Direct Reduction of Graphene Oxide by Ni Foam as a High-Capacitance Supercapacitor Electrode

• Published in: ACS applied materials & interfaces 2016-01, Vol.8 (3), p.2297-2305
• Main Authors: Yang, Jing, Zhang, Enwei, Li, Xiaofeng, Yu, Yunhua, Qu, Jin, Yu, Zhong-Zhen
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.5b11337

Three dimensional reduced graphene oxide (RGO)/Ni foam composites are prepared by a facile approach without using harmful reducing agents. Graphene oxide is reduced by Ni foam directly in its aqueous suspension at pH 2 at room temperature, and the resultant RGO sheets simultaneously assemble around the pillars of the Ni foam. The RGO/Ni foam composite is used as a binder-free supercapacitor electrode and exhibits high electrochemical properties. Its areal capacitance is easily tuned by varying the reduction time for different RGO loadings. When the reduction time increases from 3 to 15 days, the areal capacitance of the composite increases from 26.0 to 136.8 mF cm–2 at 0.5 mA cm–2. Temperature is proven to be a key factor in influencing the reduction efficiency. The composite prepared by 5 h reduction at 70 °C exhibits even better electrochemical properties than its counterpart prepared by 15 day reduction at ambient temperature. The 5 h RGO/Ni foam composite shows an areal capacitance of 206.7 mF cm–2 at 0.5 mA cm–2 and good rate performance and cycling stability with areal capacitance retention of 97.4% after 10000 cycles at 3 mA cm–2. Further extending the reduction time to 9 h at 70 °C, the composite shows a high areal capacitance of 323 mF cm–2 at 0.5 mA cm–2. Moreover, the good rate performance and cycling stability are still maintained.