Hollow sp2-conjugated covalent organic framework encapsulating
thiophene-based photosensitizer for enhanced visible-light-driven
hydrogen evolution
Abstract
Vinylene-linked covalent organic frameworks (COFs) have gained
increasing attention for photocatalytic hydrogen evolution. However, the
photocatalytic activity of vinylene-linked COFs has been restricted due
to low exciton dissociation efficiency and wide band gap. Herein, we
fabricated a novel p-n type Z-scheme heterostructure, g2T-T@HCOFs,
through the hybridization of vinylene-linked COFs with a hollow
structure and thiophene-based photosensitizer (g2T-T) using a template
method and post-encapsulating modification. The hollow-structured HCOFs
enable uniform encapsulation of the g2T-T both within their channels and
on their surfaces, which facilitates the formation of a firm and stable
interface between n-type HCOF and p-type g2T-T. Therefore, the
encapsulation of g2T-T enables the realization of a Z-scheme pathway for
efficient charge separation and transfer, leading to enhanced electron
accumulation within the HCOFs during water splitting. Consequently, the
obtained p-n type Z-scheme heterostructure g2T-T@HCOFs exhibit a
remarkable 5.5-fold enhancement in visi-ble-light-induced hydrogen
evolution activity compared to the pristine COF.