Figure 1

SEM images of MnO 2 samples obtained under (a) neutral and (b) acidic conditions. The scale bar is 1 μm. The inset shows the enlarged SEM image of MnO2 sample and the scale bar is 200 nm.
SEM images of MnO 2 samples obtained under (a) neutral and (b) acidic conditions. The scale bar is 1 μm. The inset shows the enlarged SEM image of MnO2 sample and the scale bar is 200 nm.