Significantly Enhanced Photoluminescence Performance of Ni x S y (NiS and Ni9S8)/ZnO Nanorods by a Hydrothermal Method

This paper reports on a near zero band gap semiconductor, Ni x S y , which significantly enhances the photoluminescence (PL) performance of ZnO nanorods. The structural, morphological, and optical properties of the composites were characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet–visible spectroscopy (UV–vis), PL spectrometry, etc. The PL patterns at an excitation wavelength (λex) of 325 nm revealed that the 10% Ni x S y /ZnO nanorod (10NZNR) composites displayed the highest emission intensity in the region of 420–630 nm. The relationship between the emission intensity of ZnO and the concentration of Ni x S y demonstrated that the PL intensity of NZNRs initially increased (10%). According to PL spectra at different excitation wavelengths and PL excitation (PLE) spectra, the visible emission of Ni x S y /ZnO nanorod (NZNR) composites can only be excited by light with energy greater than that of the band gap. Studies of the morphological structures and PL behaviors of NZNR composites have illustrated that Ni x S y considerably enhances the visible emission of ZnO by regulating its morphology and structure. An appropriate mechanism by which Ni x S y enhances the PL performance of ZnO has been proposed.