期刊
SCIENCE CHINA-CHEMISTRY
卷 63, 期 8, 页码 1134-1141出版社
SCIENCE PRESS
DOI: 10.1007/s11426-020-9766-5
关键词
photocatalytic water splitting; covalent organic frameworks; first-principles calculations; halogen substitution
资金
- National Natural Science Foundation of China [21688102]
- National Key Research and Development Program of China [2016YFA0200604]
- Anhui Initiative in Quantum Information Technologies [AHY090400]
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-dependentab initionon-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.
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