Synthesis And Capacitive Performance Of TiO₂ Nanotube Arrays On Si Substrate

Supercapacitor is widely applied in various fields owing to its great power density, long cycle life, green environmental protection and other advantages.With the development of information technology, high-end electronic equipments develop into the miniaturization and require the power equipment with the small size and high power density. So the investigators pay more and more attention to the micro MEMS supercapacitor. Low energy density is a defect of the micro supercapacitor and limits its application in practice.Therefore, improving the energy density of the micro capacitor becomes an important research direction. This paper explores the research of electrode composite material on silicon wafer for the MEMS supercapacitor. Firstly, we explore and search for the optimum condition of the anode oxidation of titanium film for TiO₂ nanotube arrays on silicon substrate. Secondly, we deposit oxide materials（NiO） on TiO₂ nanotube arrays by chemical deposition method. Finally,we test its capacitance performance. The main contents are as follows:（1） We discuss the key experimental conditions such as electrolyte concentration, oxidation voltage in the experiment of anode oxidation of titanium film on silicon substrate. By comparison with the experimental results,it is concluded that low voltage of 0.5 V and low concentration of 0.05 wt % of HF solution is more suitable for anodic oxidation of titanium films. We achieve the tightly and orderlyTiO₂ nanotube arrays on silicon substrate. Optimize the applied voltage, the dense TiO₂ nanotube with diameters ranged from about 100 to 270 nm are fabricated. Finally, we test the adhesion between the titanium film and the silicon dioxide to ensure the preparation of TiO₂ nanotube arrays on the silicon substrate.（2） We obtain the NiO/TiO₂ composite material by depositing NiO on TiO₂ nanotube arrays with chemical synthesis methods and then study its capacitance performance. Firstly, the experiment is deposited metal nickel on nanotube arrays using the method of electroless plating nickel. Secondly, we achieve the NiO/TiO₂ composite material by drying and heat treatment the sample. Observing the SEM figure, we know that the thickness of the nanotube wall is increasing and the nanotube surfaces are coverd with large areas of NiO particles. In the test of capacitance performance, the CV graph appears obvious oxidation and reduction peaks. The specific capacitance of NiO/TiO₂ composite material is 370 uF·cm-2at the current density of 0.01 mA·cm-2. After a cycle of1000 times, the specific capacitance retention is 81%.（3） In order to effectively increase the energy density of MEMS supercapcacitor, we design a new three-dimensional interdigital electrode solid MEMS supercapcacitor based on NiO/TiO₂ composite material. In the whole structure, we cover the PVA-KOH-KI solid polymer gel electrolyte. We test theperformance of the supercapacitor through two electrodes system. The papers give the detailed preparation process of the solid MEMS supercapacitor.Nest we will optimize and validate the experiment to improve the performance of the condenser.