Carbon–MoS₂ Composite Loaded in Poly(vinyl alcohol)–Chitosan Aerogel as Dual-Functional Photothermal Material for Efficient Water Evaporation and Thermal Storage under Solar Irradiation

Interfacial solar-driven evaporation is considered an effective desalination technology to produce freshwater. However, salt accumulation severely slows or even stops water evaporation. In this study, a composite of porous carbon and MoS2 was loaded into a porous aerogel of poly(vinyl alcohol) (PVA)–chitosan (CS) by directed freezing to produce stable and salt-resistant interfacial evaporators. The obtained PVA–CS–C0.2–MoS2 composite aerogel (PC–C0.2M) exhibited excellent evaporation performance through the dual network structure of PC, which greatly facilitated water transport. In addition, the highly efficient absorbance (97.42%) of the porous carbon composite molybdenum disulfide (C0.2MoS2) also contributes to the efficient light-absorbing properties of PC–C0.2M. Thanks to its oriented porous structure, high light absorbance, and good wettability, PC–C0.2M achieved a water evaporation rate of 2.62 kg m–2 h–1 at 1 kW m–2 and a photothermal conversion efficiency of 92.14%. It also displayed outstanding salt resistance and can purify simulated seawater and dye-contaminated water. As a functional material capable of being used in multiple applications, aerogel material also serves as a support for loaded phase change materials through capillary forces and pore confinement. The excellent structure of PC–C0.2M provided a favorable carrier for the encapsulation of phase change materials (PCMs), which resulted in the enthalpy of melting and solidification of the PC–C0.2M composite paraffin wax (PW) PCM reaching 197.16 J g–1 and 206.42 J g–1, respectively. Furthermore, by combining aerogel with PCM, the evaporation rate of PC–C0.2M-co-PCM in a dark environment is 0.60 kg m–2 h–1, which is 2.22 times that of PC, enabling its excellent evaporation performance even at night. In summary, by exploiting PCMs to achieve rational utilization of solar thermal energy, the innovative integration of PCMs and photothermal materials in interface evaporation system provides a promising solution for evaporators to simultaneously achieve efficient energy storage and seawater desalination under intermittent solar radiation.