Electro-oxidation of ethanol and bioethanol in direct alcohol fuel cells by microparticulated amorphous Ni ₅₉Nb ₄₀Pt _0.6Cu _0.4 and Ni ₅₉Nb ₄₀Pt _0.6Cu _0.2Sn _0.2 alloys

This work has focused on the development of metallic amorphous microparticulated alloys of composition Ni ₅₉Nb ₄₀Pt _0.6Cu _0.4 and Ni ₅₉Nb ₄₀Pt _0.6Cu _0.2Sn _0.2, obtained by mechanical alloying (MA), for use as anodes in direct alcohol fuel cells (DAFCs). The addition of copper modifies the electronic properties of platinum due to its special electronic configuration (3d ¹⁰4s ¹), demonstrating a better performance for ethanol/bioethanol electro-oxidation. Ni ₅₉Nb ₄₀Pt _0.6Cu _0.4 alloy provides higher current densities than Ni ₅₉Nb ₄₀Pt _0.6Cu _0.2Sn _0.2 alloy. In spite of tin significantly improving the tolerance to different adsorbed species such as CO, its presence does not improve the electro-oxidation reaction due to limit the distribution of platinum atoms by the ligand effect, avoiding the final oxidation to CO ₂. In both alloys higher current densities were obtained for bioethanol electro-oxidation than ethanol, due mainly to the presence of acetaldehyde, formic acid and another organic compounds (ppb), which may contribute to improvement of catalytic results.