Two-dimensional covalent organic framework films prepared on various substrates through vapor induced conversion.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35301302.
- Also identified by DOI 10.1038/s41467-022-29050-9 and PMC identifier 8931112.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Covalent organic frameworks (COFs) can exhibit high specific surface area and catalytic activity, but traditional solution-based synthesis methods often lead to insoluble and infusible powders or fragile films on solution surface. Herein we report large-area -C=N- linked two-dimensional (2D) COF films with controllable thicknesses via vapor induced conversion in a chemical vapor deposition (CVD) system. The assembly process is achieved by reversible Schiff base polycondensation between PyTTA film and TPA vapor, which results in a uniform organic framework film directly on growth substrate, and is driven by π-π stacking interactions with the aid of water and acetic acid. Wafer-scale 2D COF films with different structures have been successfully synthesized by adjusting their building blocks, suggesting its generic applicability. The carrier mobility of PyTTA-TPA COF films can reach 1.89 × 10<sup>-3</sup> cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup>. When employed as catalysts in hydrogen evolution reaction (HER), they show high electrocatalytic activity compared with metal-free COFs or even some metallic catalysts. Our results represent a versatile route for the direct construction of large-area uniform 2D COF films on substrates towards multi-functional applications of 2D π-conjugated systems.