Zn掺杂二维层状δ-Bi2O3纳米片的光催化固氮性能研究

Zn doping 2D Layered δ-Bi2O3 Nanosheets for Photocatalytic Nitrogen Fixation

通过掺杂修饰催化剂形成捕获陷阱,可以有效抑制光生载流子的复合,获得高效的光催化固氮效率。以Bi(NO3)3·5H2O、Zn(CH3COO)2为原料,采用溶剂热法制备了Zn掺杂的δ-Bi2O3光催化剂。采用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)、X射线光电子能谱(XPS)、透射电镜(TEM)、紫外-可见漫反射(UV-VisDRS)等表征手段对其形貌、元素组成、光吸收等性质进行表征。结果表明,利用这种简单的水热合成方法获得2D薄层状结构的Zn-δ-Bi2O3。在常温常压下,研究了Zn-δ-Bi2O3的光催化固氮性能,并考察了Zn的添加量对光催化固氮活性的影响。结果表明,可见光照射3 h, 4wt%Zn-δ-Bi2O3的氨生成量可达301.6μmol·L^–1。采用荧光、光电流、光阻抗等手段探讨了光催化固氮机理,发现掺杂Zn不仅可以促进价带和导带的轨道杂化,拓宽可见光的利用范围,而且可以在δ-Bi2O3表面形成陷阱,降低光生电子和空穴的复合速率,从而提高光催化固氮效率。

Surface traps are formed by doping element into catalyst, which effectively inhibits the recombination of photogenerated carriers and achieves excellent photocatalytic nitrogen fixation performance consequently. Two-dimensional Zn-δ-Bi2O3 nanosheets were prepared via solvothermal method using Bi(NO3)3·5H2O and Zn(CH3COO)2 as raw materials. The morphology, element composition and light-harvesting capability were characterized by XRD, SEM, EDS, XPS, TEM, and UV-Vis DRS. The results show that Zn doping attributs to interstitial deposition, and Zn-δ-Bi2O3 microspheres are assembled from 2D nanosheets. The ability of photocatalytic nitrogen fixation over photocatalyst was explored under room temperature and atmospheric pressure with visible light irradiation. The results show that the ammonia production over 4 wt% Zn-δ-Bi2O3 could reach 301.6 μmol·L–1 after 3 h irradiation. The mechanism of photocatalytic ammonia synthesis was investigated by means of fluorescence, photocurrent and impedance spectra. Zn doping not only broadens the utilization range of visible light-harvesting, but also inhibits the recombination of photogenerated electron-hole pairs, and thus improves the performance of photocatalytic nitrogen fixation.