A novel Bi _1.5Zn _1-xCu _xTa _1.5O ₇ photocatalyst: Water splitting properties under visible light and its electronic structures

A novel series of Bi _1.5Zn _1-xCu _xTa _1.5O ₇ (Cu-α-BZT) photocatalyst with pyrochlore structure was synthesized by the method of solid-state reaction (SSR) and the electronic structures were calculated based on DFT method. Phase structures, morphologies, optical properties, energy level and specific surface areas of the products were characterized. Pure α-BZT showed a considerable photocatalytic activity under UV irradiation. Furthermore, photocatalytic performance of α-BZT was improved by the method of Cu doping. UV-vis spectra of sample Bi _1.5Zn _1-xCu _xTa _1.5O ₇ (Cu-α-BZT) showed a red shift which made it possible for visible light responding. It was found that Cu-α-BZT exhibited its optimalizing activity at the doping amount (x) of 0.01 in molar ratio. Effects of the Cu-doped on the photocatalytic activities of the catalysts were analyzed by DFT calculation. New band gap in the visible light range was obtained by copper doping, which was attributed to the transition from the donor level resulting from the Cu impurity to the conduction band of α-BZT. The Cu 3d orbital was calculated to be the main contribution to the narrowing of band gap.