Abstract: The study of solar interfacial evaporation of composite photovoltaic materials is becoming a hot research topic, and the design of a low-cost, flexible product with high solar energy utilisation has become the key to the research. In this paper, a carbon-based material with high specific surface area, strong light absorption, good hydrophilicity, and enhanced water transport was prepared using waste polyester (PET). The evaporation film made with this material not only has a high evaporation rate of 2.63 kg·m⁻²·h⁻¹, but also has the ability to work persistently and stably. More importantly, the material not only showed little change in evaporation rate in a 3.5 wt% NaCl solution, but also maintained an evaporation rate above 2.00 kg·m⁻²·h⁻¹ in the presence of heavy metal ions. In addition, the outdoor evaporation experiments showed that its one-day fresh water yield reached 4.78 kg/m⁻²/day, and the concentration of methylene blue in the water before and after evaporation decreased by 99.2%, which provides the possibility of desalination of polluted water in the future. This work provides a new direction for the resourceful use of waste plastics and the use of clean energy, and opens up new ideas for desalination.