Cu₃BiS₃/MXenes with Excellent Solar–Thermal Conversion for Continuous and Efficient Seawater Desalination

Two-dimensional materials with unique physical and chemical properties have recently attracted widespread attention in the field of solar thermal conversion. However, affected by the Fresnel effect, traditional two-dimensional materials such as MXenes, graphene, transition metal disulfide often have relatively significant light reflection losses at the solid–liquid or gas interface. So how to improve the light absorption of the two-dimensional material performance has become a new challenge in photothermal conversion. Here, we use an improved thermal-injection method to uniformly grow Tricopper(I) Bismuth Sulfide (Cu 3 BiS 3, CBS) on the surface of Ti 3 C 2 nanosheets in a nonaqueous polar solvent environment. A three-dimensional nanoflower-nanosheet structure CBS-Ti 3 C 2 for photothermal conversion has been constructed successfully. Owing to the excellent photothermal performance of Cu 3 BiS 3 in the near-infrared region, the good thermal conductivity of Ti 3 C 2, and the unique porous structure of the composite material, the composite achieves broadband absorption of light (more than 90% in the visible light region, more than 80% in the near-infrared region), which optical model and finite element simulation have theoretically verified. The composite material has obtained higher solar-to-heat conversion performance than similar material systems, and the steady-state temperature can reach 62.3 °C under 1 sun incident light intensity. CBS-Ti 3 C 2 is expected to become a light-absorbing layer material for solar vapor generation devices due to its excellent light-to-heat conversion performance and good material flexibility. It still guarantees a reasonably high steam generation rate (1.32 kg·m –2 ·h –1 ) even with a thinner material thickness (0.48 mg·cm –2 ) and a comprehensive conversion efficiency higher than 90%. Besides, CBS-Ti 3 C 2 also exhibits the characteristics of resisting surface salt accumulation, which is conducive to maintaining the long-lasting photothermal seawater evaporation process. The material’s electronic structure and the charge transfer process of the heterojunction interface have been studied with the first-principles calculation. The high light absorption performance and good thermal conductivity of the composite material are theoretically explained and supported.