Low-temperature and template-free fabrication of cobalt oxide acicular nanotube arrays and their applications in supercapacitorsElectronic supplementary information (ESI) available: Experimental details, charge-discharge curves, and details about the estimation of film mass. See DOI: 10.1039/c4ta06811d

• Main Authors: Kung, Chung-Wei, Cheng, Yu-Heng, Tseng, Chuan-Ming, Chou, Li-Yao, Ho, Kuo-Chuan
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c4ta06811d

Layered cobalt carbonate hydroxide (LCCH) acicular nanorod arrays (ANRAs) grown on a graphite substrate are converted to Co 3 O 4 acicular nanotube arrays (ANTAs) via the anion-exchange reaction and Kirkendall effect at low temperature. The Co 3 O 4 ANTAs exhibit an area capacitance of 369 mF cm −2 and a specific capacitance of 979 F g −1 at 2.5 mA cm −2 , which are much higher than those of the Co 3 O 4 ANRAs prepared by calcining the LCCH ANRAs at 350 °C (64.5 mF cm −2 and 191 F g −1 ). Layered cobalt carbonate hydroxide (LCCH) acicular nanorod arrays (ANRAs) are converted to Co 3 O 4 acicular nanotube arrays (ANTAs) via Kirkendall effect. The Co 3 O 4 ANTAs exhibit a specific capacitance of 979 F g −1 , which is higher than that of the Co 3 O 4 ANRAs (191 F g −1 ).