NiSe2/CdS composite nanoflakes photocatalyst with enhanced activity under visible light

Abstract

Degrading organic pollutants using a photocatalyst under visible light is one of the effective ways to solve the increasingly serious environmental pollution problem. In this work, we have loaded a small amount of NiSe₂ nanoflakes on the surface of CdS using a simple and low-cost solvothermal synthesis method. The samples were characterized with detailed X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), photocurrent, photoluminescence spectrometer (PL), photocatalytic properties, etc. The results show that a 2 mol% load of NiSe₂ increases the rate of degradation of Rhodamine B (RhB) to more than twice the original rate (0.01000 min^-1 versus 0.00478 min^-1). Meanwhile, the sample has excellent stability. The improved photocatalytic properties can be attributed to the face-to-face contact between the nanoflakes, accelerated separation and transfer of photon-generated carriers. This work provides a suitable co-catalyst that can be used to optimize the performance of other photocatalytic materials.

Fig. 1. XRD patterns of CdS and 1 mol%, 2 mol%, 3 mol% NiSe₂ composited CdS.

Fig. 2. (a) SEM images of CdS, (b–f) SEM images, TEM images, EDS mapping images, high-resolution TEM images of 2 mol% NiSe₂ composited CdS.

Fig. 3. (a) XPS spectra of Cd and (b) XPS spectra of S for CdS and 2 mol% NiSe₂ composited CdS, (c) XPS spectra of Ni and (d) XPS spectra of Se for 2 mol% NiSe₂ composited CdS.

Fig. 4. (a) The concentration of RhB under the photocatalytic degradation of different photocatalysts. (b) Degradation rate curve based on the concentration of RhB. (c) Cycle performance of 2 mol% NiSe₂ composited CdS.

Fig. 5. (a) EIS Nyquist plots, (b) transient photocurrent and (c) PL spectrum of CdS and 2 mol% NiSe₂ composited CdS.