Chlorine-mediated photocatalytic hydrogen production based on triazine covalent organic framework

Modification of Covalent Triazine-Based Frameworks for Photocatalytic Hydrogen Generation

“…The energy of photogenerated holes was predicted between +2 eV and +1.2 eV (vs. NHE), which were able to oxidize water to form molecular oxygen. To improve the efficiency of photocatalytic hydrogen generation and investigate the relationship between the catalyst structure and performance, as presented in Figure 9 , a great number of modification strategies have been performed to optimize the band structure [ 12 , 14 , 20 , 35 , 36 , 37 , 38 , 39 , 40 ] and charge dynamic process [ 10 , 15 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ], thus broadening the visible light absorption, enhancing the driving force of hydrogen generation, and improving the transport and separation efficiency of photocharges.…”

“…This could partially be explained by the halogen atoms doped samples. When treating CTF-1 with HCl, Cl atoms were successfully doped in the position between the C-N bond, showing much lower activity than the undoped sample [ 38 ]. On the contrary, when treated CTF-1 by NH 4 Cl, Cl atoms were only able to substitute H atoms in benzene motifs.…”

“…According to electrochemical impedance spectroscopy and photoluminescence spectroscopy, the charge transfer of the composite was much stronger than that of two single materials, CdS and CTF-1. Using lactic acid as the sacrificial agent, the hydrogen evolution rate was 243 µmol h −1 (>420 nm), which was three times higher than that achieved by CdS nanoparticles [ 38 ]. Furthermore, as both conduction and valence band positions of CTF-1 were more positive than that of CdS, photogenerated electrons were directed to the conduction band of CdS, while photoholes transferred to the valence band of CTF-1, which effectively avoid the oxidative corrosion of CdS by photoholes.…”

Light-Driven Hydrogen Evolution Assisted by Covalent Organic Frameworks

“…The ethylene bridge formed between two cationic adjacent N atoms (Tp-2C/Bpy 2+ -COF) acts as an integrated electron mediator, resulting in a concomitant increase in photocatalytic HER activity when combined with a Pt co-catalyst [35]. Another post-functionalization strategy has also been reported recently, in which a CTF-COF has been treated in HCl after having been exfoliated by ball-milling, thus generating the formation of Cl-intercalated CTF-1 through Cl-C and Cl-N covalent bonds within the triazine ring [36]. The formed COF interlayer channels facilitate charge separation and mobility as well as a narrowing of the bandgap, therefore enhancing its light absorption and photocatalytic HER capabilities.…”

Two‐Dimensional Covalent‐Organic Frameworks for Photocatalysis: The Critical Roles of Building Block and Linkage

“…Similarly, as a nitrogen‐rich photo‐responsive block, the triazine block offers high electron mobility and can be incorporated into a 2D COF by the polymerization reaction of cyano, [ 72–81 ] or the use of triazine‐based monomers. Covalent triazine frameworks (CTFs) as a representative subclass of 2D COFs with triazine blocks exhibit lower crystallinity and diversity because of their harsh synthesis conditions and limited building monomers, whereas 2D COFs constructed by triazine‐based monomers are obtained easily under mild conditions and demonstrate good photocatalytic activity.…”