Fabrication, characterization and catalytic activity of α-MnO2 nanowires for dye degradation of reactive black 5

•α-MnO2 nanowires (NWs) grown using hydrothermal method.•The dislocation density and band gap decreases with oxidizer molarity.•Catalytic activity correlated to crystallite size, dislocation density and Eg.•α-MnO2 NWs application to RB5 dye degradation with Fenton like mechanism.

α-MnO2 nanowires (NWs) prepared by hydrothermal method are characterized using XRD and FT-IR. The crystallite size, surface area of NWs increases, whereas dislocation density and band gap decreases with an increase in oxidizer molarity. The band gap decreases from 2.55 to 1.27 eV. The above observations correlate well with the enhanced catalytic activity of MnO2 NWs for degradation of azo dye reactive black 5 (RB5). About 70% of the dye were successfully removed in 60 min using 20 mg of MnO2 NWs in the presence of 6 mL of H2O2. MnO2 NWs show a good reusability, suggesting it as an effective and recyclable catalyst.