Facile Liquid-Phase Synthesis of a High-Performance Cd-Doped ZnO-Quantum-Dot-Based Photocatalyst

Doping is an effective functional modification method for improving the optical, electrical, and magnetic properties of semiconductors. Here, Cd-doped wurtzite ZnO-quantum-dot (ZQ) zero-dimensional nanomaterials were successfully prepared via liquid-phase synthesis. The experimental results showed that Cd doping can effectively shorten the bandgap, where the optical bandgap range of Cd-doping photocatalysts were 3.31-3.36 eV; in particular, the Cd5-ZQ (Cd contents of 0.5 wt%) sample reduced the bandgap from 3.39 to 3.31 eV compared to that of pure ZQ . This is consistent with the experimental results, where the simulation calculation results indicated the bandgap reduced from 3.107 to 2.912 eV after introducing Cd. Photoluminescence spectroscopy results confirmed the Cd-ion dopants efficiently capture excited electrons and further prolongs the charge lifetime. The degradation of a methylene blue solution under simulated solar light irradiation revealed that the photocatalytic properties of Cd-ZQ nanomaterial with suitable dopant concentration (Cd content 0.5 wt%) was significantly better than those of pure ZQ. The underlying mechanism involves a synergistic effect, and a reasonable and convenient strategy for uprated performance is presented.