Single step strategy to prepare highly microporous carbons derived from melamine and terephthalaldehyde for high-performance material-based hydrogen storage

Abstract

Future energy sources like hydrogen (H2) have been viewed as a viable substitute for fossil fuels. To develop a sustainable H2 economy, efficient means of storing H2 is an urgent prerequisite. In this regard, materials-based H2 storage is a promising route to achieve United States Department of Energy goals. In the current work, a mixture of “melamine and terephthalaldehyde” undergoes simultaneous polymerization, carbonization, and in-situ activation in the presence of molten salt media (KOH + NaOH) by a single all-in-one approach to create microporous carbons with large specific surface areas (SSA ∼ 2462 m2/g), and total pore volume (∼1.96 cm3/g). As-prepared carbons with excellent textural features activated at 800 °C exhibit remarkable H2 storage capacities (up to 3.62 wt% at −196.15 °C and 1 bar, and 6.41 wt% at 30 bar). The results illustrated that pore size (0.68 nm) plays the dominant role in deciding H2 storage capacity at low pressure in comparison to total SSA and micropore volume. However, greater SSA and larger pores are thought to be the determining parameters for measuring H2 storage capacity at higher pressure (30 bar). Lastly, moderate values of isosteric heat of adsorption (Qst = 5.51–7.99 kJ/mol) demonstrate that H2 storage occur through physisorption.