Controlled growth of single-crystalline Bi.333(Bi6S9)Br nanorods under hydrothermal conditions for enhanced photocatalytic reduction of Cr (VI)

The rational design of composition and structure of the photocatalytic materials is especially critical for the practical application of photocatalytic technology. Herein, uniform single-crystal Bi.333(Bi6S9)Br nanorods were synthesized for the first time using a one-pot hydrothermal method. By prolonging the hydrothermal reaction time, the evolution process of Bi.333(Bi6S9)Br from nanoparticles to short nanorods, and finally to long nanorods was observed. Bi.333(Bi6S9)Br nanorods can effectively inhibit the recombination of photogenerated electron-hole pairs and effectively adsorb of Cr (VI) due to the presence of surface defects and unique structure, thereby promoting the photocatalytic activity. Bi.333(Bi6S9)Br nanorods exhibited excellent photocatalytic performance as well as promising recyclability in rapidly reducing aqueous Cr (VI) to Cr (III) under visible light. The degradation rate of Cr (VI) reached 90.96% within 60 min, and the structure of Bi.333(Bi6S9)Br did not change after six photocatalytic cycles. The photocatalytic reaction mechanism of nanorods was proposed based on the band structure of Bi.333(Bi6S9)Br and electron spin resonance radical scavenging assay.