The study of polychromatic luminescence mechanism of ZnO and ZnO/NiS@NiO heterojunction under different alkali source concentrations

ZnO and ZnO/NiS@NiO (ZNN) composites with different precursor concentration ratios (Zn(CH3COO)(2)center dot 2H(2)O: NaOH = 1:1, 1:5 and 1:10) were prepared using a hydrothermal method. The study found that as the concentration of NaOH decreased, the crystallinity of ZnO gradually decreased, the internal defects increase significantly, and the visible light emission intensity in the photoluminescence (PL) spectra also increased. Meanwhile, pure ZnO prepared under the condition of the ratio of 1:1 exhibited completely different defect types of PL characteristics from the products prepared at the ratio of 1:5 and 1:10. The PL emission intensity of ZNN composites prepared by combining various pure ZnO and NiS@NiO has been significantly enhanced, and all ZNN composites exhibited the same type of luminescence characteristics. It is concluded that with the addition of NiS@NiO, the green emission of ZnO is significantly enhanced, and the emission of some defects is shielded. Based on the discussion and analysis, a possible mechanism for the PL process of ZnO and its ZNN composites prepared with different alkali source concentrations was presented.

Automated summary

The study found that decreasing the concentration of NaOH led to a decrease in the crystallinity of ZnO, an increase in internal defects, and an increase in visible light emission intensity. The addition of NiS@NiO significantly enhanced the emission intensity and resulted in the same type of luminescence characteristics for all ZNN composites.