Surface, optical and photocatalytic properties of Rb doped ZnO nanoparticles

The present work describes the synthesis of pure and Rb doped ZnO (ZnO:Rb) nanoparticles by a simple combustion technique. The surface, structural, optical, morphology and photocatalytic activities of the ZnO:Rb nanoparticles were studied with respect to pure ZnO. X-ray diffraction studies confirmed the presence of a hexagonal wurtzite phase of ZnO and a secondary phase Rb2ZnO2 was also observed with increasing content of Rb into the ZnO. Field emission scanning electron microscopy confirmed an irregular shaped morphology for the ZnO:Rb samples. The X-ray photoelectron spectroscopy results confirmed both ZnO and Rb2ZnO2, as a new phase. Time of flight secondary ion mass spectroscopy revealed the homogeneous distribution of the Rb in the ZnO and the enrichment of Rb2ZnO2 at the outside and surface of the particles. In the photocatalytic degradation of RhB dye under natural sunlight irradiation, 97.0%, 20.2%, 16.6%, 15.7% and 12.8% degradation was evidenced for ZnO, Rb 5%:ZnO, Rb 7%:ZnO, Rb 10%:ZnO and Rb 15%:ZnO samples, respectively. The result demonstrated that doping ZnO with Rb affects the recombination process of the electron-hole pairs produced by the photon absorption and consequently influence the photocatalytic activity of ZnO.