In this paper,the early stages of nucleation and photoirradiation growth of CeO_(2) thin films have been studied.Cyclic voltammetry,chronoamperometry and scanning electron microscopy were used to analyze the nucleation process of CeO_(2) thin films deposited on the anode with photo irradiation.Experimental results show that the anodic deposition process with photo illumination is controlled by diffusion.Compared with the dark state,photo illumination mainly contributed to increase the current density of the three-dimensional nucleation process,because photo illumination is helpful to create active sites and accelerate the nucleation progress on the surface that a thin ceria film has been formed.Two-dimensional nucleation process mainly exists within the initial 2 s,and then only three-dimensional instantaneous nucleation process continues,which may be the main reason why the thickness of the CeO_(2) film can continue to grow with photo illumination but not in the dark state.Increasing the deposition overpotential can promote two-dimensional nucleation and growth rate,whilst when the potential exceeds 0.65 V,three-dimensional current density decreases.The limiting factor at that time may be the diffusion rate of cerium ions in the solution towards the electrode substrate.
JIN TongzhengJIANG XinyiYANG YumengZHU BenfengLIU JiaoJIANG LiWEI GuoyingZHANG Zhao
The CoWP film with good magnetic performance and corrosion resistance was electrolessly plated from alkaline solution. The technical parameters of the electroless plating system were optimized. When the pH value of electroless plating solution was 11.0 and the reducing agent (NaH2PO2) content was 0.4 mol L 1, the target chemical reactions proceeded in the electroless plating solution smoothly with negligible interference and side effects. CoWP film prepared under optimal deposition condition contained more hexagonal close-packed (hcp) cobalt (ε-Co) of [110] and crystallographic orientation of Co [002]. VSM analysis reveals that the saturation magnetization of the CoWP film is 100～220 Am2 kg 1 and coercivity is (2.87～4.38)×104 A·cm 1. The corrosion behavior of CoWP film in 3.5% NaCl aqueous solution was studied by electrochemical experiments. The results prove that the corrosion resistance of the CoWP film deposited under the optimal depo-sition condition exhibites relatively lower corrosion current of (3.054～3.162)×10 6 A·cm 2. The surface morphology analysis indicates that the film is smooth and composed of regular-shaped crystallites.
