物理化学学报 >> 2014, Vol. 30 >> Issue (1): 43-52.doi: 10.3866/PKU.WHXB201311082

理论与计算化学 上一篇    下一篇

g-C3N4碳位掺杂电学及光学性质的分析

阮林伟1, 裘灵光1, 朱玉俊1, 卢运祥2   

  1. 1 安徽大学化学化工学院, 合肥 230601;
    2 华东理工大学化学与分子工程学院, 上海 200237
  • 收稿日期:2013-08-29 修回日期:2013-11-08 发布日期:2014-01-01
  • 通讯作者: 裘灵光，朱玉俊 E-mail:lgqiu@ahu.edu.cn；675096471@qq.com
  • 基金资助:

    国家自然科学基金(20971001，51002001，20371002)资助项目

Analysis of Electrical and Optical Properties of g-C3N4 with Carbon-Position Doping

RUAN Lin-Wei1, QIU Ling-Guang1, ZHU Yu-Jun1, LU Yun-Xiang2   

  1. 1 College of Chemistry and Chemical Engineering, Anhui University, Hefei 230601, P. R. China;
    2 Department of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
  • Received:2013-08-29 Revised:2013-11-08 Published:2014-01-01
  • Contact: QIU Ling-Guang, ZHU Yu-Jun E-mail:lgqiu@ahu.edu.cn；675096471@qq.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20971001, 51002001, 20371002).

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摘要：

使用第一性原理研究了C位掺杂的g-C3N4的电学性质和光学性质，掺杂原子为B、P、S. g-C3N4有C1位和C2 位两种对称位碳原子，其中在C1 位上的掺杂易于C2 位，掺杂体系也较C2 位稳定. 相比于磷和硫在g-C3N4上的掺杂，硼掺杂最易于进行. 掺杂后体系的晶体结构之间差别较大，这与掺杂原子的大小以及电负性有关. 由轨道布居分布可知，掺杂后的硼、磷、硫原子价电子发生了变化，表明掺杂原子发生了杂化，与相邻原子以强的共价键相连. 掺杂原子与被取代的碳原子之间的价电子差异导致了能带的增加. 在原来的体系中，掺杂后的体系出现了一条新的能带，因此导致实际带隙下降，表明了掺杂后的体系导电性能增强. 对纯g-C3N4及掺杂g-C3N4的光学性质分析表明，g-C3N4的光学吸收主要在紫外光区，掺杂磷和硫后对g-C3N4的光吸收波长范围无改变，掺杂硼后的g-C3N4光吸收不再局限于紫外光区，而且延伸至可见光区和红外光区，并在红外光区有很强的吸收，表明g-C3N4掺杂硼后能大大地提高光催化效率. 电子能量损失光谱和光导率谱以及介电常数都佐证了上述观点.

关键词: 掺杂, g-C3N4, 碳位, 电学, 光学, 第一性原理

Abstract:

Some properties of g-C3N4 with carbon positions doped by B, P, and S atoms were investigated using quantum mechanics (first principles). There are two symmetric carbon atoms in g-C3N4, named C1 and C2. C1 is easier to dope than C2, and the system doped at C1 is more stable. It was found that it is easier to dope g-C3N4 with B than with P and S. There are significant differences among the crystal structures after doping, this is attributed to the sizes and electronegativities of the different doping atoms. The orbital population distributions showed that the electronic valences of the B, P, and S atoms changed when the doping was changed. This shows that hybrid doped atoms linked with adjacent atoms through covalent bonds are present. The differences between the valence electrons of the dopant atoms and the substituted atoms result in new bands after doping. The emergence of a new energy band in the band gap of the original g-C3N4 results in a decreased band gap after doping, indicating that the conductivity of the doped system is higher than that of the non-doped system. Analyses of the optical properties of pure g-C3N4 and doped g-C3N4 show that the optical absorption spectrum of g-C3N4 is mainly in the ultraviolet region, and the wavelength range of light absorption is unchanged after doping with P and S. However, after doping with B, the wavelength range of light absorption extends to the visible and infrared regions. Strong absorption in the infrared region shows that the photocatalytic activity of g-C3N4 after doping with B is much higher than that of undoped g-C3N4. The electron energy loss spectrum, optical conductivity spectrum, and the dielectric function curve support these points.

Key words: Doping, g-C3N4, Carbon-cite, Electricity, Optics, First-principles