Twin engineering of photocatalysts: a minireview
Twin crystals with highly ordered atomic arrangement can not only promote the transport of free charge carriers (electrons and holes) inside a single crystalline photocatalyst, but also limit the recombination of photoexcited charge carriers owing to their self-building electrostatic field. Hence, the investigations on twin-dependent photocatalytic performances of crystalline micro-/nanostructures have received much attention in recent years. However, there is still no specialized review article on twin engineering of photocatalysts so far. Herein, the existing twinned micro-/nanostructures, mainly including metal sulfides and metal oxides, are overviewed on the basis of the synthesis engineering, transmission electron microscopy (TEM) characterization and twin-dependent photocatalytic mechanism. Some challenging issues and future directions are also discussed. Expectantly, this minireview would serve as a theoretical guidance for people who are now focusing on twin crystals to design and synthesize novel photocatalysts.