Latent heat type nanofluid based on MXene and MoS₂ modified hierarchical structured phase change nanocapsules for sustainable and efficient light-heat conversion

Recently, solar energy has garnered widespread attention due to its clean, pollution-free, and renewable characteristics. Among them, latent heat nanofluids (LHNF) are extensively employed in direct absorption solar collectors (DASC) because of their high heat storage density and efficient heat transfer efficiency. In this study, a novel LHNF was prepared through electrostatic interaction between phase change nanocapsules modified with MXene-MoS₂ (hereafter named “n-22@SiO₂-Ti₃C₂T_x-MoS₂ MEPCN”) and ionic liquid, aiming at sustainable light-heat conversion. Phase change nanocapsules are obtained by encapsulating docosane (n-22) within an inorganic SiO₂ shell and modifying it with Ti₃C₂T_x and MoS₂ to improve the absorption of solar energy across the full spectrum. Research indicates that LHNF possesses high thermal stability, low viscosity, and high thermal conductivity. Furthermore, LHNF contains 4 % n-22@SiO₂-Ti₃C₂T_x-MoS₂ can achieve full spectral absorption at an optical path length of 0.005 m. The equilibrium temperature of LHNF-10 % under 1 Sun irradiation can reach 76.3 °C, with a light-heat conversion efficiency of 85.62 %. Its energy storage performance remains relatively stable under cycling conditions. In addition, the water evaporation rate of the fiber fabric coated with LHNF-10 % increased by 94.42 % compared to the untreated fabric, and this increase persisted even after sunlight was turned off. Its outstanding light-heat conversion performance is anticipated to confer application advantage in intermittent solar energy utilization, wearable fabrics, and biomedical materials.