Facile synthesis and electrochemical properties of MnO2/carbon nanotubes

Abstract The poor electrical conductivity of MnO 2 limits its use as an electrode material. To overcome this limitation, we report an easy and rapid approach to deposit nanosized MnO 2 onto multi-wall carbon nanotubes functionalized with hydroxyl groups (MWCNTs-OH) by chemical reduction of KMnO 4 with MnSO 4 in aqueous solution under ambient conditions. Characterization with XRD and TEM reveals that the obtained MnO 2 /MWCNTs-OH composite is nanocrystalline and partially covered by MnO 2 nanosheets with a thickness of 1–3 nm at a MnO 2 loading of 20 wt%. Cyclic voltammetry (CV) and galvanostatic charge–discharge measurements reveal that the MnO 2 /MWCNTs-OH composite with a MnO 2 loading of 20 wt% has a relatively high specific capacitance of 234 F/g at a scan rate of 2 mV/s and exhibits good cycling stability. Furthermore, the oxygen reduction reaction (ORR) shows that MnO 2 /MWCNTs-OH composite may have potential applications as a non-noble metal electrocatalyst in fuel cells and metal–air batteries.