Recent advances in Bi2MoO6 based Z-scheme heterojunctions for photocatalytic degradation of pollutants

Since the 70s, many researchers have investigated the photocatalytic degradation of persistent organic pollutants using a variety of semiconductor photocatalysts, especially under visible-light irradiation. The widespread use of metal oxide semiconductors stems from their salient features such as low toxicity, high stability, and resistance to chemical corrosion in aqueous solution. Among these, ternary metal oxides have surpassed binary metal oxides in terms of photocatalytic activity under visible-light irradiation due to their reduced band gaps. This review article focuses on recent progress in the development of bismuth molybdate (Bi2MoO6) based semiconductor heterojunction photocatalysts with a Z-scheme configuration for photocatalytic removal of organic pollutants from water. The two-step excitation strategy, using photocatalysts in a tandem-structured Z-scheme, allows an increase in photo-absorption and, at the same time, maintains a strong thermodynamic driving force for photoreactions to proceed. We firstly introduce a brief description of the persistent organic pollutants problem and the recently acknowledged solutions for their removal by employing heterogeneous photocatalysts, particularly the Bi2MoO6 based Z-scheme photocatalysts. Subsequently, as a base for devising strategies to improve its photocatalytic activity, a broader description of the crystallographic and electronic properties modifications of Bi2MoO6 is revisited. The classification of the different heterojunction types, with special emphasis on Z-scheme configurations, is also presented. We then summarize and discuss the most relevant and recent studies on Bi2MoO6 based Z-scheme heterojunctions photocatalysts and their activity for photodegradation of organic pollutants. Lastly, we present some future perspectives that are considered relevant to the development of advanced and high-efficiency visible light active photocatalysts based on Bi2MoO6.