Rational preparation of cocoon-like g-C3N4/COF hybrids: Accelerated intramolecular charge delivery for photocatalytic hydrogen evolution

• Published in: Applied catalysis. B, Environmental Environmental, 2022-10, Vol.315, p.121568, Article 121568
• Main Authors: Wang, Lei, Lian, Rui, Zhang, Yang, Ma, Xiaolei, Huang, Jingwei, She, Houde, Liu, Chunli, Wang, Qizhao
• Format: Article
• Language: English
• Subjects: Covalent organic frameworks; Hydrogen evolution; ICT; Photocatalysis
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121568

In virtue of the pliable structure and ample pendent amine groups, the metal-free graphic carbon nitride (g-C3N4, abbreviated as CN) in two-dimensional (2D) morphology could be covalently modified by organic materials to modulate its photoelectrical characteristics. In this work, CN is covalently wrapped by a 2D Schiff-base covalent organic framework (COF, denoted as TMP), which is composed of 2,4,6-tris(4-aminophenyl)− 1,3,5-triazine (TAPT), melem and 1,3,5-triformyl phloroglucinol (TP), by means of “one-pot” solvothermal method with a cocoon-like morphology presented (CN/TMP). Given the significant distinction of charge densities between the two constituent units, viz., melem and TAPT, the resultant acceleration of the intramolecular charge transfer (ICT) within the TMP shroud endows the formed integrate with a significantly raised charge delivery and lowered band gap energy (Eg) in comparison to a structure-analogous COF (TM) incorporated hybrid, CN/TM, in which the TAPT monomer is not involved in the TM COF construction. The photocatalytic water-splitting evaluation indicates CN/TMP conducted photocatalysis could provide the hydrogen (H2) production of 102.88 μmol·h−1, about 5.6 and 11.6 times greater than that of CN/TM and CN, respectively. Our modulation strategy at molecular level proffers a new opportunity for the construction of the carbon nitride based hybrids and the regulation in their photoelectric behaviors. [Display omitted] •A COF is in-situ grown on CN by Schiff-base reaction giving a cocoon-like composite (CN/TMP).•The ICT between the TAPT and TP moieties within the TMP shroud of CN/TMP contributes to the accelerated charge delivery.•The photocatalytic H2 evolution conducted by CN/TMP is 102.88 μmol·h−1, obviously higher than that of TMP, CN, or TM/CN.