Chapter 4 - The Microwave-Assisted Synthesis of Silica-Based Materials and Their Photocatalysis

Abstract

SiO2 and its based materials, such as zeolites, have been widely used as supporting materials along with metal-oxide semiconductors which offer interesting features including high surface area, accessible reactive sites, stability, etc., for various photocatalytic reactions. In particular, supporting SiO2 with light and active semiconductor metal-oxides namely, TiO2, ZnO, etc., shows excellent UV shielding ability and visible light transparency. Moreover, the light exposing and surface areas of semiconductor metal-oxide photocatalysts also increase with SiO2 support that facilitates higher photocatalytic activity than its bulk without support. Inspired by the advantages of SiO2 supported semiconductor metal-oxides especially in the photocatalysis, various traditional synthetic methods namely, hydrothermal, solution precipitation, impregnation, deposition, coprecipitation, etc., have been reported. However, recently microwave-assisted synthesis of SiO2 based nanomaterials is found to be an effective strategy over the available methods due to the specific roles and advantages of microwave technique including cost-effectiveness, eco-friendly, size controlled synthesis, rapid and uniform supporting for the metal oxides, etc. This chapter mainly describes the importance of microwave in the synthesis of SiO2 based metal oxides for photocatalytic applications.