Combinatorial discovery of Ni-based binary and ternary catalysts for hydrazine electrooxidation for use in anion exchange membrane fuel cells

Ni-based catalysts, binary Ni-M (with M = Mn, Fe, Zn, La) and ternary Ni-Mn-Fe and Ni-Zn-La were investigated for hydrazine oxidation in direct hydrazine hydrate fuel cell anodes by a temperature controlled 16-channel electrochemical combinatorial array. The binary Ni0.8Zn0.2 and Ni0.9La0.1 catalysts are significantly more active than the Ni reference catalyst for hydrazine oxidation. While the best Ni0.8Zn0.1La0.1 ternary catalyst is close to the high active binary catalysts in composition. Additionally, Ni0.6Fe0.2Mn0.2 catalysts also showed high catalytic activity for hydrazine oxidation in alkaline media over standard Ni catalyst. The X-ray diffraction (XRD) analysis indicated that the alloying effect between Ni and added elements improves the catalytic activity for hydrazine oxidation. As a result of the screening tests and our previous research, unsupported binary Ni0.87Zn0.13 and Ni0.9La0.1 catalysts were synthesized by spray pyrolysis and tested in a direct hydrazine hydrate fuel cell MEA (DHFC) producing 486 mW cm−2 and 459 mW cm−2, respectively.