Recent advances in nano-semiconductors photocatalysis for degrading organic contaminants and microbial disinfection in wastewater: A comprehensive review

Recently, many reviews have discussed the applications of semiconductor photocatalysts to environmental issues. These publications mainly deal with the morphology, design, and synthesis of semiconductors. But the new studies on semiconductor photocatalysis still need to be reviewed. The present review focuses on the major aspects that have received little attention in the previous studies. It provides valuable information on organic and microbial pollutants, as well as the advantages and drawbacks of conventional physical, chemical, and biological technologies that are used for their elimination. The operating parameters, such as photocatalyst dose, initial concentration, pH solution, light intensity , dissolved oxygen, addition of H 2 O 2 , direct photolysis, and reaction temperature were briefly explained. This critical review summarizes the modifications of semiconductors using different approaches such as surface engineering, doping, sensitizing, and coupling. Furthermore, supported and core/shell heterogeneous nanoparticles are explained in details. Common heterogeneous photocatalysts like TiO 2 -based photocatalysts, silver-based photocatalysts, and graphitic carbon nitride-based (g-C 3 N 4 ), are discussed in the current review. The photocatalytic mechanism of heterojunction photocatalysts such as p-n heterojunctions, type I, type II, and Z-scheme heterojunction was also described.