g-C3N4纳米带的电子结构及光学性质的第一性原理计算

采用密度泛函理论的第一性原理方法研究了扶手椅型g-C₃N₄纳米带（AC-g-C₃N₄NRs）和锯齿型g-C₃N₄纳米带（ZZ-g-C₃N₄NRs）的电子结构和光学性质。结果表明：AC-g-C₃N₄NRs和ZZ-g-C₃N₄NRs的边缘H原子均能稳定存在。AC-g-C₃N₄NRs的价带顶主要由多数N原子贡献，而ZZ-g-C₃N₄NRs的价带顶主要由CH边缘附近的N原子贡献。AC-g-C₃N₄NRs的导带底主要属于纳米带一侧边缘或两侧边缘附近的C原子和N原子，而ZZ-g-C₃N₄NRs导带底主要属于ZZ-g-C₃N₄NRs的NH边缘附近的C原子和N原子。AC-g-C₃N₄NRs和ZZ-g-C₃N₄NRs的吸收系数和反射率都随纳米带宽度的增加而增加。随着AC-g-C₃N₄NR宽度的增加，吸收系数在低能区域产生明显的蓝移现象。

First-Principles Calculations on Electronic Structures and Optical Properties of g-C3N4 Nanoribbons

The first-principles method based on density functional theory was performed to investigate the electronic structure and optical properties of the armchair nanoribbons (AC-g-C₃N₄NRs) and zigzag g-C₃N₄ nanoribbons (ZZ-g-C₃N₄Rs). The results show that the edge H atoms of AC-g-C₃N₄NRs and ZZ-g-C₃N₄NRs can exist stably. The valence band maximums (VBMs) of AC-g-C₃N₄NRs are mainly contributed by most of N atoms, whereas the VBMs of ZZ-g-C₃N₄NRs are contributed by the N atoms near the CH edge. The conduction band minimums (CBMs) of AC-g-C₃N₄Rs mainly belong to C and N atoms near the one edge or two edges of AC-g-C₃N₄NRs, while the CBMs of ZZ-g-C₃N₄Rs mainly belong to C and N atoms near the NH edge of ZZ-g-C₃N₄NRs. The absorption coefficient and the reflectivity of AC-g-C₃N₄NR or ZZ-g-C₃N₄NR increased with the increasing width of the corresponding nanoribbon. An obvious blueshift phenomenon of the absorption coefficient could be generated in the low-energy range as the width of AC-g-C₃N₄NR increased.