Improving Water Decontamination

Among the many water decontamination methods, photocatalytic degradation is considered as one of the most effective strategies due to its high removal efficiency and environmental friendlessness. However, it is difficult to obtain a high photocatalytic activity under visible-light irradiation with TiO₂ as a catalyst. Therefore, the development of new photocatalysts with visible-light catalytic performance, high surface active sites, and long life of separated electron and hole pairs, has become of interest.

Ag-based semiconductors show excellent visible-light catalytic properties, but they are easily inactivated. AgSCN shows superior stability under irradiation. Itsrelatively large bandgap makes it only ultraviolet light active. The addition of Ag on AgSCN structures can improve the utilization of visible light and can also trap the photogenerated electrons to enhance the catalytic efficiency and stability.

Bo Chen and Xiuling Jiao, Shandong University, Jinan, PR China, and colleagues, have prepared the nanostructured plasmonic photocatalyst silver/silver thiocyanate (Ag@AgSCN). The Ag@AgSCN nanostructures were synthesized by a simple precipitation method using hydrazine hydrate as a reducing agent. This was followed by UV-light-induced reduction, in which the ratio of Ag to AgSCN can be controlled by simply adjusting the photo-induced reduction time. For the Ag@AgSCN nanostructures with an atomic ratio of Ag/AgSCN = 0.0463, the catalytic rate reached to the maximum and the value of Ka was 4.8-fold faster than that of the bare AgSCN.

The degradation of a representative contaminate, oxytetracycline, under visible-light irradiation was used to test the photocatalytic performance of Ag@AgSCN. The Ag@AgSCN nanostructures showed high photocatalytic. The researchers attribute this to the regular morphology, more active sites, and a higher specific surface area. Moreover, the activity toward the degradation after the fifth cycle was almost the same as for the first cycle, which is notable for a Ag-based catalyst.