Structural, optical, and electrical investigation of multilayered MnO2(n)/NiO(p) heterojunctions for supercapacitors applications

•MnO2(n)/NiO(p) heterojunctions were synthesized for supercapacitors applications.•Structural and electrical properties were investigated versus the number of layers.•The specimens formed of 2 and 4 layers constitute good candidates for supercapacitors.•The 2L and 4L electrodes possess a specific capacitance of 3.6×103 and 5.8×103 F.g-1.•The 2L and 4L electrodes possess a specific capacitance retention of 14.8 and 12.9%.