Polypyrrole@polyaniline-reduced graphene oxide nanocomposite support material and Cobalt for the enhanced electrocatalytic activity of nickel phosphide microsphere towards alkaline urea oxidation

Abstract Efficient and low-cost materials are highly demanded to improve the sluggish kinetics and stability of direct urea fuel cells for large-scale commercialization. In this study, modification of conventional nickel phoaphide (NiP) by cobalt doping via the facile solvothermal method and simultaneously dispersing prepared cobalt nickel phosphide (CoNiP) on poly (aniline-co-pyrrole)/reduced graphene oxide (PPy@PANI/rGO) as efficient and low-cost support material via simple ultrasonic/heat mediated dispersion process. The synthesized catalysts were characterized by scanning electron microscopy and an x-ray diffractometer. Furthermore, Cyclic Voltammetry tests were conducted to evaluate the performance of synthesized catalysis towards alkaline urea oxidation. The physical characterization depicts the successful formation of NiP and Co-doped NiP microsphere with a particle size of 4.306 μ m and 2.04 μ m, respectively. In addition, homogeneous distribution of the CoNiP microsphere in the structure of PPy@PANI/rGO support material was achieved. Based on the CV test, the superior electrocatalytic performance of CoNiP@PPy@PANI/rGO electrode material with a potential of 0.414V versus SCE to drive a high current density of 26.92 mAcm −2 , lower onset potential of 0.204 V versus SCE, and higher electrochemically active surface area of 2.08 × 10 –1 cm 2 mg −1 were achieved. Furthermore, the electrochemical activities, kinetics, and stability of CoNiP@PPy@PANI/rGO remarkably outperformed the commercial NiP and CoNiP towards alkaline urea electro-oxidation. Therefore, a novel material, CoNiP@PPy@PANI/rGO, is an excellent candidate for anode electrode material in direct urea fuel cells.