Yan Zhenhua,Wang Min,Lu Youqin,Liu Renmin,Zhao Jinsheng
Three carbon-supported Pt–Co alloys with varying Pt to Co atom ratio (Pt 2 –Co/C, Pt–Co/C, Pt–Co 2 /C) were prepared by NaBH 4 reduction in ethylene glycol at room temperature. As supported by X-ray diffraction, all the prepared Pt–Co nanoparticles have a single-phase face-centered cubic structure. Transmission electron microscopy indicates that all nanoparticles have small particle-size range and are highly dispersed on carbon support. Catalytic properties of the synthesized Pt–Co alloy catalysts were analyzed using cyclic voltammetry and linear sweep voltammetry methods, and the results suggested that Pt–Co/C catalysts exhibit the best Pt mass activity and the highest stability for the oxygen reduction reaction (ORR) when compared with Pt/C catalyst and other Pt–Co alloy catalyst in both acidic and neutral media. Kinetic analysis reveals that the ORR on Pt–Co alloy follows the four-electron pathway leading to water. As the cathode catalyst, the single-chamber microbial fuel cell tests indicated the much better performance of Pt–Co alloy than that of commercial Pt/C.
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 nanowires/nanoparticles 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 nanoparticles/nanowires. 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.
危险品化学品经营许可证（带存储）