不同晶相LaPO4纳米棒对光催化性能的影响

摘要

Rare earth phosphate has a wide application in optical materials,laser materials and many fields with great develop-ment prospects.In this paper,LaPO4 nanorods with different crystalline phases are prepared with hydrothermal method,its photocatalytic performance are discussed,as well as the structure and UV diffuse reflectance spectroscopy.The research indi-cates that the hydrothermal temperature plays a key role in the crystal phase,while it is hexagonal at 120 ℃,monoclinic at 180℃ and the mixed phase at 160 ℃.The UV absorption has no obvious change of each crystalline phase,and they all show nano-rods.The photocatalytic activity of LaPO4 for the degradation of MB is studied;it is found that the monoclinic LaPO4 has the best photocatalytic activity.Furthermore,monoclinic LaPO4 could decrease the fluorescence quantum efficiency and increase the separation efficiency of electrons and holes,which improve the photocatalytic activity.Besides,the main active species are con-firmed to be hydroxyl radicals with capture experiments during the photocatalytic process.%稀土磷酸盐在光学材料、激光材料等许多领域有着广泛的利用,具有较大的开发前景。通过水热法制备出不同晶相的 LaPO4纳米棒,重点研究了其在光催化领域的应用,并对其结构以及紫外漫反射光谱进行了分析讨论。研究表明水热温度是影响其晶相的一个关键因素,120℃时为六方相,160℃时为六方与单斜混合相,而温度提高至180℃时为单斜相。不同晶相 LaPO4对紫外光吸收没有明显的区别,且各晶相下均为纳米棒结构。通过光催化降解亚甲基蓝(MB)来研究不同晶相 LaPO4光催化活性区别,发现单斜相的LaPO4纳米棒具有更高的光催化活性。研究进一步发现,单斜相的LaPO4纳米棒可促进荧光量子效率降低,提高了光生电子及空穴的分离效率,因而光催化降解 MB活性较高。此外,利用活性物种捕获实验,确定了单斜相 LaPO4在光催化降解过程中起主要作用的活性物种为羟基自由基。