Supercritical Fluid-Assisted Synthesis of Bimetallic MOFs and Characterization of Their CO₂ Adsorption Performance for Climate Change Mitigation

Abstract

Metal organic framework (MOF) structures are crystalline materials composed of metal ions and organic ligands, known for their large surface area and chemical stability. When synthesized from two metals and a single organic ligand, bimetallic MOF (BMOF) structures are formed, which exhibit significant properties such as high surface area and enhanced chemical and thermal stability due to synergistic effects. In this study, amine-functionalized Ni/Co BMOF structures were synthesized using both conventional solvothermal and supercritical CO₂-assisted methods. The resulting materials were characterized by scanning electron microscopy (SEM) for morphology, X-ray diffraction (XRD) for crystal structure, and BET analysis for surface area and porosity. Additionally, CO₂ adsorption experiments were conducted at 0 °C and 25 °C. The results indicated that BMOF materials synthesized via the supercritical CO₂ method exhibited more uniform morphology, higher crystallinity, and significantly improved textural properties compared to those obtained by the solvothermal method. The BMOF synthesized under supercritical conditions demonstrated a surface area of 885,37 m²/g, a pore volume of 2,02 cm³/g, and a CO₂ adsorption capacity of 6,99 mmol/g at 25 °C, whereas the solvothermally synthesized BMOF exhibited values of 397,62 m²/g, 1,14 cm³/g, and 2,63 mmol/g, respectively. These findings highlight the superior performance of the supercritical synthesis method in enhancing the properties of BMOF structures and demonstrate that BMOFs synthesized via this route serve as effective carbon dioxide adsorbents for climate change mitigation.