The role of carbon nanotubes and graphene oxide on the performance of metal-organic frameworks for CO₂ capture

To address climate change, it is essential to decrease the release of CO₂ from burning fossil fuels. Synthesis of nickel-based MOFs (MOF-74) is a kind of technology that may effectively capture CO₂ from flue gas. However, their practical use is hindered by their instability and limited ability to adsorb CO₂. In this work, MOFs with carbon nanotubes (CNTs) and graphene oxide (GO) were synthesized using solvothermal techniques, yielding MOF/CNTs and MOF/GO. The XRD, FTIR, TGA, DSC, FESEM, and BET analyses were used to assess their performance. The sorption capacities of CO₂ and CH₄ at 25 °C, as well as the selectivity of IAST, were evaluated. The XRD and FTIR were used to confirm the synthesis. The thermal stability of MOF/CNTs was found to be 20 °C higher than that of pure MOF. The contact angle results suggested that the inclusion of CNTs increased the hydrophobicity of MOF/CNTs. The BET results indicated that the surface areas of MOF/CNTs and MOF/GO were decreased. The adsorption capacity of MOF/GO was found to be much lower than that of pure MOF, with a reduction of 22 % CO₂. It was noted that MOF showed the highest IAST selectivity value, which was 41.05. According to the hard-soft acid-base (HSAB) hypothesis, Grand Canonical Monte Carlo (GCMC) simulations showed that MOFs have electronic properties similar to CO₂ molecules with good selectivity.