Ionic liquid-assisted hydrothermal synthesis of β-MnO2 with hollow polyhedra morphology

β-MnO2 with hollow polyhedra morphology has been successfully synthesized via an ionic liquid-assisted hydrothermal synthetic method, and the effect of the ionic liquid N-butylpyridinium tetrafluoroborate on the formation of β-MnO2 with hollow polyhedra morphology has been investigated on the basis of the hydrothermal treatment temperature, the concentration of the ionic liquid, and the concentration of HCl. A formation process of β-MnO2 with hollow polyhedra morphology is given. The ionic liquid acts as a soft template in the formation of β-MnO2 with hollow polyhedra morphology, which decreases the particle surface energy and controls the growth direction of β-MnO2 polyhedra.