A waxberry-like SiO2@MnSiO3 core-shell nanocomposite synthesized via a simple solvothermal self-template method and its potential in catalytic degradation and heavy metal ion removal

摘要

A novel waxberry-like SiO2@ MnSiO3 core-shell nanocomposite was facilely fabricated via the simple one-step thermal treatment of SiO2 nanospheres, MnCl2 center dot 4H(2)O, ethylenediamine (EDA), and ethylene glycol (EG). Through an intensive investigation of the effects of Si/Mn molar ratio and reaction time on the grain growth characteristics, a self-template growth mechanism of SiO2@MnSiO3 was proposed. The self-template silica nanospheres released silicate anions slowly from their surfaces by alkali etching in the presence of EDA, and a fast precipitation reaction between Mn2+ cations and silicate anions occurred within the interfacial regions, eventually leading to the formation of a MnSiO3 shell on the surfaces of silica nanospheres. A well-defined waxberry-like SiO2@ MnSiO3 nanostructure was obtained with a Si/Mn molar ratio of 5 : 1 and a reaction time of 10 h according to our experiments. Interestingly, this SiO2@MnSiO3 exhibited a high catalytic activity for oxidative degradation of methylene blue (MB); more than 93% of MB could be decomposed within 40 min. Moreover, it could also act as a potential adsorbent for efficient removal of Pb2+ ions from aqueous solution. The Pb2+ adsorption capacity was up to 50.5 mg g(-1), which was significantly higher than those found for many other conventional adsorbents. Overall, this work not only provides a new insight into the fabrication of silica-supported MnSiO3 nanocomposites but also demonstrates their excellent performance in heterogeneous catalysis and adsorption.