## 1 Introduction
Their results indicated that for lower wavelengths (200-900 nm), the extinction coefficient increased for CuO/water nanofluid, while porous foam showed a higher extinction coefficient at higher wavelengths. [PERSON] et al. [8] provided another delightful nanodiamond/EG nanofluid to use in solar collectors. They found a significant increase in the extinction coefficient at the UV region for the tested nanofluid, while above the infrared region, the extinction coefficient was fully dependent on the suspension's base fluid. From the above literature, it was clear that nanoparticles addition dramatically increased the optical performance of nanofluids. Nevertheless, all the above researchers used conventional base fluids such as EG, water, or oil in the nanofluids. Since these traditional coolants' decomposition temperature or thermal stability is very low (<200 \({}^{\circ}\)C), they are not preferred for high-temperature applications. Furthermore, these fluids have many limitations, such as high vapor pressure, less chemical, and thermal stability. As a result, researchers are focused on developing innovative nanofluids with excellent optical and electrical properties that can be used for a different range of applications. In recent years, ionic liquids have sparked substantial attention in their possible application for solar energy processing as they are optically transparent for both UV and visible regions. Ionic liquidsare novel organic salts consisting of anions and cations that exist in the liquid state at room temperature. Meanwhile, the literature suggests that ionic liquids possess fascinating properties such as negligible vapor pressure, high thermal stability, dispersibility, and eco-friendly nature, which are favorable for utilizing it as a base fluid for formulating nanofluids. For instance, [PERSON] et al. [9] investigated the optical properties of ionic liquid-based nanofluids ([HMIM][NTf\({}_{2}\)]/Ni) in DASC. They demonstrated that ionic liquid-based solutions containing nickel-coated carbon nanoparticles obtained a maximum extinction coefficient with less transmittance, making them a promising HTF for solar thermal collectors. In the same way, ion nanofluids were synthesized and improved thermal properties were seen relative to pure ionic liquids. Owing to the fascinating properties of two-dimensional (2D) materials, which are peculiar from three-dimensional (3D) analogs, research on 2D materials increases researchers' attention. 2D MXenes are imperative in applications such as energy storage, energy conversion, lubrication, and batteries due to their significant surface area, making them draw much interest in solar applications. This motivated the present study to analyze the optical property of imidazolium-based ionic liquids dispersed with MXene nanofluid. A comprehensive exploration of nanofluids' significant properties and ionic liquids has been made by [PERSON] et al. [10]. Consequently, with a growing research focus on 2D materials, a form of new materials identical to graphene called MXene has been paid much attention. Usually, it consists of transition metal carbides or nitrides produced by its parent MAX phase's chemical etching. [PERSON] et al. [11] dispersed 1,3-Dimethylimidazolium dimethyl-phosphate ionic liquid with water/MXene nanofluid to improve the efficiency of a hybrid PV/T solar system. Stability and optical property were improved with a maximum thermal efficiency of 13.95%. [PERSON] et al. [12] experimentally investigated the optical, stability, and energy performance of water/MXene nanofluid solar thermal systems. The authors observed an enhancement in the PV/thermal solar systems' optical and thermal efficiency even at low concentrations of MXene. [PERSON] et al. [13] prepared nanofluids containing MXene nanoparticles and ethylene glycol base fluid and analyzed its potential for application as heat transfer fluids. The authors reported a thermal conductivity enhancement of 64.9% without any nanoparticle sedimentation for 30 days.