Aging induced enhancement of pore interconnectivity of porous silica investigated by nitrogen adsorption and cyclic voltammetry

Abstract

Pore interconnectivities of mesoporous silica prepared with precursor sols aged for various times were investigated by N 2 adsorption-desorption measurement and cyclic voltammetry. With increasing aging time of the precursor sol to 4 days, an abnormal decrease in both total open volumes and specific surface areas was found. However, with further increasing the aging time to 15 days, the total open volumes and specific surface areas dramatically increased, indicative of the formation of highly interconnected pores and a remarkable increase in the silica porosity. This was further confirmed by cyclic voltammetry measurements using aqueous potassium iodide solutions on the corresponding silica films, which showed a significant rise in redox current and total charge Q across the films prepared after a longer time aging of precursor sols. This rise can be attributed to the diffusion of I − across the silica films with enhanced pore interconnectivity, despite of the decline in total porosity for some silica samples.