“…Consequently, it is very important and indispensable to develop rechargeable batteries and supercapacitors materials for energy storage [1][2][3][4]. Transition metal oxide (such as MnO 2 [5,6], Co 3 O 4 [7,8], NiO [9,10]) have been extensively studied for rechargeable batteries and supercapacitors applications owing to their good structural stability and excellent charge storage characteristics [2,11,12]. Compared to other transition metal oxides, MnO 2 is generally regarded as the most promising one for the electrode material of batteries and supercapacitors because of its good cycle stability, cost effectiveness, high surface area, ideal charge storage characteristics and environmental friendliness [6,[13][14][15][16][17].…”