An efficient tri-metallic anodic electrocatalyst for urea electro-oxidation

Abstract

Tri-metallic MnNiFe alloy nanoparticles with four different Mn:Ni:Fe weight ratios (0.5:2.0:0.5, 0.5:1.0:0.5, 1.0:1.0:1.0, and 2.0:0.5:2.0) on reduced graphene oxide (rGO) supports were synthesized using a one-pot hydrothermal method. The as-prepared catalysts were characterized by X-ray diffraction, inductively coupled plasma-mass spectroscopy, Brunauer-Emmett-Teller analysis, scanning electron microscopy, and transmission electron microscopy, and their catalytic activities were measured by cyclic voltammetry and chronoamperometry. In urea electro-oxidation, the Mn0.5Ni2.0Fe0.5/rGO catalyst exhibited superior electrocatalytic activity compared to Ni/rGO and commercial Ni/C. The Mn0.5Ni2.0Fe0.5/rGO catalyst exhibited a mass activity of 1753.97 mA mg−1 Ni, along with an onset potential of 0.34 V (vs. Ag/AgCl) in 1.0 M KOH and 0.33 M urea solution, which is ~4.2 times and 9.8 times higher than those of Ni/rGO and commercial Ni/C, respectively. Furthermore, a single cell comprising of Mn0.5Ni2.0Fe0.5/rGO catalyst exhibited a peak power density of 30.08 mW cm−2 in 0.33 M urea and 1.0 M KOH at 50 °C. © 2020 Hydrogen Energy Publications LLC