Synthesis of highly porous covalent organic frameworks for green hydrogen storage applications

Abstract

Background

Hydrogen is a clean energy source that is commonly available in the natural world. As an alternative energy option, hydrogen proves exceptionally valuable as green fuel. Hydrogen fuel cells further contribute to unprecedented vehicle efficiencies. One of the main obstacles to hydrogen's widespread use as an energy source is its safe and effective storage. Because of their intrinsic characteristics, COF-MTF stands out as a new family exhibit notable flexibility and a porous structure making them versatile for hydrogen storage and clean energy applications.

Methods

This study aimed to develop an innovative Covalent Organic Framework based on melamine-terephthalaldehyde (COF-MTF) for efficient and sustainable hydrogen storage. The COF-MTF was prepared by directly reacting melamine with terephthalaldehyde through a schiff base reaction. Characterization of the sample was conducted using various techniques, including thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis.

Significant findings

The synthesized COF-MTF networks demonstrated a significant BET surface area of 1986 m².g^-1. It demonstrated notable isosteric heat of adsorption values between 28.7 and 33.5 kJ/mol and achieved a maximum N₂ uptake of 171 mg (N₂)/g at 298 K and 25 atm. Subjected to repeated cycles of H₂ gas adsorption, COF-MTF highlighted exceptional adsorbent stability, maintaining over 99.9 % of its adsorption capacity after 10 cycles. The calculated isosteric heat of hydrogen adsorption by the COF-MTF compound equals 8.447 KJ.mol⁻¹. With relatively high H₂ uptake, this study highlighted COF-MTF as a promising candidate for advancing green hydrogen storage technologies to achieve sustainable development goals (SDGs).