A precursor route to synthesize mesoporous γ-MnO2 microcrystals and their applications in lithium battery and water treatment

MnCO3 microstructures, including 2.3 μm microplates with the thickness of 200 nm and 3.1 μm microspheres stacked with 50 nm-thick sheets, were hydrothermally prepared in the assistance of sodium dodecyl benzene sulphonate (SDBS) and dodecyl sulfonic acid sodium (SDS), respectively. With the as-synthesized MnCO3 as precursors followed by annealing at 400 °C for 4 h, mesoporous γ-MnO2 microplates and microspheres with the pore size of 4–50 nm, which basically preserved the initial shapes, were obtained. The Brunauer–Emmett–Teller surface areas of the as-prepared γ-MnO2 microplates and microspheres were 52.1 m2 g−1 and 50.2 m2 g−1, respectively. The electrochemical property tests over Li+ batteries showed that the initial discharge capacity of γ-MnO2 microplates and microspheres were 1997 mAh g−1 and 1533 mAh g−1. Noticeably, even after 100 cycles, the discharge capacity of γ-MnO2 microplates was still as high as 626 mAh g−1, indicating the decent cycle behavior. In addition, mesoporous γ-MnO2 was also applied as adsorbents in water treatment, and γ-MnO2 microplates and microspheres could remove about 55% and 80% of Congo red.

► Manganese carbonates with different morphologies such as microplates and microspheres were selectively synthesized just by changing the surfactants.
► Mesoporous γ-MnO2 structures were fabricated from themolysis of MnCO3 precursors under inert gas.
► The porous structures exhibited good performances in lithium storage.
► The porous structures were also used as adsorbents in water treatment.