Photoelectrochemical water splitting with a triazine based covalent organic framework

Abstract

Photoelectrochemical (PEC) water splitting under visible light irradiation is a very promising path for green and sustainable hydrogen production. The PEC process has attracted enormous research interest due to the potential of direct conversion of solar power into chemical fuel. Herein, we present a covalent organic framework (COF), which shows promise as an ideal photoabsorber due to the combination of efficient light harvesting sites with a suitable band gap and catalytic sites for the HER. Under solvothermal conditions, a Schiff base type condensation between 1,3,5-tris(4-formylbiphenyl)benzene (TFBB), 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAT) and 2,4,6-tris(4-aminophenyl)-benzene (TAB) yields crystalline, 2-D covalent organic frameworks TFBB–TAT and TFBB–TAB COFs, respectively. The as-prepared triazine containing TFBB–TAT COF shows better photoelectrochemical (PEC) water splitting compared to the non-triazine based TFBB–TAB COF. This work enriches the structural variety of COFs and plays an important role in PEC water splitting, also illustrating the intriguing electrochemical behaviour of this class of materials.