The electronic and optical properties, including band structure, density of states (DOS), absorption rate, refractive index, and dielectric function, of anatase TiO2 codoped with N and first transition elements are investigated using the plane wave pseudopotential method based on the density functional theory. The calculation results show that TiO2 codoping with N and first transition elements (Sc, V, Cr, Mn, and Fe) lead to significant reduction of conduction band relative to the Fermi level, reduction of band gap width, formation of new donor, and acceptor impurity levels below the conduction band and above the valence band, and cause some redshifts of optical absorption band edge with the amount of redshift decrease in the following order: N–Fe > N–Cr > N–Mn. Further, the synergistic effect of shallow donor and acceptor levels enhances light excitation for effective separation of electron–hole pairs and enhancement of light absorption ability, thereby increasing the TiO2 photocatalytic properties. This study reveals that the visible-light absorption ability of the codoped anatase TiO2 decreases in the order of N–Fe > N–Cr > N–Mn > N–Sc > N–V > N, and does not monotonically follow the dopant atomic number. Especially, in N–Cr codoped TiO2, the 4s atomic orbit of Cr is not completely filled, which hybridized with the p electronic orbit most probably acts as photo-generated electron trap centers resulting in higher photocatalytic activity than that of N–Mn codoped TiO2.

选用体积分数为99.999 9%的H2及反式-2-丁烯(T2B)为工作气体,利用低压等离子体增强化学气相沉积法制备了α-C:H薄膜。利用傅里叶变换红外光谱仪和X射线光电子能谱对薄膜化学键和电子结构进行分析,并结合高斯分峰拟合分析了薄膜中sp3/sp2杂化键比值和sp3C杂化键分数。结果表明:薄膜中氢含量较高,主要以sp3C-H形式存在;工作气压越高,制备的薄膜中C=C键含量越少,薄膜中sp3/sp2杂化键比值和sp3C杂化键分数增加,薄膜稳定性提高。应用UV-VIS光谱仪,获得了波长在400～1 000 nm范围内薄膜的光吸收特性,结果显示:α-C:H薄膜透过率可达98%。光学常数公式计算得到工作压强为4-14 Pa时光学带隙在2.66～2.76之间,并均随着工作气压的升高而增大。结果表明,随工作气压的升高,薄膜内sp3键减小,从而促使透过率、光学带隙增大。