Construction of Benzodithiophene-Based Donor–Acceptor-Type Covalent Triazine Frameworks with Tunable Structure for Photocatalytic Hydrogen Evolution

Abstract

The introduction of donor–acceptor (D–A) motifs into organic semiconductors has been considered as one of the effective strategies to regulate photocatalytic activity. Herein, D–A-type benzodithiophene-based covalent triazine framework materials (BDT-CTFs) have been reported. It has been shown that the valence band and conduction band positions, band gaps, and electron–hole separation efficiency can be adjusted by altering the D/A ratio in the BDT-CTF photocatalytic materials. It has been revealed that the high electron–hole separation, migration efficiency, and low electron–hole recombination rates, as well as the special D–A pore structures are the main reasons for the higher photocatalytic hydrogen evolution reaction (HER) activities of BDT-CTF-1 materials. This work revealed the structure–activity relationship in BDT-based CTFs with different D–A ratios, providing a strategy to develop organic photocatalysts with high performance.

Strategies to improve the photocatalytic performance of covalent triazine frameworks

“…A series of BDT-based CTFs were synthesized to investigate the structure-activity relationship in these materials with different D-A ratios. 93 The experimental results showed that an appropriate D-A ratio in BDT-based CTFs led to efficient charge separation and low electron-hole recombination rates, which greatly promoted the photocatalytic activity for the HER.…”

“…Notably, in these D-A CTF materials, the role of triazine can vary, acting as either an electron donor or acceptor within the CTF structure, owing to the various electronic properties between triazine and the aforementioned moieties. 85,87,[91][92][93] Thiophene or benzothiadiazole (BT) units have been introduced as dopants to enhance the charge carrier separation and migration in CTF-based photocatalysts. Experimental results and density functional theory (DFT) calculations have demonstrated that CTFs modied with Th or BT exhibit extended absorption of visible light and more efficient charge carrier transfer compared to pristine CTF-1.…”

“…The strategic modification of CTFs with donor–acceptor (D–A) units can enable the fine-tuning of their properties and facilitate anisotropic charge carrier migration, thereby enhancing the photocatalytic activity of CTFs. Recent studies have explored various D–A units, such as thiophene (Th), 36,84,85 thieno[2,3- b ]thiophene, 86 phenyl, 87 amide, 88 benzodifuran (BDF), 89 naphthalene, 90 carbazole, 80,91 triphenylamine, 92 benzodithiophene (BDT), 93 phenothiazine (PTZ) 94 as electron donors and benzothiadiazole (BT) 80,84 as an electron acceptor to design CTFs for photocatalytic applications (Table 2). Notably, in these D–A CTF materials, the role of triazine can vary, acting as either an electron donor or acceptor within the CTF structure, owing to the various electronic properties between triazine and the aforementioned moieties.…”

“…Notably, in these D–A CTF materials, the role of triazine can vary, acting as either an electron donor or acceptor within the CTF structure, owing to the various electronic properties between triazine and the aforementioned moieties. 85,87,91–93…”

Regulating the Content of Donor Unit in Donor–Acceptor Covalent Triazine Frameworks for Promoting Photocatalytic H2 Production

“…[15][16][17][18][19] And with triazine moieties as inherent acceptors, the construction of donor-acceptor configuration in CTFs has been regarded as one of the most convenient and effective methods to achieve this goal. [20][21][22][23][24][25] However, most of the published studies have focused on qualitatively investigating the effects of various donor groups on the catalytic properties of CTFs, while few reports have quantitatively investigated the effects of donor unit content (Dcontent) on the optical properties and photocatalytic activities of CTFs.…”