Facile preparation of mesoporous NiS-coupled Co₃O₄ nanocomposites for photocatalytic reduction of Cr(VI) ions under visible light illumination

Cr(VI) ion deposits in water can negatively affect the ecosystem and people's health. Constructing a reusable and effective photocatalyst defies dominating semiconductors' unstable nature and rapid recombination. Here, with variable NiS contents, new sol-gel nanocomposites of mesoporous NiS-Co3O4 were synthesized. We investigated the photocatalytic performance of NiS nanoparticles (NPs) anchored to mesoporous Co3O4 in the photoreduction of Cr(VI) ions under visible illumination. The structural, textural, and optical features of the synthesized materials were completely characterized by different techniques. The constructed nanocomposites demonstrated mesostructured materials with 133-160 m(2)/g of surface area. Changing the NiS content revealed the diminution in bandgap (Eg) from 2.46 to 1.8 eV and hence Co3O4's ability to absorb visible light was altered. The 2.0 gL-1 of 12 wt% NiS-Co3O4 photocatalyst demonstrated superior photoreduction efficiency of Cr(VI) ions with a photoreaction rate of 0.0583 min(-1) after 50 min of illumination. Moreover, this photocatalyst revealed effective photocatalytic stability and retained 97 % of its original performance after 5 cycles. The enhancement in performance of this NiS-Co3O4 nanocomposite is mainly due to modified light absorption and potent interfacial isolation of charge carriers.