On the essential role of current density in electrocatalytic activity of the electrodeposited platinum for oxidation of ammonia

摘要

Fabrication by electrolytic deposition of platinum (Pt) electrocatalyst provides a promising alternative for oxidation of ammonia. This work investigated the role of current density in the electrocatalytic activity of the prepared Pt electrocatalysts by cyclic voltammetry and surface characterization. The Pt loading amount is determined by inductively coupled plasma. Results demonstrated that, the electrodeposited Pt has a much higher electrocatalytic activity than the pure Pt electrode due to the high electroactive surface area of the Pt deposit. The electrocatalytic activity of the Pt catalyst is improved with the increase of the Pt loading. Moreover, the electrocatalytic activity of Pt increases with the depositing current density which results in an increasing Pt loading amount. The depositing current density also affects the surface morphology of the prepared Pt. The high depositing current density generates small Pt particles at a nanometer scale, or sheet-like dendritic structure. However, the low current density leads to large Pt particles at several hundreds of nanometer with a relatively smooth morphology. The Pt electrocatalyst with the former morphological feature exhibits a higher electrocatalytic activity than the later due to the higher electroactive surface area.