A team of researchers, led by Heinrich Heine University Düsseldorf (HHU) and the University of Siegen, have developed a stable covalent organic framework (COF) with potential for large-scale CO2 capture. It is particularly suitable for various applications, including greenhouse gas reduction, due to its solvent-free, scalable synthesis method and water-resistant properties.
The COF is based on a new compound composed of condensed, highly stable phosphonic acids, or polyphosphonates. These simple, organic phosphonic acid building blocks can easily be stacked together by heating them to temperatures of just approx. 200 degrees Celsius. Once joined, they form covalent organic frameworks (COFs) – a class of porous crystalline materials that form scaffold-like structures.
“The special property of these COFs is that, despite the mild synthesis conditions, they exhibit good water and water vapor stability, meaning that – by contrast with compounds developed to date – they can be used in water and electrolytes,” said Dr. Gündoğ Yücesan, Heisenberg Junior Research Group Leader at the Section for Nanoporous and Nanoscale Materials at HHU. “For the first time, a solid-state synthesis process has been developed for COFs, which can be realized completely without solvents. This method enables low-cost, scalable production from kilograms to tonnes, making it more cost-effective compared with other microporous materials.”
Polyphosphonates of this type have great application potential, for both capturing the harmful greenhouse gas carbon dioxide – and with a slight change in pressure – releasing it again. “Such substances are needed for waste gas cleaning and to prevent greenhouse gas emissions,” the authors of the study note.