Influence of Ni on enhanced catalytic activity of Cu/Co3O4 towards reduction of nitroaromatic compounds: studies on the reduction kinetics

In this work, we have investigated the influence of Ni on Cu/Co3O4 towards catalytic reduction of nitroaromatic compounds. For this purpose, Cu, Ni and CuNi alloy nanoparticles supported over Co3O4 are synthesized by a surfactant aided co-reduction method. The Co3O4 support is synthesized via a template-free hydrothermal route. The Co3O4 support and CuNi/Co3O4 nanocatalysts are characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), UV-visible spectroscopy and Brunauer-Emmett-Teller (BET) surface area techniques. The Co3O4 supported CuNi alloy nanoparticles exhibit superior catalytic performance for 4-nitrophenol (4-NP) reduction in comparison to the monometallic catalysts due to synergistic effects. Furthermore, the supported bimetallic nanoparticles demonstrate high recycling ability towards the reduction of 4-NP up to six cycles. To demonstrate the effectiveness of the highly active CuNi/Co3O4 nanocatalyst towards reduction of various nitroaromatics, the catalyst is also used for reduction of 4-nitroaniline, 4-nitrotoluene, 3-nitroaniline, and 2-nitroaniline. The presence of the CuNi/Co3O4 interfaces in the nanocatalyst is believed to be responsible for the high catalytic activity.