Hybrid Hydrogel Evaporators Integrated with the BiOI/Bi ₂ S ₃ Heterojunctions for Enhanced Solar Desalination and Photocatalytic Reduction

Solar-driven water purification is a key strategy for freshwater production. In this study, BiOI/Bi₂S₃ poly(vinyl alcohol) hydrogel (BPH) that integrates photothermal and photocatalytic effects for synergistic desalination and heavy metal ion removal is reported. The hybrid hydrogel serves as an efficient platform for steam generation and Cr (VI) reduction due to its dynamic hydrophilic network. Furthermore, the incorporation of Bi₂S₃ significantly enhances the NIR absorption capability of the heterojunction photocatalyst, thereby boosting its photothermal efficiency. The results indicate that BPH exhibits comprehensive water purification capabilities by optimizing material selection and design. BPH achieves an evaporation rate of 2.34 kg m^-2 h^-1 while its optimal reduction efficiency for the probe pollutant Cr (VI) reaches 100% within 30 min under a solar irradiation of 1 kW m^-2. This work presents a novel perspective for designing seawater purification systems capable of removing heavy metal ions.