S-Doped rGO-Enwrapped Magnetically Porous NiFe2O4/CuS Heterojunction: An Efficient Z-Scheme Nano-Photocatalyst for Visible-Light-Driven Tetracycline Degradation and 4-Nitrophenol Reduction

Abstract

The photocatalytic degradation of economically hazardous compounds has been thoroughly researched with the aid of numerous photocatalysts and techniques. The efficient degradation and removal of lingering contaminants from the aquatic environment are still difficult to accomplish. Hereby, we present a sulfur-doped reduced graphene oxide (SrGO) enwrapped magnetic porous nickel ferrite (NiFe2O4)/copper sulfide (CuS) nanocatalyst (SrGO/NiFe2O4/CuS:GNFC) constructed through a facile solvothermal-reflux route. Under exposure to visible light, the fabricated GNFC photocatalyst exhibits outstanding catalytic activity for the photodegradation of tetracycline hydrochloride (TCH) and photoreduction of 4-nitrophenol (4-NP). Diverse analytical techniques were used to characterize the fabricated nanomaterials. In terms of photocatalytic activity, GNFC-13 outperforms all other nanocatalysts in eliminating model pollutants. According to our findings, 94.39% of TCH (80 ppm) can be degraded within 90 min, and 90.62% of 4-NP (30 ppm) can be reduced within 120 min by the GNFC-13 nanohybrid, which is significantly better than that of pristine and doublet nanomaterials, respectively. The explanations for the improved photocatalytic efficiency of GNFC nanocatalysts are due to the porous structures of the magnetic NiFe2O4 and the SrGO surface, which can offer a lot of adsorption sites and, therefore, advantageous for the adsorption enrichment of harmful pollutants. Additionally, in situ photocatalytic degradation and adsorption enrichment working together synergistically may lead to improved pollutant removal efficacy. The Raman and XPS analytical techniques verified the formation of SrGO in the GNFC nanocomposites. The free-radical trapping studies, terephthalic acid test, nitroblue tetrazolium test, and electron spin resonance test disclosed that holes (h+), hydroxy radicals (·OH), electrons (e–), and superoxide radicals (·O2–) are cardinal reactive species in the photocatalytic system. A Z-scheme charge transfer channelization mechanism of the as-produced photocatalyst is explained in light of the various experimental findings. The developed Z-scheme system has led to the increase of catalytic activity due to the effective photoinduced carrier separation, wider photoabsorption range, high hole oxidation capacity, and high electron reduction power. In addition, the GNFC photocatalyst ability to catalyze TCH and 4-NP shows no discernible decline even after five recycles. Moreover, the GNFC nanocatalysts are magnetically detachable for recycling. Thus, this study reveals that the as-obtained GNFC nanocatalysts have an excellent prospect for environmental remediation of toxic pollutants.