Improving the performance of graphite anode in a Microbial Fuel Cell via PANI encapsulated α-MnO2 composite modification for efficient power generation and methyl red removal

•Encapsulation of α-MnO2 NPs by conducting PANI using in situ polymerizations.•Modification of PGE by α-MnO2/PANI composite using drop-cast method.•Maximum power generation of 820.02 ± 7.86 mW m−2 by α-MnO2/PANI/PGE.•High decolorization efficiency of 95.57 ± 2.26% by α-MnO2/PANI/PGE.•Achieving maximum COD removal of 74.59 ± 1.57% using α-MnO2/PANI/PGE.