Developing a general method for encapsulation of metal oxide nanoparticles in mesoporous silica shell by unraveling its formation mechanism

Abstract

Abstract Our previous work reports synthesis of a highly stable watermelon-like CuO NPs@mSiO2 core-shell material (CuO nanoparticles embedded in mesoporous silica) by a modified Stober method. Here, its formation mechanism is unraveled by investigating the effects of synthesis parameters, i.e. polyvinylpyrrolidone (PVP) and cetyltrimethyl ammonium bromide (CTAB) concentrations, copper nitrate and tetraethyl orthosilicate (TEOS) amounts, as well as alkali types and amounts, on the solid product structure and particle morphology for the purpose of developing a general method for synthesis of single and composite metal oxide NPs@mSiO2. With such a method, various types of metal oxide NPs@mSiO2 have been synthesized. It is shown that the structure and particle morphology of these core-shell materials are not only related to the synthesis parameters, but also dependent on the types of metal oxides. More interestingly, these core-shell materials are potential for facilely fabricating bifunctional catalysts by further modifying mSiO2 shell or coating another type of catalyst such as zeolites.