Carbon nanotubes (CNTs) which are directly grown on nanoporous alumina templates by chemical vapor deposition are modified by radio frequency nitrogen -plasma at different times. Next, alumina is deposited onto the nanoporous alumina templates with grown CNTs by varying deposition times and pH values. Finally, aluminum oxide is annealed. Higher capacitance (2158.3 μF/cm 2 ) and higher operation voltage (57.10 V) are obtained at a better / superior nitrogen-plasma time (20 min) and better chemical liquid phase deposition conditions (time = 3 h and pH = 3.80). Furthermore, the longer the nitrogen-plasma time, the higher the capacitance. The longer the deposition time, the lower the capacitance, but the higher the operation voltage. The higher the deposition pH, the lower the capacitance, however, the higher the operation voltage.Aluminum electrolytic capacitors have been widely used as power supplies for all types of electronic equipment including automobiles, computers, monitors, and other electronic components. The aluminum electrolytic capacitor consists of aluminum anode foil -on which an oxide is prepared by an electrochemical oxidation process -a suitable electrolyte, and aluminum cathode foil. The capacitance of the aluminum cathode foil is much higher than the aluminum anode foil so that the applied voltage appears mainly on the aluminum anode foil, which determines operation voltage and capacitance. 1, 2 Thus, we were concerned principally with the anode electrode. In our previous study, 3 well-ordered nanoporous anodic aluminum oxide (AAO) templates were fabricated through a two-step anodization process by applying voltages of 30-40 V in 0.3 M oxalic acid solution, then carbon nanotubes (CNTs) were grown on nanoporous alumina templates / aluminum foil by chemical vapor deposition (CVD), and next alumina was deposited onto the nanoporous alumina templates with grown CNTs / aluminum foil with grown CNTs. In order to reduce cost, a simply physicochemical method of low-temperature chemical liquid phase deposition was instead of sputtering 4, 5 and alumina was deposited onto the nanoporous alumina templates with grown CNTs in this study.To remove the oxide barrier layer from the pore bottom tips of anodic alumina films, at the end of the second anodization, the previous value of the current density was halved as well as then the sample was re-anodized until reaching stable potential and this process was repeated 8 times until reaching a value close to 0 V. 6 Therefore, for the purpose of the pores being open to the Al layer, the process was applied to this research.In order to improve capacitance and charge density in electric double layer capacitors, carbonaceous materials were modified by RF (radio frequency) nitrogen-plasma surface treatment at 300 W of power, 1.3 Pa of pressure, 150 • C of temperature, and different times (10, 30, and 60 min). 7 So CNTs were modified by RF nitrogen-plasma in this study.Thin aluminum oxide films were deposited on GaN substrates by chemical liquid phase deposition at deposit...
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