Catalytic reduction of 4-nitrophenol on the surface of copper/copper oxide nanoparticles: a kinetics study

Abstract

Metal and metal oxide nanoparticles are very suitable for catalytic activities in organic electron transfer processes. Among these, copper is one of the most important materials that have catalytic activity and the synthesis of copper/copper oxide nanoparticles ($$\mathrm{C}\mathrm{u}$$/$${\mathrm{C}\mathrm{u}}_{2}\mathrm{O}$$ NPs) is more cost-effective than other noble metals. In this study, a combination of copper nanoparticles with different degree of oxidation has been synthesized by electrochemical method. The efficiency of synthesized material for the catalytic reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride was studied. The morphology, particle size, and crystalline structure of the synthesized catalyst was studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. The kinetics of reaction was followed by UV–Visible spectroscopy and the effect of different parameters such as initial concentrations of 4-nitrophenol, sodium borohydride and catalyst dosage on the reaction rate was studied. The recyclability of the prepared catalyst was investigated as well. The reaction order of the catalyst dosage was investigated by graphical analysis method. Finally based on Langmuir–Hinshelwood (L–H) mechanism the rate of reaction was modeled.