Preparation of Oxygen Deficient Black Titania for Visible Light Assisted Hydrogen Production

Abstract

Black TiO2 is defects engineered material to enhance optical properties. However, in spite of the remarkable improvement and extent optical absorption to visible light, it is failed to demonstrate expected photocatalytic activity due to the presence of a number of recombination centers. In this report, reduced black TiO2 is prepared by a new approach which is the controlled magnesiothermic reduction under a 5% H2/Ar atmosphere. After reduction, surface defects are produced such as oxygen vacancies, surface lattice disorder, and hydrogenation and, as a result, band structure also changed. The prepared material possesses an optimal band structure, surface defects, oxygen vacancies, and charge recombination centers and exhibit dramatically enhanced optical absorption in the visible and infrared region. The combinations induce synergistic effects to make black TiO2 material possible to show an outstanding hydrogen production ability in the methanol-water system in the presence of Pt as a co-catalyst. The material shows remarkable stability and shows the maximum hydrogen production rates are 43 mmol h-1 g-1 and 440μmol h-1 g-1 under the full solar wavelength range of light and visible light, respectively, and these are remarkably enhanced values than previously reported black TiO2 materials. ⓒ 2017 DGIST