Study of Anode Catalysts and Fuel Concentration on Direct Hydrazine Alkaline Anion-Exchange Membrane Fuel Cells

Abstract

A platinum-free fuel cell using liquid hydrazine hydrate $({\mathrm{N}}_2{\mathrm{H}}_4\cdot {\mathrm{H}}_2\mathrm{O})$(N2H4⋅H2O) as the fuel and comprised of a cobalt or nickel anode and a cobalt cathode exhibits high performance. In this study, the fuel cell performances using nickel, cobalt, and platinum as anode catalysts are evaluated and compared. It is found that fuel cell performance in the case of nickel and cobalt is higher than that in the case of platinum. Further, anodic reactions are discussed by comparing the hydrazine consumption and ammonia generation when cobalt and nickel are used as anode catalyst. Cobalt exhibits a higher rate of decomposition than nickel. Nickel is found to be the most suitable anode catalyst among the above mentioned anode catalysts for this fuel cell. The influence of hydrazine hydrate and KOH concentrations in the fuel on cell performance is also discussed. Cell performance is the highest at a hydrazine hydrate concentration of $4\mathrm{M}$4M and a KOH concentration of $1\mathrm{M}$1M . The maximum power density of the alkaline anion-exchange membrane fuel cell, comprised of a nickel anode and a Co–PPY–C (cobalt polypyrrole carbon) cathode, is $617\mathrm{mW}{\mathrm{cm}}^{-2}$617mWcm−2 .