One-pot facile synthesis of hierarchical hollow microspheres constructed with MnO2 nanotubes and their application in lithium storage and water treatment

Abstract

Semiconductor α-MnO₂ hierarchical hollow microspheres constructed with nanotubes have been facilely synthesized through a bubble template-based self-scrolling solution route. An energy-minimizing-driven self-assembly of α-MnO₂ nanoparticles on the base of O₂ bubbles is responsible for the formation of hierarchical hollow microsphere structure. The as-obtained α-MnO₂ products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and UV-vis-NIR spectrophotometry. The Li ion storage and water treatment performances of these α-MnO₂ hierarchical hollow microspheres constructed with nanotubes were tested. A discharge capacity as high as 983 mA h g⁻¹ during the 30^th cycle has been delivered at a current density of 300 mA g⁻¹. These as-prepared samples were also used as adsorbents in water treatment, and showed an excellent ability to remove organic pollutants without any other additives.