Oxalate Assisted Growth of Hybrid Nickel Cobalt-Based Nanostructures for Hydrogen Generation Via Urea Oxidation

Abstract

Hybrid mixed transition metal oxides nanostructures as spinal act as promising electrode materials for energy-related applications. In the present work, a design and synthesis of mixed metal oxide nanostructures have been done by increasing the nickel content in the crystal structure of Co3O4 spinel by using template-assisted oxalate route via conzventional coprecipitation method for syntheses. Selectively controlling the Ni: Co ratio will result in a significant change in the morphology of the nanostructures. Further, kinetically controlled thermal decomposition of nickel and cobalt oxalate precursors results in the formation of anisotropically aligned ultrafine nanoparticle self-assembly to form nanocubes and nanorods. Whereas the mixture of nickel-cobalt oxalate precursor after decomposition led to the formation of nanoparticles assembly that is interconnected and hierarchically arranged to form nanosheets that align themselves in a particular orientation to give a three-dimensional micro flower structure. This hybrid structure with increased porosity and higher exposed active sites acts as an efficient electrocatalyst to promote water and urea oxidation in alkaline media. The hybrid catalyst shows overpotential of 300 mV and -190 mV towards water oxidation in alkaline media with excellent stability for 24 h. Similarly, during urea oxidation, the significant loss in the potential to 1.31 V can be seen to achieve the current density of 10 mA/cm2 compared to the potential required in urea-free electrolysis. So, this work provides better insights for tuning snd designing the hybrid structures and regulating their morphological characteristics for enhanced catalytic performance.