Polymer template assisted construction of spherical Co3O4@meso-SiO2 yolk-shell nanoreactors for catalytic combustion of volatile organic compounds

Co3O4@SiO2 yolk-shell materials containing Co3O4 nanoparticles protected against aggregation and easily accessible for gaseous reactants inside a mesoporous SiO2 shell were developed for the catalytic combustion of volatile organic compounds (VOCs). Spherical polymer templates with an appropriate cation adsorption capacity were used as scaffolding for the construction of these structures by the bottom-up strategy. An application of polystyrene led to accumulation of introduced cobalt phase within the SiO2 layer and favored the formation of catalytically inactive Co silicate species. On the other hand, poly(maleic anhydride-co-divinylbenzene) modified with diethylenetriamine gave improved penetration of the composite interior by Co2+ cations and highly dispersed Co3O4 nanoparticles after calcination. The latter materials appeared excellent nanoreactors for the catalytic combustion of toluene. The real role of the active phase was determined by characterization of the developed catalysts with XRD, N2 adsorption, SEM-EDS, TEM, UV-Vis-DR, FT-IR, H2-TPR, isothermal oxidation-reduction analyses, XPS, XAS and electrochemical measurements.