Encapsulating Mn3O4 Nanorods in a Shell of SiO2 Nanobubbles for Confined Fenton-Type Catalysis.

Core-shell structured nanomaterials with delicate architectures have attracted considerable attention for realizing multifunctional responses and harnessing multiple interfaces for enhanced functionalities. Here, we report a controllable synthesis of core-shell structured Mn3O4@SiO2NB nanomaterials consisting of Mn3O4 nanorods covered with a shell of SiO2 nanobubbles. A series of Mn3O4@SiO2NB catalysts with tunable secondary structures can be synthesized by simply tuning the feeding ratio and the modification conditions. The as-synthesized Mn3O4@SiO2NB catalysts exhibit excellent catalytic performance in the degradation of methylene blue (MB) because the Fenton-type reaction between Mn3O4 and H2O2 is confined in an MB-rich environment created by the SiO2 nanobubble shell. The confined Fenton-type catalysis maximizes the contact of MB molecules with the reactive oxygen species and significantly promotes the degradation efficiency of MB. Under optimal conditions, Mn3O4@SiO2NB-0.4 can reach a degradation efficiency of 92% at room temperature and neutral pH within 12 min, which outperforms most reported Mn-based catalysts.