Application of Bismuth-Based Photocatalysts in Environmental Protection

Abstract

Photocatalysis by use of advanced oxidation processes (AOPs) is gaining attention as an effective method of air purification and water treatment. Undoubtedly, photocatalysis can also be applied to produce useful fuels from photocatalytic reduction of CO2 and splitting of water, or it can be utilized as a ``green{''} technology in industrial production. Despite recent research into other photocatalysts (e.g., TiO2 and perovskites), bismuth-based semiconductors such as Bi2O3, BiPO4, (BiO)(2)CO3, BiOX (where X = Cl, Br, and I), and pentavalent bismuthates (e.g., NaBiO3) are most promising because of their low cost, nontoxicity, and high oxidizing and reduction abilities in solar and visible light. Moreover, the conduction band edge and the valence band edge of Bi-based photocatalysts can be designed by using a suitable strategy for preparation of these materials. The photocatalytic activity of Bi-based materials can be additionally enhanced by heterostructures, e.g., using carbon or graphene quantum dots, Ag/AgCl, modified TiO2, or Fe3O4. This chapter aims to highlight recent advancements in application of Bi-based photocatalysts and heterostructures in environmental protection. Albeit nonexhaustive, this review explores the progress made in the last 6 years by focusing on solar and visible light-driven degradation processes to eliminate such contaminants as antibiotics, nonsteroidal anti-inflammatory drugs, beta blockers, anticonvulsants, hormones, resorcinol, bisphenol A, and other derivatives of phenol, many of which have been detected in aqueous ecosystems. The application of Bi-based photocatalysts for removing NOx from indoor air using solar and visible light illumination is also presented. Finally, advances in water splitting and CO2 reduction to CO and CH4 with Bi-based photocatalysts are discussed.