NiOX-Pt/C nanocomposites: Highly active electrocatalysts for the electrochemical oxidation of hydrazine

NiOx-modified Pt/C nanocomposites are synthesized and investigated for hydrazine electrooxidation in an alkaline electrolyte. The reaction onset potential is significantly reduced in comparison to that of pure Pt/C, owing to the occurrence of a bifunctional mechanism, in which OH species on Ni sites facilitate the oxidation of adsorbed H atoms on the Pt surface. On-line Differential Electrochemical Mass Spectrometry (DEMS) shows that NiOx-Pt/C catalyzes the heterogeneous chemical hydrolysis at open circuit potential, producing H-2 and N-2.Just above the OCP, the H-2 signal in DEMS decreases concomitantly with the increase in faradaic current, due to quantitative H-2 (and Had) electrooxidation on Pt, or due to the deceleration of the overall reaction of hydrolysis. At slightly higher potentials, the N-2 signal further rises, which indicates the onset of complete electrooxidation of hydrazine. In the platinum-oxide region, the H-2 signal increases again and this process is also accompanied by a small ionic signal of NH3, evidencing the occurrence of an incomplete hydrazine electrooxidation route, at least in a minor extent. (C) 2016 Elsevier B.V. All rights reserved.