Nickel-molybdenum-niobium metallic glass for efficient hydrogen oxidation in hydroxide exchange membrane fuel cells

The cost of fuel cell systems can be largely reduced by developing hydroxide exchange membrane fuel cells (HEMFCs) based on platinum group metal-free (PGM-free) catalysts. However, the sluggish hydrogen oxidation reaction (HOR) in alkaline electrolytes forces HEMFCs to use higher PGM loadings at the anode than proton exchange membrane fuel cells to sustain the desired power densities. Here we report nickel-molybdenum-niobium metallic glasses as PGM-free HOR catalysts. The optimal Ni52Mo13Nb35 metallic glass exhibits an intrinsic exchange current density of 0.35 mA cm(-2), outperforming that of a Pt disk catalyst (0.30 mA cm(-2)). This catalyst also shows remarkable robustness in alkaline electrolyte with a wide stability window up to 0.8 V versus the reversible hydrogen electrode. When used as the anode, this catalyst enables power densities of 390 mW cm(-2) in H-2/O-2 fuel cells and 253 mW cm(-2) in H-2/air fuel cells, and shows negligible performance degradation over 50 h and 30 h, respectively.

Automated summary

The cost of fuel cell systems can be greatly reduced by developing hydroxide exchange membrane fuel cells (HEMFCs) based on platinum group metal-free (PGM-free) catalysts. Nickel-molybdenum-niobium metallic glasses are reported as PGM-free hydrogen oxidation reaction (HOR) catalysts, which demonstrate excellent catalytic performance and stability in alkaline electrolyte. They enable high power densities in H-2/O-2 and H-2/air fuel cells with negligible performance degradation.