Fabrication by electrolytic deposition of Pt–Ni electrocatalyst for oxidation of ammonia in alkaline solution

Electrocatalytic activity of Ni–Pt electrocatalysts fabricated by electrolytic deposition for ammonia oxidation as well as the nucleation mechanism of electrodeposited Pt on Ni substrate was investigated by cyclic voltammetry, potentiostatic current--time transient, electrolytic cell polarization curve measurement and atomic force microscopy techniques. Nucleation of Pt on Ni substrate is time and potential dependent, following a mixed 3-D progressive and instantaneous mechanism. With nucleation and growth of Pt as well as the enhanced uniformity of Pt distribution, the electrocatalytic activity of Ni–Pt electrode is enhanced. The threshold value of applied voltage to oxidize ammonia on the fabricated Ni–Pt electrocatalyst in alkaline solution is 0.55 V, which is comparable to those noble metal-modified Pt electrocatalysts. Furthermore, the ammonia electrolytic efficiency on Ni–Pt electrocatalyst is as high as 75%, which is much higher than that on bright Pt and Pt–Ru electrodes, and is comparable to Pt–Ir electrode. Fabrication of Ni–Pt electrocatalysts by electrolytic deposition provides an economic, high-performance alternative for ammonia oxidation and production of hydrogen.