Hydrothermal synthesis of visible light-sensitive conduction band-controlled tungsten-doped titanium dioxide photocatalysts with copper ion-grafts

Abstract

We prepared titanium dioxide (TiO2) photocatalysts sensitive to visible light, namely copper(II) [Cu(II)]-grafted tungsten and gallium co-doped TiO2 (Ti1-3xWxGa2x O2, x value is up to 0.12), based on the concept of narrowing the band gap of TiO2 by positively shifting its conduction band (CB) edge to a lower energy level and the catalytic multi-electron reduction of oxygen by Cu(I) ions [H. Yu, H. Irie, K. Hashimoto, J. Am. Chem. Soc, 132, (2010)]. Using this approach, the optical band-gap energy of TiO2 was decreased to ∼2.8eV, and band-gap narrowing was confirmed by measuring the action spectrum for oxygen evolution from water in the presence of iron ions [Fe(III), from FeCl3]. The Cu(II)-grafted Ti1-3 xWxGa2 x O2 (x = 0.12) photocatalyst effectively decomposed 2-propanol to carbon dioxide (CO 2) via acetone under visible light (400-530 nm, 1 mW/cm2) with a CO2-generation rate of 0.30 μmol/h. Grafting Cu(II) ions after the hydrochloric acid treatment of Ti1-3 xWxGa2 x O 2 (x = 0.12) increased the CO2-generation rate to 0.40 μmol/h. ©2013 The Ceramic Society of Japan. All rights reserved.