Influence of Ni2+ ions on the structural, morphological, photoluminescence, photo-catalytic and anti-bacterial studies of Cd0.9Zn0.1S nanostructures

Abstract

The present investigation reported the controlled synthesis of Cd 0.9 Zn 0.1 S and Cd 0.89 Zn 0.1 Ni 0.01 S nanostructures by simple chemical co-precipitation route. The XRD analysis confirmed the cubic structure of CdS on Zn doped CdS and Zn, Ni dual doped CdS without any secondary/impurity phases and no alteration in CdS cubic phase was noticed by Zn/Ni addition. The shrinkage of crystallite size from 69 to 43 Å and the variation in lattice constants and micro-strain were described by the addition of Ni and the defects associated with Ni 2+ ions. Microstructural and optical studies of the prepared films were carried out using scanning electron microscope (SEM), UV-visible spectrometer and photoluminescence (PL) spectra. The enhanced optical absorbance in the visible wavelength and the reduced energy gap by Ni substitution showed that Cd 0.89 Zn 0.1 Ni 0.01 S nanostructures are useful to improve the efficiency of opto-electronic devices. The functional groups of Cd-S/Zn-Cd-S/Zn/Ni-Cd-S and their chemical bonding were verified by Fourier transform infrared (FTIR) studies. The elevated visible PL emissions such as blue and green emissions by Ni addition was explained by decreasing of crystallite size and generation of more defects. Zn, Ni dual doped CdS nanostructures are identified as the probable an efficient photo-catalyst for the degradation of methylene blue dye. The liberation of more charge carriers, better visible absorbance, improved surface to volume ratio and the creation of more defects are accountable for the current photo-catalytic activity in Zn/Ni doped CdS which exhibited better photo-catalytic stability after sex cycling process. The better bacterial killing ability is noticed in Ni doped Cd 0.9 Zn 0.1 S nanostructure which is due to the collective effect of lower particle/grain size and also higher ROS producing capacity.

Experimental and DFT studies of structural and optoelectronic properties of CdS, Zn doped CdS, and (Zn-Ni) co-doping CdS nanomaterials

“…For Zn-doped CdS, the value of the gap increases to 2.49 eV, and it is close to the value obtained by Zellagui et al for the same Cd 0.7 Zn 0.3 S alloys [63]. When adding the Ni to CdZnS material, the band gap decreases to 2.30 eV; the same behavior was observed by Raju et al [57]. They report a band gap reduction to 2.36 eV when a concentration of Ni equal to 1% is added into Cd 0.9 Zn 0.1 S alloys.…”

“…This result has been observed experimentally, as shown in section 3.4. A remarkable shift of the absorption through the higher wavelength region has been observed by P. Raju et al in their work [57]. They found that a nanostructure composition of Cd 0.89 Zn 0.1 Ni 0.01 S possesses a strong optical absorption for the lower wavelength, which enhances the optical absorbance in the visible wavelength, therefore showing that this nanostructure material improves the efficiency of optoelectronic devices.…”

“…The spectra reveal a high absorption in the entire UV region and a part of the visible region, and Cd 0.97 Zn 0.03 S, Cd 0.96 Zn 0.03 Ni 0.01 S thin films exhibit a higher broad absorption. The optical properties of CdZnNiS nanostructures were examined by Raju et al [57]. They found similar results for UV wavelength.…”

“…Senthil et al found a similar reduction in the band gap [64]. When adding Ni to CdS, the Ni2+ cation creates a free carrier absorption, and the band gap shrinks [57].…”