Photocatalytic hydrogen production over CuO-modified titania

Abstract

Efficient hydrogen production and decomposition of glycerol were achieved on CuO-modified titania (CuO–TiO 2) photocatalysts in glycerol aqueous solutions. CuO clusters were deposited on the titania surface by impregnation of Degussa P25 TiO 2 powder (P25) with copper nitrate followed by calcination. The resulting CuO–TiO 2 composite photocatalysts were characterized by X-ray diffraction (XRD), UV–visible spectrophotometry, X-ray photoelectron spectroscopy (XPS), N 2 adsorption–desorption, transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. The low-power ultraviolet light emitting diodes (UV-LED) were used as the light source for photocatalytic H 2-production reaction. A detailed study of CuO effect on the photocatalytic H 2-production rates showed that CuO clusters can act as an effective co-catalyst enhancing photocatalytic activity of TiO 2. The optimal CuO content was found to be 1.3 wt.%, giving H 2-production rate of 2061 μmol h −1 g −1 (corresponding to the apparent quantum efficiency (QE) of 13.4% at 365 nm), which exceeded the rate of pure TiO 2 by more than 129 times. The quantum size effect of CuO clusters is deemed to alter its energy levels of the conduction and valence band edges in the CuO–TiO 2 semiconductor systems, which favors the electron transfer and enhances the photocatalytic activity. This work shows not only the possibility of using CuO clusters as a substitute for noble metals in the photocatalytic H 2-production but also demonstrates a new way for enhancing hydrogen production activity by quantum size effect.