Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (1): 43-52.

• THEORETICAL AND COMPUTATIONAL CHEMISTRY •

### 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).

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.

MSC2000:

• O641