One-step hydrothermal synthesis of the Ag/AgI heterojunction with highly enhanced visible-light photocatalytic performances

The Ag/AgI heterojunction was prepared by a facile, one-step and low-temperature hydrothermal synthesis method with P, I₂ and Ag₂O. The approach proves a green and simple route to the products, which avoided multiple-step synthesis and the subsequent time-consuming photoreduction. The samples were carefully characterised by X-ray diffraction, X-ray photoelectronic spectra, scanning electron microscopy, transmission electron micrographs and ultraviolet-visible-light techniques. The results show that Ag nanoparticles were uniformly distributed on the surface of AgI and the heterostructure was formed. Under visible light, the photocatalytic activity of the Ag/AgI composites for the degradation of rhodamine B (RhB) was efficient and much higher than that of pure AgI. In particular, the Ag/AgI composites (at 120°C for 4 h) exhibited the best photocatalytic activity, and nearly 98% of RhB was degraded within 20 min. Remarkably, the photocatalytic degradation followed the pseudo-first-order reaction model and the corresponding apparent first-order rate constant of 0.157 min^-1 which is five times more than that of pure AgI. The enhanced photocatalytic activity of Ag/AgI can be attributed to the strong surface plasmon resonances.