The majority of the aforementioned synthetic routes face a
number of disadvantages, such as the use of high temperatures,
complexity, time-consuming, and difficulty to scale-up. To address
these issues, we developed a facile and rapid method to deposit
MnO2 on MWCNTs-OH by chemical reduction of KMnO4 with
MnSO4 in aqueous solution under ambient conditions. Additionally, our synthetic approach can be readily scaled-up. The obtained
MnO2/MWCNTs-OH composite with a MnO2 loading of20 wt% has
a relatively high specific capacitance of 234 F/g at a scan rate of
2 mV/s and exhibits a good cycling stability during 1000 cycles of
charge–discharge. Furthermore, the MnO2/MWCNTs-OH composite exhibits a good ORR activity, which indicates that this composite
has potential applications as a non-noble metal electrocatalyst in
fuel cells and metal–air batteries