多层级花状W掺杂BiVO_4的水热法制备与光催化性能

Hierarchical Flower-like W Doped BiVO_4 Hydrothermal Synthesis and Enhanced Photocatalytic Efficiency

以Bi(NO_3)_3、Na_3VO_4、Na_2WO_4为原料,以SDS为结构导向剂,采用水热法制备了W掺杂BiVO_4。利用XRD、SEM、TEM、HRTEM以及紫外-可见漫反射光谱(UV-vis)对样品进行结构、形貌及光吸收性能分析。结果表明:W掺杂单斜相BiVO_4具有由纳米片组装而成的多层级花状结构,这种结构具有较大的比表面积,可增加样品对光的吸收。SDS在BiVO_4(100)晶面的选择性吸附是花状结构形成的关键原因。W掺杂能有效提高BiVO_4的光催化活性,当W掺杂浓度为2.5%时,样品对MB的光催化活性最高。这是因为当适量的W离子进入BiVO_4晶格并实现V位替代后,导致BiVO_4发生晶格畸变,增大了BiVO_4内电势,并在BiVO_4的禁带内引入了施主能级,促进了BiVO_4光生电子与空穴的分离,提高了BiVO_4的量子效率。

In the present study, W doped BiVO4 with hierarchicai flower--like shape was synthesized via a SDS assisted hy- drothermal approach with Bi{NOa ）a , Na3VO4 , and Na2WO4 as starting materials. XRD, SEM, TEM, HRTEM, XPS and UV--vis were apllied for characterization of the as prepared samples. The results showed that the hierarchical flowerlike structures of W doped BiVO4 were actually formed by the oriented assembly of nanosheets. The selective adsorption of SDS on the {100） facet of givo4 played a key role in the formation and oriented assembly of nansheets. W doping effective- ly improved the photocatalytic efficiency of BiVO4 for degradation of MB under visible light irradiation. The substitution of V by W in BiVO4 resulted in the crystal distortion and introduced the donor level into the band gap of BiVO4, improving the quantum yield of BiVO4.