Unveiling the impact of the mpg-C3N4@Pa@Ni nanocomposite in the reduction of nitroaromatic derivatives by comparative solvent-free methods†

In this research, the impact of the mesoporous graphitic carbon nitride–papain–nickel (mpg-C₃N₄@Pa@Ni) nanocomposite in the reduction of hazardous nitroaromatic derivatives was investigated under solvent-less and solvent-free conditions. The mpg-C₃N₄@Pa@Ni composite was synthesized in four steps; synthesizing bulk and mesoporous g-C₃N₄, and functionalization with 1,3-dibromopropane, papain, and Ni nanoparticles. Papain was found to be a suitable composite material due to its ability to form covalent and coordination bonds with the substrate and Ni. Several solvent-free and solvent-less methods, including using mortar and pestle, ball mill, microwave, and magnetic stirrer, were employed to investigate the reduction of nitroaromatic compounds due to their fast, simple, and economical green nature. The synthesized nanocomposite demonstrated high efficiency rates in reducing toxic nitroaromatic compounds ranging from 80–98.6%. Structural confirmation of the mpg-C₃N₄@Pa@Ni nanocomposite was carried out using various techniques such as Fourier-Transform Infrared spectroscopy (FT-IR), N₂ adsorption analysis (BET), Field Emission Scanning Electron Microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray Diffraction spectroscopy (XRD), and Thermogravimetric Analysis (TGA). Furthermore, the mpg-C₃N₄@Pa@Ni nanocomposite showed promising recoverability without significant decreases in efficiency for up to eight cycles, indicating its potential as a sustainable and efficient catalyst. The synthesis of mpg-C₃N₄@Pa@Ni nanocomposite and its efficient performance in reducing hazardous nitroaromatic compounds pave the way for a sustainable and environmentally friendly alternative to traditional methods.