This study aims to enhance the hydrogen storage capacity of covalent triazine frameworks (CTFs) by introducing oxygen functionalization.
The research compares the performance of standard CTF-1 with an oxygen-functionalized version, O-CTF, to determine if the modification could improve hydrogen uptake. The researchers synthesized O-CTF by integrating carboxylic acid groups into the framework through an ionothermal nitrile trimerization reaction, which used a carbonitrile monomer. Both CTF-1 and O-CTF were produced using zinc chloride (ZnCl2) at a temperature of 400 °C.
Key Findings
1. Enhanced Hydrogen Storage: O-CTF displayed a notable increase in hydrogen storage capacity, achieving 4.34 wt% at 20 bar and 77 K. This is a 1.61-fold improvement over CTF-1, which stored 2.69 wt% under the same conditions.
2. Non-Covalent Interactions: The study explored non-covalent interactions in hydrogen-rich CTF complexes using density-functional theory (DFT), emphasizing the role of oxygen in increasing interaction sites for hydrogen molecules.
3. Oxygen’s Crucial Role: The high oxygen content in O-CTF, at 27.16 wt%, contributes significantly to enhanced H2 storage capacity by providing additional sites for adsorption through electrostatic and dispersion interactions, alongside its nitrogen content (11.83 wt%).
These results suggest that oxygen functionalization could be a viable strategy to improve the hydrogen storage capabilities of covalent organic frameworks. The enhanced performance of O-CTF presents an advancement in creating materials that can efficiently store hydrogen, addressing a major challenge in hydrogen utilization and contributing to cleaner energy technologies.
