Well-ordered and nanoporous anodic aluminum oxide (AAO) templates are fabricated through an anodization process by varying cell potentials. The pores of AAO templates are widened by etching in phosphoric acid for different times. Next, carbon nanotubes (CNTs) are directly grown on nanoporous alumina templates by chemical vapor deposition. Subsequently, aluminum is sputtered onto the nanoporous alumina templates with grown CNTs and then aluminum oxide is formed by anodizing. Finally, alumina is

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... nnealed at different temperatures. The longer the widening pore time, the larger the pore diameter and the higher the initial current density of depositing Co. The longer the widening pore time, the higher the capacitance; however, the operation voltage almost remains constant.