TiO2 nanocrystal incorporated with CuO and its optical properties

Ngoc Tai Ly, Thanh Van Hoang, Thi Hong Le Ngo, Van Chien Nguyen, Dang Thanh Tran, Hung Manh Do, Dinh Lam Vu, Xuan Nghia Nguyen, Thi Hoa Dao, Quang Huy Le, Minh Hong Nguyen and Van Hong Le

Abstract

TiO₂ nanocrystal doped with Cu has been fabricated by wet chemical processing. The obtained results of x-ray diffraction, optical absorption in the UV–Vis bands and luminescence spectra have shown that Cu has substituted Ti in the structure of TiO₂ anatase phase when the Cu concentration is about 8 at%. In the case of larger Cu concentrations the copper oxide appeared and increased with increasing Cu concentration. The samples doped with Cu strongly absorb the visible light (400–900 nm) and their absorption edge shifts to the longer wavelength in dependence on the Cu concentration. The absorption in the visible light band is attributed to transitions between the impurities levels of Cu created in the energy band gap of TiO₂. In addition, an absorption shoulder above 800 nm is observed and supposed to be related with the absorption of CuO. The experimental results prove that the TiO₂ anatase doped with Cu is suitable for hydrogen generation by photocatalytic water splitting under sunlight