Rapid reduction of nitrophenols using reusable magnetic \textit{h}-BN/Ni--NiO nanocomposites

Abstract

The efficient and cost-effective conversion of nitro compounds to amines is crucial for industrial processes and environmental remediation, highlighting the growing demand for earth-abundant metal-based catalysts. In this study, magnetic Ni--NiO nanostructures and their composites with two-dimensional hexagonal boron nitride (\textit{h}-BN) were synthesized via a simple and scalable combustion method. The structural, morphological, and compositional properties of the synthesized materials were systematically investigated using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV--Vis spectroscopy. The catalytic activity of both Ni--NiO and \textit{h}-BN/Ni--NiO nanostructures was evaluated using nitrophenol reduction as a model reaction. The \textit{h}-BN/Ni--NiO nanocomposite exhibited significantly enhanced catalytic performance compared to pristine Ni--NiO, highlighting the synergistic interaction between \textit{h}-BN and Ni--NiO nanoparticles. Notably, the magnetic nature of the Ni--NiO core enabled facile recovery of the catalyst using an external magnetic field, and the composite demonstrated excellent stability and reusability for up to six catalytic cycles with minimal loss of activity. The combination of high catalytic efficiency, magnetic separability, and structural stability positions the \textit{h}-BN/Ni--NiO nanocomposite as a promising candidate for green and sustainable catalytic applications, particularly in environmental remediation.