Halogen modified two-dimensional covalent triazine frameworks as visible-light driven photocatalysts for overall water splitting

• 作者: Cen-Feng Fu Chuanyu Zhao Jin Zhao Jinlong Yang Qijing Zheng Xingxing Li
• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2020,（8）
• 所属期刊栏目: ARTICLES
• 页码范围: 1134-1141
• 页数: 8页
• 语种: 英文

摘要

The covalent triazine framework CTF-1 as a member of the two-dimensional covalent organic frameworks (COFs) is a category of novel metal-free photocatalysts for water splitting.The large band gap severely restricts its energy conversion efficiency.By means of the first-principles calculations,we proposed the decoration of CTF-1 by anchoring halogen atoms onto benzene moieties for improving the solar-to-hydrogen (STH) efficiency.The electronic structures reveal that the halogen substitution successfully decreases the band gap of CTF-1.Meanwhile,the calculated free energy changes along the reaction pathway indicate that all these COFs can spontaneously drive overall water splitting under light irradiation in a specific acid-base environment.The time-dependent ab initio non-adiabatic molecular dynamics simulations suggest that the electron-hole recombination periods of these COFs fall in a few to tens of nanoseconds.Excitingly,CTF-1 modified by linking six iodine atoms onto the benzene ring in the para-position (CTF-1-6I) shows a quite low band gap of 2.81 eV,indicating that it is a visible-light driven COF for overall photocatalytic water splitting.Correspondingly,CTF-1-6I also exhibits an extraordinarily promising STH efficiency of 3.70％,which is an order magnitude higher than that of the pristine CTF-1.