Convenient Construction of Mesoporous Ni-NiO@NC Electrode for Oxidation of Urea
Electrocatalytic urea oxidation(UOR)could be used as an anode reaction for direct urea fuel cells(DUFC).UOR electrocatalysts anchoring Ni and NiO crystal heterojunctions were constructed on mesoporous nitrogenous carbon matrix(NC)by hydrothermal pyrolysis.The peak current density of the alkaline medium UOR anode of the Ni-NiO@NC-500 composite synthesized by the best process was 237 mA/cm2 at 1.67 V,the potential of UOR at 10 mA/cm2 was 1.38 V(vs RHE).12 h CA cycle current density exceeded 80％.Ni-NiO@NC-500 good electrocatalytic activity lies in the formation of heterojunction between Ni and NiO.There was a synergistic effect at the interface.Ni/NiO heterojunction not only provided more UOR active sites,but also facilitated urea adsorption and gas product desorption.In addition,N doping regulated the electron density of the composite and accelerated the electron transfer in the UOR process.Its mesoporous structure was conducive to electrolyte penetration and electron transfer,and its NC improved the stability of the catalyst.Ni-NiO@NC-500 is expected to be an efficient and low-cost UOR electrocatalyst.
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