修饰AuAg合金纳米颗粒对BiOBr纳米片光催化降解和还原性能的提高

Enhanced Photocatalytic Degradation and Reduction Activity of BiOBr Nanoplates by the Decoration of AuAg Alloy Nanoparticles

采用水热法制备出BiOBr纳米片,并通过光还原法将Au、Ag和AuAg合金纳米颗粒修饰在BiOBr纳米片表面,获得Au/BiOBr、Ag/BiOBr和具有不同Au/Ag原子比的AuAg/BiOBr复合光催化剂。通过XPS、HRTEM和Mapping表征,充分证实贵金属纳米颗粒均匀地分布在BiOBr表面。利用紫外-可见光漫反射光谱观察到复合光催化剂中贵金属纳米颗粒的表面等离子体共振(SPR)效应。以染料(酸性橙7(AO7)和罗丹明B(RhB))以及Cr(Ⅵ)作为目标反应物,在模拟太阳光照射下对产物的光催化降解和还原性能进行了考察。结果表明:相比于BiOBr单体,Au/BiOBr、Ag/BiOBr和AuAg/BiOBr复合材料的光催化效率均得到提升,其中Au_(0.4)Ag_(0.6)/BiOBr复合物的光催化效果最佳。借助电化学和荧光光谱测试,证明在AuAg/BiOBr复合物中实现了光生电子和空穴的高效分离。光催化循环实验表明Au_(0.4)Ag_(0.6)/BiOBr复合物具有良好的光催化和结构稳定性。基于以上实验结果,提出了AuAg合金纳米颗粒对BiOBr纳米片光催化性能的改性机理。

BiOBr nanoplates were prepared through the hydrothermal method,and then Au,Ag and AuAg alloy nanoparticles were decorated on the surface of BiOBr nanoplates by photoreduction route,leading to the formation of Au/BiOBr,Ag/BiOBr and AuAg/BiOBr composites with different Au/Ag atomic ratio.The XPS,HRTEM and Mapping characterization results show that the noble metal nanoparticles were uniformly distributed on the BiOBr nanoplates surface.The surface plasmon resonance(SPR)effect of noble metal nanoparticles was observed in the ultraviolet-visible diffuse reflectance spectra.Acid orange 7(AO7),Rhodamine B(RhB)and Cr(Ⅵ)were selected as the target reactant,and then the photocatalytic degradation and reduction activity of products were evaluated under simulated sunlight irradiation.The experimental results indicate that the photocatalytic activity of Ag/BiOBr,Au/BiOBr and AuAg/BiOBr are much higher than that of BiOBr nanoplates.Among them,the Au_(0.4)Ag_(0.6)/BiOBr composite exhibits optimal photocatalytic efficiency.The efficient seperation of photogenerated electrons and holes in the AuAg/BiOBr composite was demonstrated by using electrochemical and fluorescence measurement.The photocataltyic cyclic experiment reveals that Au_(0.4)Ag_(0.6)/composite has good photocatalytic and structural stability.Based on above results,the modification mechanism of AuAg alloy nanoparticles on the photocatalytic activity of BiOBr nanoplates was proposed.