具有氧空位BixWO6(1.81≤x≤2.01)的第一性原理计算和光催化性能研究  

First principle calculation and photocatalytic performance of Bi_xWO_6(1.81≤x≤2.01) with oxygen vacancies

作　　者：何金云[1,2] 彭代江 王燕舞 龙飞[1] 邹正光[1] He Jin-Yun1,2 Peng Dai-Jiang1 Wang Yan-Wu3 Long Fei1 Zou Zheng-Guang1 1） ＊(Key Laboratory of Nonferrous Materials and New Processing Technology, Ministry of Education, Guilin University of Technology, Guilin 541004, China） 2） （Guangxi Key Laboratory of New Energy and Building Energy Saving, Guilin University of Technology, Guilin 541004, China） 3） （College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China)

机构地区：[1]桂林理工大学,有色金属及材料加工新技术教育部重点实验室,桂林541004 [2]桂林理工大学,广西建筑新能源与节能重点实验室,桂林541004 [3]桂林理工大学环境科学与工程学院,桂林541004

出　　处：《物理学报》2018年第6期177-186,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号：51662005)和广西自然科学基金(批准号：2016GXNSFAA380101)资助的课题.

摘　　要：为了探索影响Bi_2WO_6光催化性能的内在机制,采用密度泛函理论(DFT)计算和实验研究了非化学计量和氧空位对Bi_2WO_6晶体结构、电子结构和显微结构的影响.采用溶剂热法合成了具有氧空位的非化学计量Bi_xWO_6(x=1.81,1.87,1.89,1.92,2.01)光催化剂.DFT计算结果表明,氧空位的存在可显著减小Bi_2WO_6的带隙,有利于光生电子的生成.实验结果表明,当Bi元素的含量小于化学计量比时,Bi_2WO_6的晶体结构发生了微小变形,Bi元素含量对Bi_2WO_6的显微结构影响不大,但会影响产品氧空位的含量和光吸收性能,并有效抑制电子空穴的复合.Bi_(1.89)WO_6产品的光催化性能最佳,可见光照射180 min后,可降解98%的罗丹明B.采用适当方法,使产品具有氧空位和非化学计量是获得高光催化活性材料的一种有效方法.Semiconductor photocatalyst Bi2WO6 has an extensive application prospect in organic contaminant degradation. But its energy band is relatively large and the recombination rate of photon-generated carriers is high, which prohibit its rapid development and applications. Many methods such as ion doping, non-stoichiometry, semiconductor heterojunction have been used to improve the photocatalytic activity of Bi2WO6. But the improvement mechanism is still not very clear. In this paper, by using first principle density functional theory （DFT） calculation, we study the influences of oxygen vacancy on the bond length, charge population, band structure, defect formation energy, and density of states of Bi2WO6. On the basis of DFT calculation results, different non-stoichiometric BixWO6 （x = 1.81, 1.87, 1.89, 1.92, 2.01） products with oxygen vacancies are synthesized through the solvothermal method. The products are characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra photoluminescence spectroscopy, and X-ray Fluorescence. The effects of non-stoichiometric Bi element on crystal structure, chemical composition, the number of oxygen vacancies, microstructure, and photocatalytic properties are investigated and the improvement mechanism of the photocatalytic property is explored. The DFT calculation results reveal that the formation energies of Bi16W8O48 are different for the three kinds of oxygen vacancies and the bond lengths of Bi-O and W-O with one oxygen vacancy decrease a little and the bond populations decrease significantly for the Bi and W atoms adjacent to oxygen vacancy. The existence of oxygen vacancies forms O 2p impurity energy level and significantly reduces the band gap of Bi2WO6. The absorption spectra indicate that the absorption intensities in the visible light increase for the Bi16W8O48 cell with oxygen vacancy defects increasing. The DFT calculation results show that oxygen vacancy defects promote the formation of pho

关 键 词：Bi2WO6 氧空位 晶体结构 光催化材料 

分 类 号：O643.36[理学—物理化学]