钡镧共掺杂对TaON降解亚甲基蓝染料的影响

Effect of Ba-La co⁃doping on degradation of methylene blue dye by TaON

采用改进的溶剂热-高温氮化法制备了钡镧共掺杂的氮氧化钽(TaON)光催化剂。利用XRD、SEM、XPS等手段对其晶相结构、微观形态和光学特性进行了分析,并通过降解亚甲基蓝(MB)溶液来评估其光催化性能。结果表明:Ba、La共掺杂未改变TaON的晶相结构,但其均以离子的形式取代了TaON晶格中的部分Ta^(5+),使TaON的形貌出现轻微变化;共掺杂后的TaON具有更小的晶粒尺寸和更窄的带隙,进一步提高了光吸收能力和光生载流子分离效率;共掺杂后的TaON在可见光下对MB的降解效率大幅提高,当n(Ba)/n(La)为1.00时,TaON光催化性能最佳,120min内对MB的降解率达到86.5%,较纯TaON提升约25%,且反应符合一级动力学规律;此外,h^(+)和·OH是降解MB过程中的主要活性自由基,且经4次循环后其仍具有较好的稳定性和催化性能。

Ba-La co-doped TaON photocatalysts were prepared by an improved solvothermal-high temperature nitridation method.The crystal structure,micromorphology and optical properties were analyzed by XRD,SEM,XPS,and the photocatalytic performance was evaluated by degradation of methylene blue(MB)solution.The results showed that Ba and La co-doping did not change the crystalline structure of TaON,but both of them replaced part of Ta^(5+) in the TaON lattice with ions,which resulted in slight changes in the morphology of TaON.The co-doped TaON had a smaller grain size and a narrower band gap,which further improved the light absorption ability and photogenerated carrier separation efficiency.The degradation efficiency of the co-doped TaON for MB under visible light was dramatically improved,and the best TaON photocatalytic performance was achieved when n(Ba)/n(La)was 1.00,with the degradation rate of MB reaching 86.5%in 120 min,which was about 25%higher than that of pure TaON,and the reaction was conformed to the first-order kinetic law.In addition,h^(+) and·OH were the main active radicals in the degradation process of MB solution,and it still had good stability and catalytic performance after four cycles of catalysis.