Tunable Isometric Donor-Acceptor Wurster-Type Covalent Organic Framework Photocathodes

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) are versatile materials with ordered structures, high porosity, and tunable functionalities.
• Photoactive COFs are crucial for energy conversion applications like water splitting.

Purpose of the Study:

• To synthesize and characterize a series of isostructural, photoactive Wurster-type COFs.
• To investigate the effect of varying acceptor strengths in donor-acceptor-donor (D-A-D) Wurster building blocks on COF properties.
• To evaluate the performance of these COFs in photoelectrochemical (PEC) water splitting.

Main Methods:

• Synthesis of D-A-D Wurster building blocks with varying heteroaromatic acceptors.
• Integration of building blocks into 2D COF scaffolds.
• Characterization using X-ray diffraction, photoluminescence spectroscopy, and PEC measurements.
• Fabrication of homogeneous and oriented thin films.

Main Results:

• Achieved highly crystalline, isostructural COFs with uniform morphologies.
• Demonstrated tunable red-shift in film emission exceeding 100 nm.
• Observed doubled current density in PEC water splitting for the COF with the strongest acceptor unit (8.1 μA cm⁻² at 0.2 V_RHE).

Conclusions:

• Wurster D-A-D COFs offer a promising platform for tuning optical properties and enhancing PEC water splitting performance.
• The study highlights the structure-property relationships in COFs for energy applications.
• Further exploration of chemical functionality for improved reactivity and properties is warranted.