Electrochemical Deposition Of Pt Electrodes And Their Electrocatalytic Applications In Ammonia Oxidation

Electro?oxidation of ammonia has great importance in both ecological and energetic aspects. And it depends on the development of catalyst electrodes. In this paper, we prepare catalytic electrodes on the substrates of glassy carbon (GC) and indium tin oxide (ITO) transparent conductive glass by electrochemical deposition. Meanwhile, we investigate the relationship between prepared method and performance of electrodes.Firstly, Pt electrodes are prepared on the surface of glassy carbon substrate through controlling the current density and time of the electrochemical deposition process. Scanning electron microscope (SEM) is used to characterize the morphology and the results demonstrate that it is determined by current density. The low current density generates large spherical Pt particles. However, because of high overpotential which makes deposition under the controlling of diffusion process, the high depositing current densities lead to small Pt particles with sheet?like structure. And the Pt loading amounts are determined by inductively coupled plasma (ICP). Results indicate a low depositing efficiency which is affected by current density and time. The electrocatalytic performance towards ammonia oxidation for the Pt/GC electrodes and their active surface areas are investigated by the cyclic voltammetry (CV). Results show that, depositional condition affects electrocatalytic activity of Pt greatly greatly. The electrocatalytic activity increases with the Pt loading but depends on current density when electrodes have similar amount of Pt. And the results of active surface areas show a comparable trend. Then whether ITO can be used as a substrate is discussed. Pt/ITO electrodes are prepared by potentiostatic deposition. The results of scanning electron microscope (SEM) and energy dispersive X?ray fluorescence spectrometer (EDS) demonstrate that the morphology of Pt is spherical particles dispersing on the surface of ITO with sub?micron size. And the particles have polycrystalline structure which is determined by X?ray diffraction (XRD). Meanwhile, results of cyclic voltammetry (CV) indicate that, Pt/ITO electrode has a superior electrocatalytic activity in ammonia than the pure Pt electrode due to a higher electroactive surface area. However, the bonding force is poor between depositing Pt and substrate. With ultrasound added in depositing, the bonding force and electrochemical stability are proved to have an improvement by SEM and CV.