Pore size controlled synthesis of SiO2 colloidal crystal

Abstract

In this work, lysine has been used to catalyze the hydrolysis of tetraethyl orthosilicate in order to fabricate uniform-sized silica nanospheres(SNSs). First, SNSs seeds were synthesized. Then the sphere sizes of silica nanoparticles were expanded by a seed regrowth method. Finally, by evaporating the solvent in the SNSs dispersion, SNSs of different sizes self-assembled into silica colloidal crystals of pore sizes ranging from 5 to 9 nm as characterized by N2 physisorption. From SEM images of the different silica colloidal crystals, it can be seen that the sizes of SNSs were delicately expanded from 26 to 50 nm. TEM images confirmed that the SNSs were periodically stacked within the silica colloidal crystals. By a group of controlled experiments, it is found that the key for the quality control of the SNSs and hence for the formation of a fine colloidal crystal is the additional supplement of lysine during the silica seed regrowth process. The function mechanism of lysine in the process was also proposed.