Revealing an efficient copper oxide nanoparticle catalyst for the reduction of the hazardous nitrophenol: experimental and DFT studies

Abstract

The accumulation of hazardous nitrophenols generated from industrial wastewater necessitates every possible scientific collaboration to help protect our ecosystem. To participate in this increasingly pressing matter, we provide a synthesized crosslinked vinyl polymer loaded with copper oxide nanoclusters as a high-performance catalyst for the reduction of 4-nitrophenol to 4-aminophenol. The catalyst was synthesized via free radical polymerization using divinylbenzene (DVB) as the monomer. The resulting polymer served as a support matrix for copper oxide nanoparticles (CuO NPs). The structural characteristics of the synthesized composites were analyzed for their properties using FTIR, TGA, XRD, TEM, and BET for surface area measurements. The results confirm that copper oxide nanoparticles (CuO NPs) were uniformly distributed across the poly(DVB) surface with no aggregation. BET analysis revealed a microporous structure with a defined surface area of 90.0928 m² g⁻¹. When employed as a heterogeneous catalyst in the hydrogenation of 4-nitrophenol (4-NP), the composite achieved a reaction rate constant of 0.45 min⁻¹ and a half-life of 1.45 min. Notably, the catalyst could be easily recovered from the reaction mixture and reused for four consecutive cycles without significant loss in activity. DFT calculations were carried out to elucidate the underlying reduction mechanism of nitrophenol.