Abstract

This research examines the influence of two main reduction techniques- hydrogenation and DC plasma on the band gap characteristics of defective titanium dioxide (TiO_2-x). Recognized for its photo-catalytic properties, TiO₂ nano-structures demonstrate improved functionality when subjected to a reduction process. Initially, TiO₂ nanoflakes were fabricated via the hydrothermal method. Then, thermal hydrogenation and DC plasma treatments were independently employed in an Ar/H₂ atmosphere (90/10 vol%) to develop defective TiO_2-x structures. The incident photon to current efficiency (IPCE) spectra of the treated defective TiO_2-x photo-anodes in 0.1 M Na₂SO₄ displayed a notable increase in photo-activity within the UV range, rising from 5% to 35% compared to the pristine TiO₂ nanoflakes. The Tauc plots were also developed for defective TiO_2-x samples based on the IPCE data. The findings indicate the presence of weak band tails, measuring less than 0.2eV, attributed to defect states between valence and conduction bands. Notably, these weak band tails significantly influence the electronic structures of defective TiO_2-x, enhancing their photo-activities up to seven-fold.