光场作用下Bi基氧化物的能带结构和交换光电流密度研究

发布时间：2019-04-19 17:35

【摘要】：能带结构是从热力学层面判断半导体光催化材料是否具有催化活性的重要参数,其在暗场和光场作用下的精确测定是其准确评价材料催化性能的前提。与热力学相比,动力学活性则决定了材料的实际催化效率。针对光场作用下能带结构的精确测定和光催化动力学参数的确定等问题,本论文以制备的铋(Bi)基氧化物为研究体系,对其进行UV-VisDRS、XRD、SEM、TEM及XPS等测试,获得材料的禁带宽度、晶体结构、表面形貌及表面组成性质。基于光电化学测试技术并结合材料的上述理化测试数据及结果,拟建立在光场作用下以塔菲尔(tafel)曲线为核心的平带电位及材料n、p性质的测试方法,并提出基于交换光电流密度的光催化动力学活性评价方法,与半导体光催化材料的实际光催化性能相比较检验其可靠性和有效性。Tafel曲线表明在光照下α-Bi2O3、β-Bi203、Bi2S3、BiOCl和BiP04均属于n型半导体,但是其导带位置相对于在暗场下依据莫特肖特基(Mott-Schottky)曲线测得的导带位置均发生变化。对比Bi基氧化物在不同光照条件下的交换光电流密度得知全光谱下的交换光电流密度最大,说明在全光谱下光生电子-空穴的分离能力更高,有最好的光催化活性,与光电流-时间曲线和交流阻抗谱图的结果一致。通过测试Bi基氧化物的实际光催化性能,发现在全光谱下Bi基氧化物的催化性能最好。说明依据交换光电流密度分析光催化材料的催化性能是可行的。
[Abstract]:The energy band structure is an important parameter to judge whether the semiconductor photocatalytic material has catalytic activity from the thermodynamic level. The accurate measurement of the material under the action of dark field and light field is the premise of the accurate evaluation of the catalytic performance of the material. Compared with thermodynamics, the kinetic activity determines the actual catalytic efficiency of the material. In this paper, the bismuth (Bi)-based oxide was used as the research system to measure the energy band structure and determine the kinetic parameters of photocatalysis. The UV-VisDRS,XRD,SEM,TEM and XPS of bismuth-based oxide were measured in this paper. The band gap, crystal structure, surface morphology and surface composition of the material were obtained. Based on the photochemical testing technique and the above-mentioned physical and chemical data and results of the materials, a method for measuring the flat band potential and the properties of the materials n, p with the Tafel (tafel) curve as the core under the action of the light field is proposed. The evaluation method of photocatalytic kinetic activity based on exchange photocurrent density is proposed, which is compared with the actual photocatalytic performance of semiconductor photocatalyst. The Tafel curve shows that 伪-Bi2O3, 尾-Bi203,Bi2S3, under illumination is reliable and effective. Both BiOCl and BiP04 belong to n-type semiconductors, but their conduction band positions change relative to those measured according to Mott-Schottky curves in dark field. Compared with the exchange photocurrent density of Bi-based oxides under different light conditions, the exchange photocurrent density is the highest in the whole spectrum, indicating that the photogenerated electron-hole separation ability is higher in the whole spectrum and has the best photocatalytic activity. The results are consistent with the photocurrent-time curves and AC impedance spectra. By testing the actual photocatalytic properties of Bi-based oxides, it is found that the Bi-based oxides have the best catalytic performance in the whole spectrum. It shows that it is feasible to analyze the catalytic performance of photocatalytic materials based on the exchange photocurrent density.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

【参考文献】