Nucleation Mechanism and Electrocatalysis of Pd NPs onto ITO Electrode in the Electrochemical Deposition Process

Pd nanoparticles(NPs) electrodeposited onto indium tin oxide(ITO) surface were applied to the study of the electrocatalytic activity of ethanol.Firstly,cyclic voltammetry and chronoamperometry were employed to study the deposition mechanism at the initial stage of Pd electrodeposition on ITO.The deposition process was irreversible which was controlled by the diffusion of [PdCl 4]2-,and the diffusion coefficient of[PdCl 4]2-was calculated to be 2.19×10-5 cm2/s.Comparing the current transient data at different potentials with those predicted by the instantaneous and progressive nucleation models under diffusion control,progressive three-dimensional nucleation mechanism was proposed for the nucleation of Pd on ITO at-0.1 V.The mechanism changed to the instantaneous nucleation mode at-0.3 V.FESEM images of the electrodeposits show that the size of Pd NPs is affected by the deposition potential and the deposition period.Secondly,the structure of Pd NPs was analyzed with XRD and the electrochemical behavior on ITO was studied in the solution of 0.5 mol/L H 2SO 4,respectively.Finally,the obtained Pd NPs/ITO were applied in the electrocatalysis of 1.0 mol/L ethanol in alkaline solution,which displayed superior electrocatalytic activity.