water Splitting Under Visible Light

Abstract

Directionality of Nanostructured forms of TiO2 prepared through electrochemical anodization as photoanodes in photoelectrochemical (PEC) water splitting benefits the efficient e- and h+ separation. However, a large band gap hinders using such nanostructures in the presence of visible light. Doping with metals can be one of the strategic ways to reduce band gaps. In the present work, single-step anodization of titanium foils in the viscous electrolyte containing different concentrations of indium metal salt is used to fabricate Indium-doped TiO2 nanostructures. The anodization samples are annealed to obtain the photoactive anatase phase of TiO2. As prepared, Indium-doped TiO2 structures are characterized by field emission scanning electron microscope, X-ray diffraction, and UV-Vis light diffuse absorbance spectroscopy. PEC water splitting activity of Indium-doped TiO2 nanostructures is tested in 1 M KOH using a Xe-arc lamp equipped with an AM1.5 G filter under 1 sun. Indium doping enhances the photocurrent, photostability, and charge separation properties compared to the bared TiO2 nanostructures. This work shows that doping the optimum amount of Indium affects the PEC activity of the photoanodes through increased TiO2 lattice defects, and electrical conductivity.