Synthesis of nanostructured microspheres of NiCoO₂ for photocatalytic dye degradation

In this work, NiCoO₂, consisting of nanostructured microspheres, was successfully synthesized via a simple solvothermal method for photocatalytic dye degradation. The synthesized photocatalyst was characterized using X-ray Diffraction (XRD), N₂ adsorption–desorption Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM), energy dispersive X-ray emission (EDX), High-Resolution transmission electron microscopy (HR-TEM), X-ray Photoelectron Spectroscopy (XPS), and UV–Vis absorption spectroscopy techniques. The as-prepared NiCoO₂ exhibited a high specific surface area of 85.046 m² g⁻¹, as revealed in the BET studies. SEM images show that NiCoO₂ possesses nanostructures arranged in three dimensions to form microspheres, allowing easy access to the available high specific surface area for catalytic reactions. The XRD plots indicate a polycrystalline structure of NiCoO₂ with an estimated crystallite size of 13 nm. The optical band gap energy of NiCoO₂ was evaluated to be 2.69 eV, thus enabling it to absorb a large part of the visible light spectrum. High specific area and visible light absorption yield a high photocatalytic efficiency for dye degradation. It exhibited an efficiency of 98.12% within 60 min at a degradation rate of 0.06974 min⁻¹ for the decolorization of Rhodamine B. Thus, the study proposes an inexpensive photocatalyst NiCoO₂, consisting of nanostructured microspheres, for commercial dye treatment technology application.