氮化硼纳米管-纳米片分级结构的制备及光学和吸附特性

Boron Nitride Nanotube-nanosheet Hierarchical Structures and Its Optical/adsorption Properties

将五硼酸铵、氨硼烷络合物和氧化镁混合,球磨均匀后,在1200℃及0. 6 L/min流动氨气保护条件下退火6 h,即可在氧化铝基片上收集到白色毛状产物.采用X射线衍射(XRD),红外光谱(FTIR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、拉曼光谱(Raman)、紫外-可见吸收光谱(UV-Vis)和荧光光谱(PL)对产物进行了表征.结果表明,样品呈一维线状分级结构,长度大于5 mm,中间为竹节状空心结构,内部管径为50～350 nm,外径范围为200～800 nm.分级结构表面负载了大量氮化硼(BN)纳米薄片,单个薄片厚度约为13 nm.薄片弯曲褶皱,相互交织,构成1个氮化硼片层,其厚度约为50～200 nm. UV-Vis和PL光谱测试结果表明,氮化硼纳米管(BNNT)分级结构在紫外光材料领域具有一定的应用潜力,且对亚甲基蓝具有良好的吸附能力(7 min即可吸附71%,107 min时可吸附96%).对比实验结果表明,BNNT的生长机理遵循气-液-固相(VLS)模型,而表面负载的超薄BN片的生长机理遵循气-固相(VS)模型.

Ammonium pentaborate, ammonia borane and magnesium oxide powder were ball milled and then heated at 1200 ℃ for 12 min in the atmosphere of 50 mL/min ammonia gas. And the white flocculent product was collected on the surface of the alumina substrate. The experimental results indicated that the samples revealed one-dimensional linear hierarchical structures with an average length of more than 5 mm and the outsider diameter of 200-800 nm. And the middle of the hierarchical structure was bamboo-like hollow structure with the inner diameter of 50-350 nm. In addition, abundant BN nanosheets loaded on the surface of the BNNT hierarchical structure and the thickness of single nanosheet was about 13 nm. Lots of nanosheets bended, folded and interweave together to form BN layer with the thickness of 50-200 nm. Besides, UV-Vis and PL analysis demonstrated that the as-synthesized BNNT hierarchical structures could be used in the field of ultraviolet light materials. The BNNT hierarchical structures also presented excellent adsorption property for methylene blue(MB). When the adsorption time was 7 min, MB was removed by 71% from water solution. The adsorption rate increased to 96% when the adsorption time was 107 min. Finally, the comparison experiment indicated that the growth mechanism of BNNT followed the vapour-liquid-solid(VLS) model, but the growth mechanism of the surface-loaded BN nanosheet belonged to vapour-solid(VS) model.