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

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 (E-g) 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 (H-2) production of 102.88 mu mol.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.

Automated summary

By covalently modifying metal-free graphic carbon nitride with a 2D Schiff-base covalent organic framework, the photoelectrical characteristics and photocatalytic water-splitting efficiency were significantly improved. This modulation strategy at the molecular level provides a new opportunity for constructing carbon nitride based hybrids and regulating their photoelectric behaviors.