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光催化分解水制H_2和光催化还原CO_2是解决能源危机和全球变暖的有效途径.但是,由于粉末光催化剂存在回收效率低的问题,因而光催化成本很高.而磁性光催化剂便于回收和重复利用,因此人们把目光转向具有磁性的非光催化剂材料,试图通过改性使得磁性材料具有合适的水分解或者还原CO_2的氧化还原电位.同时,对具有光催化活性但是没有磁性的材料进行磁化改性可以得到新型的磁性光催化剂.本文通过对本身具有磁性的NiO材料进行Cu掺杂能带调整,使调整后的NiO具有合适的氧化还原电位;对本身具有良好光催化氧化还原电位的CuO材料进行Ni掺杂磁化调整,使磁化后的CuO既有良好的氧化还原电位又有磁性.最终两种材料经过掺杂变成磁性光催化材料,既有较好的光催化性能,又可高效回收,因此有望在光催化领域具有潜在的应用前景.LSDA(局域自旋密度近似)+U(有效库仑相关能)计算方法能够很好地给出磁矩和禁带宽度等电子结构性质.本文通过LSDA+U计算方法对具有磁性的宽禁带半导体材料NiO进行电子结构改性研究,希望通过降低其禁带宽度、调整其氧化还原电位使之对太阳光有响应.因其同时具有磁性便于回收,使得光催化分解水制H_2和光催化还原CO_2成本高的问题得到解决.对NiO的磁胞进行了Cu掺杂计算,结果发现Cu的掺杂几乎没有引起NiO空间结构的变化,这是因为Cu和Ni的离子半径相近.通过对电子结构的计算发现掺杂体系的禁带变窄,并且在禁带中间出现了两条杂质能级,该杂质能级是由掺杂原子Cu 3d态组成.杂质能级的出现能够降低光生载流子在带隙中的复合,从而提高光催化效率.计算结果同时表明,Cu掺杂的NiO系统具有一个1μB的净磁矩,即Cu的掺杂使得NiO显示出磁性,而Ni的磁矩在掺杂前后几乎保持不变,由纯相的1.67μB增加到掺杂体系中的1.70μB.由于CuO本身低指数(111)面和(011)面具有合适的分解水制H_2和还原CO_2的氧化还原电位,如果对CuO进行磁化改性,可以使光催化剂CuO同时带有磁性,便于回收再利用.本文对CuO磁胞进行了Ni的掺杂计算.结果表明,由于离子半径相近,Ni掺杂几乎没有引起CuO空间结构的变化.掺杂后的体系具有一个1.66μB的净磁矩,同时Ni的掺杂引起多个杂质能级出现,靠近价带的杂质能级由Cu 3d态组成,而在导带底位置出现的杂质能级主要由Ni 3d态组成.整个能带向高能级方向平移.
Photocatalytic decomposition of water to H_2 and photocatalytic reduction of CO_2 is an effective way to solve the energy crisis and global warming.But due to the low recovery efficiency of the powder photocatalyst, photocatalytic cost is high, while the magnetic photocatalyst is easy to recover and repeat Therefore, attention has been paid to the non-photocatalyst material having magnetic properties, attempting to modify the redox potential of the magnetic material by modifying it, and at the same time, magnetizing the photocatalytically active but non-magnetic material Can get a new type of magnetic photocatalyst.In this paper, by adjusting the Cu doping energy band of the NiO material with its own magnetic properties, the adjusted NiO has a suitable redox potential; CuO material with good photocatalytic oxidation-reduction potential Ni doping magnetization adjustment so that the magnetized CuO has both a good redox potential and magnetic Finally, the two materials after doping into a magnetic photocatalytic material, both good photocatalytic properties, but also highly efficient recovery , So it is expected to have potential applications in the field of photocatalysis.LSDA (local spin density approximation) + U Related energy) calculation method can well give the electronic structure properties such as the magnetic moment and the forbidden band width.This paper studies the electronic structure modification of a wide band gap semiconductor material NiO with LSDA + U calculation method, Forbidden band width, adjust its redox potential make it to the sunlight response.At the same time with magnetic easy to recover, making the photocatalytic decomposition of water H2 and photocatalytic reduction of high cost CO_2 be solved.On NiO magnetic cell Cu doping calculations, the results show that the doping of Cu almost did not cause changes in the spatial structure of NiO, Cu and Ni because of the similar ion radius. Calculated by the electronic structure of the doped system was found to narrow the band gap, and in the ban There are two impurity levels in the middle of the band, and the impurity level is composed of the doping atoms in the Cu 3d state. The appearance of impurity levels can reduce the recombination of photogenerated carriers in the bandgap and improve the photocatalytic efficiency. It is also shown that the Cu-doped NiO system has a net magnetic moment of 1μB, that is, the doping of Cu makes NiO show magnetism while the magnetic moment of Ni almost keeps unchanged from 1.67μB of pure phase to 1.70μB in CuO system.With the low index (111) plane and (011) plane of CuO itself having the appropriate redox potential for the hydrolysis of H 2 and CO 2, if CuO is magnetized, the photocatalyst CuO can be simultaneously With the magnetic, easy to recycle .In this paper, the NiO doping calculation of CuO magnetic cell was carried out. The results show that the structure of CuO almost does not change due to the similar ionic radius. The doping system has a 1.66 μB. At the same time, the doping of Ni leads to the appearance of several impurity levels. The impurity levels near the valence band are composed of Cu 3d states, while the impurity levels at the bottom of the conduction band mainly consist of Ni 3d states. The whole energy band to the high level of translation.