Photoresponsive Activity of the Zn0.94Er0.02Cr0.04O Compound with Hemisphere-like Structure Obtained by Co-Precipitation

In this work, a ZnO hemisphere-like structure co-doped with Er and Cr was obtained by the co-precipitation method for photocatalytic applications. The dopant's effect on the ZnO lattice was investigated using X-ray diffraction, Raman, photoluminescence, UV-Vis and scanning electron microscopy/energy dispersive spectroscopy techniques. The photocatalytic response of the material was analyzed using methylene blue (MB) as the model pollutant under UV irradiation. The wurtzite structure of the Zn0.94Er0.02Cr0.04O compound presented distortions in the lattice due to the difference between the ionic radii of the Cr3+, Er3+ and Zn2+ cations. Oxygen vacancy defects were predominant, and the energy competition of the dopants interfered in the band gap energy of the material. In the photocatalytic test, the MB degradation rate was 42.3%. However, using optimized H2O2 concentration, the dye removal capacity reached 90.1%. Inhibitor tests showed that (OH)-O-center dot radicals were the main species involved in MB degradation that occurred without the formation of toxic intermediates, as demonstrated in the ecotoxicity assays in Artemia salina. In short, the co-doping with Er and Cr proved to be an efficient strategy to obtain new materials for environmental remediation.

Automated summary

In this study, a ZnO hemisphere-like structure co-doped with Er and Cr was prepared and investigated for its photocatalytic applications. The effects of the dopants on the ZnO lattice were analyzed using various techniques. The co-doped Zn0.94Er0.02Cr0.04O compound showed distorted lattice structure and the energy competition of the dopants influenced the band gap energy of the material. The photocatalytic test revealed a 42.3% degradation rate of methylene blue, which could be further enhanced to 90.1% with optimized H2O2 concentration. The results also suggested that (OH)-O-center dot radicals were the main species involved in the degradation process without the formation of toxic intermediates.