One-step synthesis of Bi(Bi2S3)/BiOCl heterojunctions by a simple solid state milling method and their visible light photoreactivity

Bi or Bi2S3 are commonly used to improve the photocatalytic performance of bismuth-based photocatalysts because of surface plasmon resonance (SPR) effect or visible light absorption efficiency. Nevertheless, the modified efficiency between Bi and Bi2S3 has never been compared. In addition, Bi and Bi2S3 modified semiconductors were usually prepared via two-step routes, where a semiconductor was firstly prepared and then reduced by a reducing reagent like NaBH4 or ethylene glycol and sulfurized by thiourea (TU), Na2S or thioacetamide (TAA). Herein, a facile one-step solid state reaction route was used to prepare Bi(Bi2S3)/BiOCl photocatalysts at room temperature through the reaction between Bi(NO3)3·5H2O and KCl followed by sulfur sources. More importantly, these sulfur sources not only acted as sulfurization reagents, but also showed reducibility to different extent. TU possessed the strongest reducibility, whereas Na2S presented the strongest sulfurization ability. The investigation on the photocatalytic activity of these composites for rhodamine B (RhB) and malachite green (MG) degradation under visible light irradiation shows that Bi-coupled BiOCl exhibits the highest degradation efficiency, which further demonstrates important role of SPR effect of Bi.