An overview on bismuth molybdate based photocatalytic systems: Controlled morphology and enhancement strategies for photocatalytic water purification

Upon varying morphology, structure and composition, bismuth molybdate (BMO) shows different physical and chemical properties. The photocatalytic performance of BMO is strongly influenced by morphology and structure, as they are determinant in tuning its electronic properties. Besides, nanostructured BMO with desired morphology is capable to bestow a great photodegradation performance. Hence, till now, various controlled fabrication routes have been exploited for the production of BMO with desired properties. However, a review explaining the relationship between morphology, structure, route of synthesis, photocatalytic activity, and efficiency of BMO is still missing. To this end, in this review, we firstly summarized various factors, such as pH, temperature, solvent, reaction time and surfactants, which help in controlled synthesis of BMO, and then, dealt with explanation of how change in conditions leads to change in morphology. Afterwards, the synthesis, morphology and photocatalytic performance of BMO with different dimensions are discussed. Due to some drawbacks of pristine BMO such as alignment of band gap and charge carrier's recombination, some modifications to BMO such as doping, heterojunction, homojunction, Z-scheme formation, etc. have been explored. In addition, the environmental applications of modified BMO, along with photocatalytic mechanism involved and efficiency extend, are elucidated. Similarly, degradation of various pollutants and deactivation of some organisms like Hela cancer cells and bacteria are also brought under discussion. Finally, potential applications and unanswered challenges about BMO are propounded for future research.