Facile synthesis of monodispersed mesoporous silica nanoparticles with ultra-large mesopores through a NaBH4-assisted hydrothermal process

Abstract

This work reports the facile synthesis of monodispersed ultra-large mesopore mesoporous silica nanoparticles (ULP-MSNs) through a new and simple NaBH4-assisted hydrothermal process (NAH process). Such preparation of ULP-MSNs enables the small mesopore size (<3 nm) of as-prepared conventional MSNs to be effectively enlarged to over 20 nm. The synthetic parameters were systematically studied, and it was shown that the initial ethanol added in the synthesis mixture (1st ethanol), NaBH4, HCl(a.q.) and the ethanol added in the mixture (2nd ethanol) during the hydrothermal (HT) process and HT conditions play synergistic roles in enlarging mesopores by NAH process. We also revealed the mesopore-enlargement mechanism. By this method, the resultant ULP-MSNs possess tunable ultra-large mesopore sizes (18–31 nm), monodispersed spherical morphology, and controllable particle sizes (105–268 nm). The method presented here could effectively enlarge and adjust the mesopores of the MSNs. We supposed our approach may provide a platform of nanotechnology for the preparation of porous silica materials with adjustable mesopore sizes, which will be promising for practical applications.