We developed for the first time an in situ co-crystallization route for fabrication of a heterojunctional photocatalyst g-C₃N₄/Bi₅O₇I by adopting melamine and BiOI as coprecursors. This synthetic method enables intimate interfacial interaction with chemical bonding between g-C₃N₄ and Bi₅O₇I, which is beneficial for charge transfer at the interface. The photocatalysis properties of g-C₃N₄/Bi₅O₇I composites were studied by photodegradation of Rhodamine B (RhB) and phenol and generation of transient photocurrent with illumination of visible-light (λ > 420 nm), The results revealed that the g-C₃N₄/Bi₅O₇I composite shows enhanced photocatalytic reactivity compared to the pristine g-C₃N₄ and Bi₅O₇I samples. Investigations on the behaviors of charge carriers via electrochemical impedance spectra (EIS) and photoluminescence (PL) spectra suggests that the g-C₃N₄/Bi₅O₇I heterojunctional structure constructed of the in situ co-thermolysis approach is responsible for the efficient separation and transfer of photogenerated electrons (e^–) and holes (h⁺), thus giving rise to the higher photocatalytic activity. The present work opens a new avenue for manipulation of high-performance semiconductor heterojunction for photocatalytic and photoelectrochemical application. 

J. Phys. Chem. C, 2015