Upcycled PET‐Derived Carbon Foam Functionalized with Cu3SbS4–Sb2S3 Heterostructures for Efficient Interfacial Solar Desalination

Solar desalination is an emerging technique to produce fresh water utilizing renewable solar energy. However, the engineering of efficient photothermal material is a significant obstacle. In the present study, a carbon foam is synthesized from the upcycling of waste PET and hydrothermally functionalized with a heterostructure composed of Cu3SbS4 and Sb2S3. Material characterizations demonstrated the successful decoration of nanochannels on graphitic carbon foam (CF). The analysis of the optical properties in the UV/Vis-NIR spectral range demonstrated excellent absorption properties of 96% for Cu3SbS4-Sb2S3/CF compared to Sb2S3/CF (48%) and CF (68%) in near-IR. Photothermal desalination results reveal the evaporation rate of 2.82 kg m−2 h−1 for Cu3SbS4-Sb2S3/CF compared to 1.4 kg m−2 h−1 for Sb2S3/CF and 1.58 kg m−2 h−1 for CF, with 99% salt removal in condensed water. The formation of the composite leads to a high surface temperature and enhanced evaporation rate. The contact angle analysis confirmed the hydrophilic nature of the material that plays a crucial role in the solar desalination process. These findings elucidate the effective photothermal performance achieved through chalcogenide heterostructure engineering supported on upcycled carbon foam derived from waste PET, demonstrating a practical application aligned with circular economy principles in solar desalination.