Facile synthesis of Co/Ni bimetallic phosphate as electrode material for urea fuel cells: Effect of synthetic strategy on the physicochemical and electrocatalytic behavior

Abstract

Novel bimetallic Co/Ni phosphates were introduced in this work by two different synthetic strategies; reflux (CoNiP-R) and sol–gel (CoNiP-S) methods and evaluated as cheap electrodes for electrooxidation of urea (UEO) in alkaline medium (KOH medium). The as-prepared CoNiP-R and CoNiP-S materials were studied in terms of different physicochemical tools including Field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), transmission Electron Microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and Brunauer, Emmett and Teller (BET) surface area to understand what the effect of the synthetic method on the morphology, crystallinity, and surface area is. These investigations indicate the successful synthesis of smaller particles with higher surface area by sol–gel methodology if compared with the reflux method. The performance of CoNiP-R and CoNiP-S as electrode materials for UEO was evaluated through cyclic voltammetry (CV) at diverse urea contents and various sweep rates in addition to electrochemical impedance spectroscopy (EIS) and chronoamperometric (CA) methods. The synthesized CoNiP-S showed an enhanced UEO if compared with CoNiP-R at various urea doses up to 1.0 mol/l. Besides, the improvement of the obtained charge transfer resistance and current density indicates the increase of electrons generated from UEO.