Synthesis Of Mono-/Multi-layer Hollow Materials Based On Hydrothermal Carbon

In recent years hollow micro-and nano-structured spheres,especially those with complex shell structures,have drawn significant attention due to their unique properties such as well-defined morphology,low density,high surface-to-volume ratio and excellent chemical and thermal stabilities.Their attractive properties have stimulated tremendous research interest because of their fascinating potential in drug delivery,nanoscale reactors,superamphiphobic surfaces,catalysis and energy storage,and considerable efforts have been devoted to exploring various strategies to generate hollow structures possessing optimized physical and chemical properties for specific applications.Thus,many types of hollow spheres have been fabricated through various synthesis routes.In this work,C@SiO₂@F coating and h-SiO₂@F coating were prepared by using hydrothermal carbon spheres as template material,and the superamphiphobicity properties of coatings was explored;meanwhile,yolk-shell MgO spheres and multiple-shell MgO/Pt spheres were prepared on the basis of the hydrothermal carbon,then its electrocatalytic properties were investigated.Finally,the formation mechanism of multiple-shell MgO/Pt hollow spheres was explored.the main contents are as follows:?1?In this work,by using stringed carbon spheres as template material,a series of hierarchical 3D cross-linked SiO₂ coated carbon spheres and hollow SiO₂ spheres were fabricated,and spray-coated on glass slides,followed by the fluorination treatment with perfluorotrichlorosilane.The surface characterization and surface wettability data indicated that hollow SiO₂ spheres spray-coated surfaces showed better superhydrophobicity and superoleophobcity properties than the corresponding solid C@SiO₂ coated surface.This study further demonstrated that superamphiphobicity depends on two critical factors,namely a cavity-and spot-rich hierarchical structure and sufficient air cushion in the cavity.Moreover,the optimal conditions for the preparation of hollow Si_O2 coated glass slide were identified after a systematic investigation of various concentrations of the carbon precursor and TEOS.It was found that when 0.10 g carbon spheres prepared from 1.0 M carbon precursor were used as the template and 20 mg mL^-1 TEOS was used as silica precursor,the hollow SiO₂ coated glass slide exhibited the best superamphiphobic performance.?2?In this paper,we present a template-free strategy for the fabrication of yolk-shell MgO spheres and multiple-shell MgO/Pt spheres.By using a simplified two-step process,spherical C-MgCO₃ or Pt-C-MgCO₃ composites were first prepared by hydrothermal treatment and then transformed into yolk-shell MgO spheres and multiple-shell MgO/Pt spheres by combustion in air at 500°C.The structure of multi-shell hollow spheres was characterizedand confirmed by TEM,SEM,HRTEM,XPS,HAADF-SEM,and nitrogen adsorption-desorption.The results reveal that MgO/Pt MSHSs have a highly porous and self-supporting structure with a high surface area of 16.7 m² g^-1 and possesses a high surface area and sufficient adsorption sites.Since Pt nanocrystals are monodispersedly loaded onto multiple-shell structures,the composites could provide more catalytically active sites for electrocatalytic reactions than commercially available Pt electrocatalysts.Moreover,our research indicates that the as-prepared multiple-shell MgO/Pt hollow spheres exhibit enhanced electrocatalytic activity and long-term stability towards the oxidation reaction of methanol.?3?Through a series of controlled experiments,the effects of glucose,MgCO₃·3H₂O and Pt precursors on the formation of MgO/Pt multiple-shell hollow spheres were investigated respectively.Based on the experimental results,the formation mechanism of MgO/Pt multiple-shell hollow spheres was analyzed,and proposed a relatively reliable formation mechanism model.