Synthesis of three-dimensional flower-like cobalt sulfide hierarchical architectures for supercapacitors
| Autor: | Chun-Ming Chiu, 邱俊銘 |
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| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 In recent years, metal sulfides with various morphologies have attracted much attention due to their outstanding physical and chemical properties. In this study, a facile and rapid method is used to prepare three-dimensional (3D) flower-like Co9S8 hierarchitectures. The factors to influence the morphology and the corresponding supercapacitor (SC) performance are investigated, including the reaction temperature and time for dodecanethiol, as well as the annealing temperature and the atmosphere for synthesizing cobalt sulfide nanostructures. Based on scanning electron microscope (SEM) and transmission electron microscope (TEM) observations, a self-assembly process is proposed to explain the formation of the 3D flower-like Co9S8 hierarchitectures. In addition, the pseudocapacitive properties of the Co9S8 nanoflower SC electrode are evaluated by cyclic voltammetry and galvanostatic charge-discharge tests in a 6 M KOH electrolyte. It was found that the maximum specific capacitance(CF) of 1010 F g-1 can be achieved when 12.5 mg 3D flower-like cobalt sulfide was loaded on the flexible Ni foam (1 cm2) as the SC electrode. This outstanding electrochemistry performance can be attributed to the high specific surface area and high conductivity benefited from the two-dimensional (2D) flower petals and the carbon layer, respectively. Furthermore, this SC electrode also shows good electrochemical reversibility since its charge-discharge curves present nearly symmetrical shapes and the CF still remains 534 F g-1 after 700 charge-discharge cycles test. The results demonstrate that the Co9S8 nanoflower is quite promising to be considered as a highly efficient active material for SCs. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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