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Electrochemical Properties And Capacitive Deionization Of Carbon Nanotubes Films

Posted on:2007-05-03Degree:DoctorType:Dissertation
Country:ChinaCandidate:X Z WangFull Text:PDF
GTID:1101360212958142Subject:Radio Physics
Abstract/Summary:PDF Full Text Request
In the 21st century, nanotechnology has been proven to be a new solution to mitigate the world's energy crisis and environment contamination problems. Electrochemical properties of carbon nanotubes have shown unique applications in the fields of energy storage system and water purification.Carbon nanotubes have high conductivity, large surface area and optimal pore size distribution, and have been proposed as electrodes for supercapacitors. On the other hand, the electrochemical capacitor properties of carbon nanotubes make it possible for water purification by capacitive deionization (CDI). Capacitive deionization is a water purification technology with low cost, energy saving, simple and easy operating. It's shown to be crucial significance for the prevention of water pollution, safeguard of people health and continual economy development.In this paper, we have investigated the electrochemical properties, esp. CDI of large-area grown carbon nanotubes and nanofibres composite (CNTs-CNFs) films. The CNTs-CNFs composite films were prepared by low temperature and low pressure chemical vapor deposition (CVD). The main results are as follows:1. The CNTs-CNFs composite films electrodes were prepared by low temperature and low pressure CVD. It has been shown a low cost way to fabricate large area CNTs-CNFs composite films as electrode materials for supercapacitors and capacitive deionization system.2. The electrochemical capacitance of CNTs-CNFs composite films was determined by cyclic voltammetry and impedance spectroscopy. The specific capacitance reaches 143 F/g in 1M aqueous H2SO4.3. The capacitive deionization process of CNTs-CNFs composite films were studied:(1) The CNTs-CNFs composite films are mainly composed of mesopores (2-50nm) and a small portion of macropores (>50nm). The pore size distribution is optimal for CDI application.(2) The optimal grown parameters of CNTs-CNFs composite films for CDI are: the flow rates of acetylene and hydrogen are 3050sccm and 200sccm respectively, the grown temperature is 500-550℃, the grown time is 30-60 minutes. The as-grown CNTs-CNFs composite films show good CDI capacity without any treatments such as plasma etching and annealing.(3) The CDI capacity is dependent on CDI unit cell structure: With the increase of...
Keywords/Search Tags:carbon nanotubes and nanofibres (CNTs-CNFs) composite films, supercapacitor, capacitive deionization (CDI), thermal chemical vapor deposition (CVD)
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