Enhanced photoluminescence and photocatalytic performance of Mn and Co simultaneously doped ZnS nanostructures by co-precipitation method
摘要
In the current work, the fabrication of ZnS, Zn0.96Mn0.04S, Zn0.94Mn0.04Co0.02S, and Zn0.92Mn0.04Co0.04S nanostructures was carried out using a simple chemical co-precipitation method. The cubic structure of the synthesized samples without any additional impurities was verified via X-ray diffraction examination, and the basic cubic structure was not changed by either Mn-doping or Mn and Co-doping into the Zn–S lattice. The change in lattice parameters, size (~ 16–21 Ǻ), and the movement of peak position strongly suggest that Mn2+ / Co2+ ions are successfully incorporated into the Zn–S lattice. The enhanced visible light absorption and the induced red shift of the energy gap (~ 3.92 eV – 3.41 eV, ΔEg ~ 0.51 eV) by Co2+ doping in the Zn-Mn-S lattice are helpful for enhancing the photocatalytic behavior and potential optoelectronic device applications. The red shift of the energy gap stimulated by Mn/Co addition is mostly owing to the interaction between the electrons and the alteration in the energy levels and defect generation by doping, and it is explained by the energy level diagram. Doping of Co2+ not only enhanced the luminescence intensity by extending to the visible region but also elevated yellowish-orange emission (~ 571–578 nm), which is highly recommended for designing organic LEDs, solar cells, and spintronic devices. The reduced energy gap for higher light absorption, higher visible light absorption, surface alteration for photo-induced electron–hole pair recombination, and generation of O2• − and OH• radicals are responsible for the improved photocatalytic degradation efficiency (~ 84.8% @ 100 min.) at Zn0.94Mn0.04Co0.02S with better stability even after four cycles.