Integrating thermodynamics towards bulk level synthesis of nano Ni catalysts: a green mediated sol–gel auto combustion method

Abstract

While there are several metal nanocatalysts in hydrogenation reactions, the synthesis and research study of nano nickel are particularly intriguing due to this transition metal's magnetically separable nature. A novel approach for the massive production of nickel nanoparticles has been introduced by integrating a green medium into the conventional sol–gel auto combustion process (IN patent no. 360528). Lemon juice serves the purpose of the green medium, which acts as a solvent and reducing agent for the formation of nickel nanoparticles in solid form. The Ellingham diagram-based thermodynamics of metal oxide was attempted to explain the formation of metal nanoparticles over the metal oxide nanoparticles. X-ray diffraction analysis was used to optimise the reaction conditions for the formation of precise metal nanoparticles. The structure, morphology, and purity of the synthesised materials were investigated using a variety of state-of-the-art techniques. TEM analysis revealed a spherical morphology of nickel nanoparticles with an average particle size of 8.2 nm. Vibrating ample magnetometer data established the ferromagnetic character of the sample. Nanoparticles were found to be an effective catalyst for the reduction of p-nitrophenol and degradation of rhodamine with sodium borohydride acting as a reducing agent. This particular method of synthesis can pave the way for the solid-state production of crystalline nickel nanoparticles with excellent catalytic efficiency.