Intimate Coupling AgI/AgIO₃ Heterojunction Photocatalysts with Excellent Visible-Light-Driven Photocatalytic Activity

Photodegrading toxic organic pollutants in effluents over semiconductor photocatalysts is friendly and promising. The key is to develop a universally powerful and stable photocatalyst. In this work, highly efficient AgIO₃@X heterojunction photocatalysts, composed of AgI and AgIO₃ two phases, are fabricated via a facile in situ reduction method. AgIO₃ is reduced and then AgI is generated on the surface of AgIO₃, so the interfacial interaction between AgI and AgIO₃ is very intimate. Introduction of AgI on the surface of AgIO₃ extends the photoabsorption from an ultraviolet region to a visible region and also greatly improves charge transfer, giving rise to the remarkedly enhanced photocatalysis activity under visible-light excitation over AgIO₃@X samples relative to the pristine AgIO₃. The methyl orange (MO) photodegradation rate constant of the optimal AgIO₃@20% photocatalyst reaches 0.175 min^–1 under visible-light illumination (λ > 420 nm), about 86.5-fold enhanced compared with the pristine counterpart, outperforming most of previously reported state-of-the-art photocatalysts. Particularly, after 20 min of natural sunlight irradiation with a light intensity of 13.8 mW/cm², the AgIO₃@20% sample can rapidly decompose 81.1% of MO. The as-obtained composite photocatalysts also exhibit excellent photocatalytic activity against rhodamine B (RhB) and 2,4-dichlorophenol (2,4-DCP) under the illumination of visible light. The possible reaction pathways and the MO degradation mechanism have been systematically investigated and illustrated. The study paves a new way for designing and developing efficient visible-light-driven photocatalysts with an intimate interfacial interaction.