Ultrathin amorphous manganese dioxide nanosheets synthesized with controllable width

We present a one-step synthesis process for ultrathin non-crystalline MnO2 nanosheets. Their thickness is about 2 nm and the width varies from 5 to 20 nm. They induce a higher capacitance than zero-dimensional spheres or one-dimensional rods. When heat treated at elevated temperature MnO2 nanosheets partly grow into crystalline Mn2O3 rods.