Photocatalytic Efficiency of Bi-Based Aurivillius Compounds: Critical Review and Discernment of the Factors Involved

The rapid development of industries to gain technical advancement is packed with environmental-related issues. This is a primary and major concern all over the world. Photocatalysis has proven to be a potential approach to address the issues of environmental problems. Semiconductor material-based photocatalysis is the forefront and viable method to achieve the same. Among metal oxide/selenide/sulfide/phosphide/halide/oxyhalide materials, Bi-based Aurivillius compounds have been widely studied in recent years, because of their excellent physical and chemical properties. These compounds are found to be narrow bandgap materials, which are nontoxic, noncorrosive, and relatively low cost. The ability of Aurivillius compounds to form 2D morphologies is a major advantage in the development of high surface area nano-photocatalysts, which in turn increases catalyst efficiency by providing more active sites for effluent degradation. The bandgap can be tuned either by employing strategies like the formation of nanocomposites with RGO or by the creation of heterostructures with Bi-based Aurivillius compounds. This approach has attracted researchers for visible light-driven photocatalytic applications. This chapter focuses on basic properties and crystal structure of the Bi-based Aurivillius compounds, such as Bi2MO6 (M = Cr, Mo, W), Bi4Ti3O12, and (BiO)2CO3. Simple and most studied synthesis techniques, such as hydro−/solvothermal, sol–gel, and coprecipitation methods, are discussed. The photocatalytic mechanism of various hazardous pollutants and its degradation are explained along with the advantages and disadvantages of Bi-based Aurivillius compounds. The dependence of morphology control and surface modification of Bi-based Aurivillius compounds for photocatalytic applications are explored in detail based on the recent studies. Applications of these Bi-based Aurivillius compounds such as dye degradation, non-dye-based organic compounds, pharmaceutical waste degradation, heavy metal reduction, and bacterial disinfection are covered. This chapter mainly focuses on the emerging Z-scheme-based photocatalysis mechanism in detail in order to mitigate the common problem of small bandgap materials, such as chage recombination. Recent progress in the Z-scheme-based heterostructures is elaborated for enhanced photocatalytic degradation of dyes, non-dye-based compounds, and pharmaceutical wastes. The photocatalytic reduction of heavy metals by Bi-based Aurivillius compounds is presented. Attention is given for the most dangerous heavy metal Cr (VI) reduction process. The reaction scheme involved in the reduction of toxic Cr (VI) to nontoxic Cr (III) is described. Finally, based on the previous studies, bacterial disinfection by Bi-based Aurivillius materials is presented with the mechanism.