Hierarchical mesoporous MoO2 hollow microspheres: Synthesis, mechanism and application in removing Cr (VI) from wastewater

Abstract Hierarchical MoO 2 hollow microspheres have been successfully fabricated on a large scale through a convenient hydrothermal reductive process. MoO 2 hollow microspheres are composed of subunits (nanospheres or nanoplates), which are actually self-aggregated by hundreds of tiny primary nanoparticles. BET nitrogen adsorption reveals that the MoO 2 hollow microspheres have mesoporous shell with pore size of 5–20 nm. Reaction parameters, such as mole ratio of reactant, reaction temperature and time, were discussed in detail. Center-hollowing evolution process induced by Ostwald ripening was proposed to explain the formation mechanism of hierarchical MoO 2 hollow microspheres. The adsorption ability of MoO 2 hollow microspheres was evaluated by adsorbing Cr (VI) at room temperature. The experimental results indicated that MoO 2 absorbent displayed higher adsorption capacity compared to activated carbon, which would be potential application in wastewater treatment.