Heteropolyacid-Based Heterogeneous Photocatalysts for Environmental Application

Polyoxometalates (POMs) are a wide class of discrete nanosized transition metal–oxygen clusters. The synthesis of POMs has received great interest not only because they present intriguing architectures but also because they have potential applications in catalysis, medicine, electrochemistry, materials design or models for self-assembling nanoscale systems. Recently, POMs have also been studied as green and cheap photocatalysts. The potentialities of POMs are attributed to their unique structural features; indeed, POMs are photostable and non-toxic, have oxygen-rich surfaces and excellent redox properties and possess photochemical characteristics similar to those of the semiconductor photocatalysts. Heteropolyacids (HPAs), including their anions, are a POM subclass. In this chapter their photocatalytic properties when they are immobilized on various supports are described citing a part of the existing literature.