# Ionic Liquids Hybridization for Carbon Dioxide Capture: A Review
## 4 Application of ILs Hybrid Material in Carbon Dioxide
### ILs/Mof  
Metal-organic framework (MOF) first came to light on 1995 in an effort to find a new porous solid material that exhibits zeolite-like properties, namely, stability, microporosity, guest exchange and selective catalytic activity [100]. This new class of porous material has a highly-ordered crystalline structure, large surface area and tunable pore size, making it suitable for various applications, such as catalysis, wastewater treatment, and drug delivery [101; 102; 103]. In the meantime, MOFs can be designed to selectively adsorb CO\({}_{2}\) by adjusting their pore size and chemical functionality. For example, MIL-53, ZIF-8, HKUST-1, MOF-74 and Uio-66 are some of the commonly used MOFs for CO\({}_{2}\) capture [104; 105; 106; 107; 108]. Magnesium (Mg)-MOF-74 was first synthesized by [PERSON] and co-workers via solvothermal method and has since become the current benchmark due to its exceptional CO\({}_{2}\) adsorption capacity, which is 8.8-9.0 mmol/g at ambient condition [10]. The remarkable performance of Mg-MOF-74 is due to its high surface area, 1495 m\({}^{2}\)/g, which is the highest among the MOF-74 group. Additional work that was performed on different metal salts including Zinc (Zn), Nickel (Ni) and Cobalt (Co) towards CO\({}_{2}\) capture has indicated that Mg-MOF-74 recorded the highest adsorption capacity, 23.6 wt% and 35.2 wt% at 0.1 and 1.0 atm, respectively. However, despite demonstrating remarkable performance, MOFs are susceptible to degradation, particularly after exposure to moisture. Therefore, addressing this weakness has become one of the main challenges, as CO\({}_{2}\) does contain moisture which, in turn, will negatively impact the MOF performance. The incorporation of IL into MOF to produce hybrid porous material is a new approach in producing a new adsorbent with good stability, high CO\({}_{2}\) affinity and selectivity. In 2011, [PERSON] et al. conducted a computational study on the incorporation of [BMIM][PF\({}_{6}\)] into IRMOF-1 for CO\({}_{2}\)/N\({}_{2}\) selectivity by using molecular dynamic (MD) and Monte Carlo (MC) simulation [37]. The calculation on radial distribution function (RDF) revealed the structure of [BMIM][PF\({}_{6}\)] is in ordered due to confinement effect of IRMOF-1. Besides that, as the bulky chain of [BMIM]\({}^{+}\) preferentially resides on the open pore of IRMOF-1, the smaller [PF\({}_{6}\)]\({}^{-}\) anion had formed a strong interaction with the framework, thus residing in the metal cluster corner. In the meantime, the study on CO\({}_{2}\) capture by IRMOF-1/[BMIM][PF\({}_{6}\)] was simulated by mimicking flue gas consisting of a 15:85 CO\({}_{2}\)/N\({}_{2}\) mixture. According to structure analysis, CO\({}_{2}\) is attracted to the sites of metal cluster of pristine MOF. The presence of [BMIM][PF\({}_{6}\)] resulted in higher CO\({}_{2}\) adsorption capacity compared to N\({}_{2}\). This is due to the strong affinity between CO\({}_{2}\) and [PF\({}_{6}\)]\({}^{-}\). Meanwhile, increasing the weight ratio of IL incorporating into IRMOF-1 indicates an increase in CO\({}_{2}\) selectivity that was caused by the additional presence of a favorable site, which is [PF\({}_{6}\)]\({}^{-}\). Analysis on a CO\({}_{2}\) isotherm for pristine IRMOF-1 and IRMOF-1/[BMIM][PF\({}_{6}\)] showed that, the hybrid material has a better CO\({}_{2}\) capacity at low pressure owing to the presence of narrow constrained pores resulting from IL addition. In other works, [PERSON] and co-workers combined both simulation and experimental works in order to gain a better understanding on the types of force field that possibly influence the CO\({}_{2}\) capture [109]. The grand conical MC (GCMC) simulation was used to demonstrate two generic force fields, Universal Force Field (UFF) and Dreiding, in order to achieve better prediction performance of nine Cu-BTC/IL materials toward CO\({}_{2}\), CH\({}_{4}\) and N\({}_{2}\) adsorption.