Kinetic Analysis of the Reduction of 4-Nitrophenol Catalyzed by CeO2 Nanorods-Supported CuNi Nanoparticles

CuxNi100–x (x = 0, 20, 40, 60, 80, and 100) nanoparticles were uniformly grown on the surface of CeO2 by the liquid impregnation method. The as-prepared nanocomposite abbreviated CuxNi100–x–CeO2 was characterized by various techniques including, X-ray powder diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller surface area analyzer, and transmission electron microscopy. The catalytic activity of CuxNi100–x–CeO2 nanocomposites was investigated in 4-nitrophenol (4-NP) reduction reaction. Among the synthesized nanocomposites, Cu60Ni40–CeO2 exhibited the best catalytic activity (rate constant as 0.1654 s–1) with high recyclability for five consecutive runs. The mechanism of the reduction was studied, and the adsorption equilibrium constant of 4-NP (K4-NP) and borohydride (KBH4–) was calculated by using the Longmuir–Hinshelwood model. The energy of activation (Ea) and thermodynamic parameters such as activation enthalpy (ΔH⧧), entropy (ΔS⧧), and Gibbs free energy (ΔG⧧) have also been determined.