Yang F L, Xia F F, Hu J, Zheng C Z, Sun J H, Yi H B
School of Chemical and Environmental Engineering, Jiangsu University of Technology Changzhou 213001 Jiangsu P. R. China.
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University Changsha 410082 Hunan P. R. China
RSC Adv. 2018 Jan 9;8(4):1899-1904. doi: 10.1039/c7ra12444a. eCollection 2018 Jan 5.
Graphite-like carbon nitride (g-CN) has attracted much attention due to its peculiar photocatalytic performance as a visible-light-responsive photocatalyst. However, its insufficient sunlight absorption is not conducive to the photocatalytic activity of the g-CN. Herein, by using first-principles density functional theory (DFT) calculations, we demonstrated a simple yet efficient way to achieve improvement of photocatalytic activity of monolayer g-CN surface charge transfer doping (SCTD) using the electron-drawing tetracyanoquinodimethane (TCNQ) and electron-donating tetrathiafulvalene (TTF) as surface dopants. Our calculations revealed that the electronic properties of monolayer g-CN can be affected by surface modification with TCNQ and TTF. These dopants are capable of drawing/donating electrons from/to monolayer g-CN, leading to the accumulation of holes/electrons injected into the monolayer g-CN. Correspondingly, the Fermi levels of monolayer g-CN were shifted towards the valence/conduction band regions after surface modifications with TCNQ and TTF, along with the increase/decrease of work functions. Moreover, the optical property calculations demonstrated that the TCNQ and TTF modifications could significantly broaden the optical absorption of monolayer g-CN in the visible-light regions, yielding an improvement in the photocatalytic activity of monolayer g-CN. Our results unveil that SCTD is an effective way to tune the electronic and optical properties of monolayer g-CN, thus improving its photocatalytic activity and broadening its applications in splitting water and degrading environmental pollutants under sunlight irradiation.
类石墨相氮化碳（g-CN）作为一种可见光响应型光催化剂，因其独特的光催化性能而备受关注。然而，其对太阳光吸收不足不利于g-CN的光催化活性。在此，通过第一性原理密度泛函理论（DFT）计算，我们展示了一种简单而有效的方法，即使用吸电子的四氰基对苯二醌二甲烷（TCNQ）和供电子的四硫富瓦烯（TTF）作为表面掺杂剂，通过表面电荷转移掺杂（SCTD）来提高单层g-CN的光催化活性。我们的计算表明，TCNQ和TTF对单层g-CN的表面修饰会影响其电子性质。这些掺杂剂能够从单层g-CN中抽取/给予电子，导致注入到单层g-CN中的空穴/电子积累。相应地，用TCNQ和TTF进行表面修饰后，单层g-CN的费米能级向价带/导带区域移动，功函数增加/减小。此外，光学性质计算表明，TCNQ和TTF修饰可显著拓宽单层g-CN在可见光区域的光吸收，从而提高单层g-CN的光催化活性。我们的结果表明，SCTD是调节单层g-CN电子和光学性质的有效方法，从而提高其光催化活性，并拓宽其在太阳光照射下分解水和降解环境污染物方面的应用。
