Study of Pt-free anode catalysts for anion exchange membrane fuel cells

Unsupported transition-metal nanoparticles such as Ni, Co, and NixCoy (Ni0.75Co0.25, Ni0.50Co0.50, Ni0.25Co0.75) were synthesized by the liquid reduction process for application to the anode catalyst of Precious Metal-free Liquid feed Fuel Cells (PM-fLFCs) using hydrazine hydrate (N2H4·H2O) for a fuel. Their electrocatalytic activities were evaluated by rotating disk electrode (RDE), and the mass activity of Ni0.50Co0.50 exhibited higher activity than other catalysts for the anodic oxidation of hydrazine in alkaline solution. The morphology and structure of these catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoemission spectroscopy (XPS). It has been indicated that Ni0.50Co0.50 has a coexistence effect by inhabitation of Co oxidation and significantly improve the electrooxidation of hydrazine. The excellent fuel cell performance, 0.891 V of open circuit voltage and 432 mW/cm2 of high maximum power, was exhibited using Ni0.50Co0.50 catalysts.