ITO上电沉积Pd的成核机理及电催化性质

采用循环伏安技术和计时电流技术, 研究了ITO上电沉积Pd的过程, 发现Pd在ITO表面的电沉积是过电位成核且为不可逆的扩散控制过程; 根据Cottrell方程计算得到[PdCl₄]^2-的扩散系数为2.19×10^-5 cm²/s; 根据Scharifker的理论模型, 归一化处理电流-时间曲线, 与理论成核曲线对照, 判断Pd 的成核机理. 通过场发射扫描电子显微镜(FESEM)对Pd 的形貌进行分析, 讨论了沉积电位和沉积时间对Pd纳米粒子形貌的影响. 用X射线粉末衍射(XRD)对Pd纳米粒子进行结构分析, 并在0.5 mol/L H₂SO₄溶液中研究了其电化学性质及在碱性条件下乙醇分子的电催化性质.

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.