The effect of acid concentration and the related mechanism of the formation of the products are investigated. We demonstrate that the intermediate of MnO2 plays a key role in forming the hollow

structures of PANI. The capacitance of the composite achieves 207 F g−1, and the results suggest that the MnO2/PANI composites show superior performance over pure PANI or MnO2. Acknowledgements This work was supported by the National Basic Research Program of China (2012CB932800) and the National Science Foundation of China (51171092, 20906045, 90923011). Trichostatin A The authors also thank the Shandong University for their financial support (nos.31370056431211, 31370070614018, and 31370056431211). Electronic supplementary material Additional Lumacaftor molecular weight file 1: Figure S1: FTIR spectra of MnO2/PANI fabricated in 0.1 M NaOH, 0 HClO4, 0.02 M. Figure S2. FTIR spectra of polyaniline (curve a) and the composites after heat treatment (curves b to f): MnO2/PANI fabricated in 0.1 M NaOH, and 0, 0.02, 0.05, and 0.1 M HClO4. Figure S3. CV curves of the composites before and after 100 cycles stability tests in 0.1 M HClO4 solution at 50 mV s−1,

(A-D) samples fabricated in 1, 0.05, and 0.02 M HClO4, and 0.1 M NaOH and (E) MnO2 obtained by heating MnO2/PANI composite fabricated in 0.02 M HClO4. (DOC 744 KB) References 1. Wang K, Huang J, Wei Z: Conducting polyaniline nanowire arrays for high performance supercapacitors. J Phys Chem C 2010, 114:8062–8067.CrossRef 2. Zhang K, Zhang LL, Zhao XS, Wu J: Graphene/polyaniline nanofiber composites as supercapacitor electrodes. Chem Mater 2010, 22:1392–1401.CrossRef 3. Huang J, Virji S, Weiller BH, Kaner RB: Polyaniline nanofibers: facile synthesis and chemical sensors. J Am Chem Soc 2003, 125:314–315.CrossRef 4. McQuade

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