Evolution of Bi Nanowires from BiOBr Nanoplates Through a NaBH_4 Reduction Method with Enhanced Photodegradation Performance

摘要

In this work, we have adopted a coprecipitation method to synthesize BiOBr nanoplates with diameter of 150-450 nm and thickness of 40-80 nm, and then created Bi nanowires (diameter: 6 nm) on their surface through a NaBH4 reduction method. Evolution of Bi nanowires was systematically investigated by varying the concentration of NaBH4 solution and reaction time. It is demonstrated that with increasing the NaBH4 concentration (2 h reaction), Bi nanowires are gradually evolved from BiOBr crystals, and in particular treatment by 110 mM NaBH4 solution leads to the complete evolution of BiOBr nanoplates to Bi nanowires. At a low-concentration NaBH4 solution (30 mM), BiOBr crystals are partially reduced to Bi nanowires with increasing reaction time, and then the Bi nanowires are recrystallized into BiOBr nanowiresanoparticles on the surface of BiOBr nanoplates. At a high-concentration NaBH4 solution (110 mM), BiOBr nanoplates are easily reduced to Bi nanowires with a short reaction time, and further prolonging the reaction time leads to the gradual transformation of Bi nanowires into Bi4O5Br2 nanoparticlesanowires. Photocatalytic performances of the samples were evaluated by eliminating rhodamine B from aqueous solution under simulated sunlight illumination. It is demonstrated that the creation of Bi nanowires (an appropriate content) on the surface of BiOBr nanoplates can produce excellent Bi@BiOBr composite photocatalysts with enhanced photodegradation performances. The underlying enhanced photocatalytic mechanism was investigated and discussed.