Synthesis of MOF-MXene-supported MgSO4 composites for efficient thermochemical heat storage

Abstract

Magnesium sulfate heptahydrate (MgSO₄•7H₂O) has emerged as a highly promising candidate for thermochemical heat storage applications. However, it encounters stability challenges during hydration/dehydration cycles and demonstrates inadequate reaction kinetics under equilibrium conditions. Metal-organic frameworks (MOFs) have recently attracted significant attention due to their large surface area and well-ordered porous structure, while two-dimensional MXene materials have gained prominence in the materials field due to their exceptional thermal conductivity. The integration of these materials with active salt hydrates to develop novel thermal storage composites is hypothesized to present significant potential for space heating applications. In this study, a novel thermochemical heat storage material, NH₂-MIL-B88(Fe)-MXene-supported MgSO₄ (Fe-MOF-MXene-MgSO₄), was synthesized through impregnation methodology. TG-DSC analysis indicated that Fe-MOF-MXene-MgSO₄ demonstrated an enhanced hydration enthalpy of 1503 J g⁻¹ compared to pure MgSO₄•7H₂O (1180 J g⁻¹). The composite demonstrated superior cycling stability with only 2.08 % capacity loss compared to 24.27 % for pure MgSO₄•7H₂O over 20 consecutive cycles. This performance enhancement can be attributed to the synergistic effects of Fe-MOF and MXene components, which collectively improve the structural integrity and dispersion of MgSO₄•7H₂O. The synthesized Fe-MOF-MXene-MgSO₄ composite exhibits significant potential for advanced thermochemical heat storage applications.