Amorphous metallic alloys for oxygen reduction reaction in a polymer electrolyte membrane fuel cell

Amorphous alloyed compounds have been used as electrode materials in electrochemical energy conversion devices. An interesting and important goal for their applications in polymer electrolyte membrane fuel cells is the optimization of the electrocatalysts loading in the membrane electrode assemblies (MEAs). Kinetics of the oxygen reduction reaction (ORR) on Ni ₅₉Nb₄₀Pt_0.6Ru_0.4, Ni ₅₉Nb₄₀Pt_0.6Sn_0.4 and Ni ₅₉Nb₄₀Pt_0.6Ru_0.2Sn_0.2 amorphous catalysts synthesized by mechanical milling were investigated in 0.5M H₂SO₄ at 25°C. The electrocatalytic activity of ink thin-film type electrodes evaluated by cyclic voltammetry (CV) and rotating disk electrode (RDE) showed that the Ni Ni₅₉Nb₄₀Pt _0.6Sn_0.4 amorphous electrocatalyst was the most active from the three electrodes for the cathodic reaction. Fuel cell experiments were conducted at various temperatures at 30 psi for H₂ and at 34 psi for O₂. MEAs fabricated using Nafion® 115 membrane and amorphous Ni₅₉Nb₄₀Pt_0.6Sn_0.4 dispersed on carbon powder was tested as cathode electrocatalyst (1 mg cm-2) in a single polymer electrolyte membrane fuel cell, generating a power density of 156 mW cm-2 at 0.43V and 80°C.