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采用基于密度泛函理论超软赝势平面波方法的第一性原理计算了纯锐钛相Ti O2和非金属(B,C,N,F,P,S,Cl)掺杂体系的晶体结构、电子结构和光学性质。计算结果表明,非金属掺杂后由于晶格常数、键长、原子电荷分布的变化导致Ti O2的八面体偶极矩增大,这对光生电子-空穴对的分离是十分有利的。由掺杂物的p电子态与O的2p电子态、Ti的3d电子杂化而形成的杂质能级的存在使大多数掺杂体系的带隙减小,从而使Ti O2的基本吸收带边红移到可见光区。根据理论结果,系统分析和比较了非金属对锐钛矿相Ti O2电子结构和光学性质的掺杂效应,同时非金属掺杂对Ti O2光催化材料在可见光激发下的作用也得到了分析。计算结果解释了部分非金属掺杂可以使锐钛矿相Ti O2在可见光激发下具有较高光催化活性的原因。
The crystal structure of pure anatase phase Ti O2 and nonmetallic (B, C, N, F, P, S, Cl) doping systems was calculated by the first principle based on the super soft pseudopotential plane wave method of density functional theory. Electronic structure and optical properties. The calculated results show that the octahedral dipole moment of Ti O2 increases due to the lattice constant, bond length and atomic charge distribution after the non-metallic doping, which is very beneficial for the photo-electron-hole pair separation. The bandgap of most of the doping systems is reduced by the impurity level formed by the p electron state of the dopant and the 2p electron state of O and the 3d electron hybridization of Ti, Red shift to the visible area. According to the theoretical results, the doping effect of nonmetal on the electronic structure and optical properties of anatase phase Ti O2 was systematically analyzed and compared. The effect of nonmetal doping on the photocatalytic activity of Ti O2 under visible light excitation was also analyzed. The calculation results explain that some non-metallic doping can make the anatase phase Ti O2 have higher photocatalytic activity under visible light excitation.