Influence of CuO loading on dispersion and reduction behavior of CuO/TiO2 (anatase) system

Abstract

In this paper, Brunomer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR) are used to investigate the interactions between CuO and the TiO₂ (anatase) support, in samples prepared by impregnating the TiO₂ support with an aqueous solution of Cu(NO₃)₂·6H₂O. The results indicate that the surface structure of the TiO₂ support has not been changed by supported CuO, and the dispersion capacity of CuO is about 6.98 Cu²⁺ nm (TiO₂)⁻². The structure of the supported copper oxide species is strongly dependent on the amount of CuO loaded. At low CuO loading, only a highly dispersed surface CuO species is formed on the support and when the CuO loading exceeds its dispersion capacity, crystalline CuO is formed as all the vacant surface sites of the TiO₂ support are occupied by Cu²⁺ ions. In addition, it is found that both the reduction behavior and the crystalline-structure transition of the TiO₂ support are related to the interactions between TiO₂ and CuO.