Study on the enhanced electron-hole separation capability of IrxZn1-xO/Ti electrodes with high photoelectrocatalysis efficiency

Abstract Making full use of low-energy photons and reducing photogenerated carriers' recombination rate have been considered important ways to raise photoelectrocatalysis (PEC) efficiency. In this study, Ir-doped ZnO PEC electrodes were prepared by thermal decomposition method, first principles calculations were used to study the effects of Ir content on the electronic structure and optical properties of IrxZn1-xO coatings, the PEC degradation mechanism of the IrxZn1-xO/Ti electrodes was also tentatively presented. The results indicated that with numbers of Zn atoms replaced by Ir atoms, impurity energy level appeared in ZnO band gap, which reduced the electron transition barriers and increased the number of photogenerated carriers. Besides, IrO2 nanoparticles covered on ZnO nanorods surface, acting as highly efficient electron transfer channels and electrocatalytic active sites, could separate photogenerated electron-hole pairs and enhance PEC performance effectively. PEC performance of IrxZn1-xO/Ti electrodes with different Ir contents under UV irradiation was evaluated by rhodamine B (RhB) removal rate. Compared with pure ZnO electrodes, IrxZn1-xO/Ti ones exhibited much stronger degradation capacity. Specifically, Ir0.09375Zn0.90625O/Ti electrodes showed the highest degradation rate of 99.4%, and a relatively high rate of 95.2% after working 100 h continuously, indicating its excellent long-term stability.