In recent years, supercapacitors have attracted a lot of attention due to their applications in portable electronic devices such as mobile phones, laptops, digital camera and also for power applications in hybrid electric vehicles, engine start, and solar energy storage, etc. [1-3]. Transition metal oxides and carbon materials are widely being used in supercapacitors. Among transition metal oxides, MnO₂ has been one of the most studied electrode materials because of its cost effectiveness, natural abundance and environmental compatibility. In spite of its various advantages, MnO₂ in its pure state is not very useful for supercapacitor applications because of its poor electrical conductivity and electrochemical dissolution upon cycling. On the other hand, graphene has drawn considerable interest because of its ultrahigh surface area (up to 2630 m²/g), and excellent conductivity. Up to now, composites of graphene and MnO₂ have been used to improve their capacitance.

We have synthesized hetero-structured - nanorods using the low temperature hydrothermal technique [4]. Finally -/graphene nanocomposite was synthesized by sonochemical co-precipitation method as reported earlier [5]. Graphene oxide power, suspended in sulfuric acid solution (1mg/ml), and manganese sulfate (dissolved in sulfuric acid) were mixed together and potassium permanganate solution was added to this solution drop by drop. After 2 hours -/graphene nanocomposite was filtered using centrifuge, washed with DI water and ethanol and dried. The phase structure of - nanorods and -/graphene nanocomposites were studied using powder X-ray diffraction (XRD). The results of physical, thermal and electrochemical characterization of -/graphene nanocomposite will be presented during 231^st Electrochemical Society Meeting.

References:

1. Z. Yang, J. Zhang, M.C. Kintner-Meyer, X. Lu, D. Choi, J.P. Lemmon, J. Liu, Chem. Rev. 111 (2011) 3577.
2. H. Zhang, G. Cao, Y. Yang, Energ. Environ. Sci. 2 (2009) 932.
3. X.H. Lu, X. Huang, S.L. Xie, T. Zhai, C.S. Wang, P. Zhang, M.H. Yu, W. Li, C.L. Liang, Y.X. Tong, J. Mater. Chem. 22 (2012) 13357.
4.  Z.K. Ghouri, M.S. Akhtar, A. Zahoor, N. A. M. Barakat, W. Han, M. Park, B. Pant, P.S. Saud, C. H. Lee, H. Y. Kim, J. Alloy and Compounds 642 (2015) 210 .
5. B. Zhao, M. Lu, Z. Wang, Z. Jiao, P. Hu, Q. Gao, Y. Jiang, L. Cheng, J. Alloy and Compounds B 663 (2016) 180.