Electrochemical properties of NiO–Ni electrocatalyst synthesized via solution combustion for methanol oxidation in alkaline media

Abstract

Transition metal oxides have been recently considered as the anode catalyst in direct methanol fuel cells to reduce the anodic overpotential of methanol electrooxidation in alkaline media. In this work, the NiO–Ni catalyst is synthesized via solution combustion synthesis process to reach an appropriate nanomorphology with high effective surface area and electrocatalytic activity. The influence of the fuel type (glycine and urea) and the fuel to oxidizer (F/O) ratio are investigated. The composition and phase analysis, crystallite size, particle size, specific surface area, and morphology of the nanoparticles are assessed. Moreover, electrochemical characteristics of the products are evaluated. The catalytic activity of the product towards methanol oxidation is found to vary with the fuel type and F/O ratio. The dependence of the oxidation current on the adiabatic temperature and morphological characteristics of the product is discussed. It is found that solution combustion synthesis is a confident technique that provides a considerable improvement in catalytic performance. Moreover, it is concluded that samples with dominant NiO show lower onset potential and higher current density. Synthesis by glycine in the most explosive condition (i.e., F/O = 0.83) results in more desirable catalytic activity.