氮掺杂HTi2NbO7纳米片的制备及其可见光催化性能

Synthesis and Visible-Light-Driven Photocatalytic Activity of Nitrogen-Doped HTiNbO Nanosheet

首先,采用高温固相法制备层状前驱体CsTi2NbO7,再通过与硝酸进行质子交换形成层状HTi2NbO7;其次,在四丁基氢氧化铵(TBAOH)中剥离层状HTi2NbO7以获得HTi2NbO7纳米片;然后与尿素混合并高温焙烧;最后成功地得到了氮掺杂的HTi2NbO7纳米片光催化剂。使用粉末X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)、紫外-可见漫反射吸收光谱(UV-Vis DRS)以及N2吸附-脱附测试等方式对所制备样品的晶体结构、形貌、比表面积、孔分布和光吸收能力等进行详细的表征。研究表明,氮掺杂后减小了HTi2NbO7的禁带宽度,从而使光响应范围扩展到可见光区域;掺杂的氮原子主要位于Ti2NbO7-薄片的间隙位置,并与氢离子化学键合;与N掺杂的层状HTi2NbO7相比,N掺杂的HTi2NbO7纳米片具有更大的比表面积和更丰富的介孔结构,这是由于钛铌酸纳米片相对松散且不规则的排列。因此,在降解罗丹明B(RhB)溶液时,N掺杂的HTi2NbO7纳米片比N掺杂的层状HTi2NbO7具有更加优异的可见光催化活性。

Firstly,layered CsTi2NbO7 was prepared by high temperature solid-state method,and then layered HTi2NbO7 was obtained by a proton-exchange reaction treated with HNO3 solution.Secondly,the obtained layered HTi2NbO7 was well dispersed in tetrabutylammonium hydroxide(TBAOH)solution in order to prepare HTi2NbO7 nanosheets by exfoliation reaction.Thirdly,the as-prepared HTi2NbO7 nanosheets were dried,and then mixed with urea.Finally,nitrogen-doped HTi2NbO7 nanosheet photocatalyst was successfully synthesized by heating the above mixture.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),high resolution transmission electron microscopy(HRTEM),X-ray photoelectron spectroscopy(XPS),Ultra-violet-Visible diffuse reflectance absorption spectrum(UV-Vis DRS)as well as N2 adsorption-desorption measure-ments to characterize the crystal structure,morphology,specific surface area,pore distribution and light absorption capacity of as-prepared samples in detail.It was found that the doped nitrogen resulted in an intrinsic narrowing band-gap so as to widen light response region,and the doped nitrogen atoms were mainly located at the interstitial position of Ti2NbO7-sheets and chemically bonded with hydrogen ions.Moreover,compared with N-doped HTi2NbO7,N-doped HTi2NbO7 nanosheets had a larger specific surface area and richer mesoporous structure due to the relatively loose and irregular arrangement of the titanium niobate nanosheets.Therefore,the N-doped HTi2NbO7 nanosheets exhibited higher visible-light photocatalytic activity for degradation of RhB than that for N-doped lay-ered HTi2NbO7.