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 utilizingrenewable solar energy. However, the engineering of efficient photothermalmaterial is a significant obstacle. In the present study, a carbon foam is synthe-sized from the upcycling of waste PET and hydrothermally functionalized with aheterostructure composed of Cu3 SbS4 and Sb2 S3 . Material characterizationsdemonstrated the successful decoration of nanochannels on graphitic carbonfoam (CF). The analysis of the optical properties in the UV/Vis-NIR spectralrange demonstrated excellent absorption properties of 96% for Cu 3 SbS4 -Sb2 S3 /CF compared to Sb2 S3 /CF (48%) and CF (68%) in near-IR. Photothermaldesalination results reveal the evaporation rate of 2.82 kg m−2 h−1 forCu3 SbS4 -Sb2 S3 /CF compared to 1.4 kg m−2 h−1 for Sb2 S3 /CF and 1.58kg m−2 h−1 for CF, with 99% salt removal in condensed water. Theformation of the composite leads to a high surface temperature and enhancedevaporation rate. The contact angle analysis confirmed the hydrophilicnature of the material that plays a crucial role in the solar desalinationprocess. These findings elucidate the effective photothermal performanceachieved through chalcogenide heterostructure engineering supportedon upcycled carbon foam derived from waste PET, demonstrating a practicalapplication aligned with circular economy principles in solar desalination.