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构建同质异相或异质结构是提高光催化材料性能的有效途径之一,尤其是对于CdS这类具有光腐蚀的材料,这种方法还能起到提高光催化材料稳定性的作用。因此目前制备CdS基复合光催化材料得到了广泛的研究,但是目前对其中的一些基本问题和关键因素仍需要进一步探讨和解释。本文采用第一性原理方法对CdS/FeP复合光催化材料中异质结构的界面微观结构和性质进行深入研究。计算结果表明,由于在界面上部分悬挂键被饱和,界面模型呈现出与体相或表面模型不同的电子结构特征,并且有界面态的存在。在CdS/FeP异质结构的界面处,CdS和FeP的能带都相对向下移动,而且FeP的能带(费米能级)插入到CdS的导带下方;同时在界面达到平衡态之后,异质结构的内建电场由FeP层指向CdS层,因而能够实现光生电子-空穴对在CdS/FeP界面处的空间有效分离,这对于光催化性能的增强极其有利。此外,构建CdS/FeP异质结构也能够进一步增强CdS在可见光区的光吸收。本文研究结果为构建具有异质结构的高效复合光催化材料提供了机理解释和理论支持。
The construction of homogeneous heterogeneous or heterogeneous structures is an effective way to improve the photocatalytic properties of materials, especially for photo-corroded materials such as CdS, which can also improve the stability of photocatalytic materials. So far, CdS-based composite photocatalytic materials have been widely studied, but some of the basic problems and key factors still need to be further explored and explained. In this paper, first-principles method for CdS / FeP composite photocatalytic materials in the interfacial microstructure and properties of in-depth study. The results show that due to the saturation of some dangling bonds in the interface, the interface model shows different electronic structure characteristics from the bulk or surface model, and the interface states exist. At the interface of CdS / FeP heterostructures, the bands of CdS and FeP move relatively downward, and the energy band (Fermi level) of FeP is inserted below the conduction band of CdS. At the same time, after the interface reaches the equilibrium state, The built-in electric field of the heterostructure is directed from the FeP layer to the CdS layer, so that an efficient space separation of photogenerated electron-hole pairs at the CdS / FeP interface can be achieved, which is extremely advantageous for the enhancement of the photocatalytic performance. In addition, CdS / FeP heterostructures can be constructed to further enhance the absorption of CdS in the visible region. The results of this study provide a mechanistic explanation and theoretical support for the construction of highly efficient composite photocatalytic materials with heterogeneous structures.