Amine-modified MOF-14 as a tunable platform for CO2 adsorption and supercapacitor energy storage

Abstract

Amine-functionalized copper(ii)-based MOF-14 materials were prepared via post-synthetic modification using ethylenediamine (en), diethylenetriamine (deta), and 1,2-bis(3-aminopropylamino)ethane (bape) at varying incorporation levels. Comprehensive structural, morphological, textural, and thermal analyses verified the successful grafting of amine functionalities while maintaining the integrity of the parent framework. CO2 adsorption studies at 0 °C demonstrated that en- and deta-modified MOF-14 exhibited optimal uptake at loadings of 10–15 wt%, achieving a balance between enhanced chemisorption sites and accessible pore volume, whereas the larger bape ligand led to substantial pore obstruction. Additional adsorption measurements at 25 °C confirmed measurable CO2 uptake under conditions closer to practical gas separation processes. Furthermore, evaluation of CO2/N2 separation performance, including IAST calculations for a 15% CO2/85% N2 mixture, revealed substantially enhanced selectivity in the amine-modified frameworks compared to pristine MOF-14. Electrochemical evaluation revealed the excellent energy storage performance of MOF-14 (en) 20%, delivering a high specific capacitance of 972 F g−1, markedly outperforming the pristine material. This study highlights the dual capability of amine-modified MOF-14, presenting efficient low-pressure CO2 capture alongside outstanding promise as an electrode material for high-performance supercapacitors.