Bismuth oxychloride-sodium alginate hydrogel derived interface desalination solar evaporator for environmental remediation

[Display omitted] •The multifunctional floating layer is constructed by co-sedimentation method.•Polyurethane sponge was used as a hydrogel growth template.•Bismuth oxychloride has the photothermal conversion and photodegradation properties. In order to solve the pollution faced by traditional evaporators, an interface evaporator containing a floating unit and a bismuth oxychloride composite hydrogel unit was constructed. The innovation lies in: 1. The infiltrating behavior of the floating unit is non-wetting; 2. The water contact angle of the floating layer is 160° and the construction strategy can be extended to sponges, fabrics and felts. The obtained bismuth oxychloride composite hydrogel retained an excellent water supply and salt suppression capacity, with the water droplets expanding within 120 ms and reaching a steam production rate of 1.82 kg·m−2·h−1. From band structure calculation, the conduction and valence band are −0.928 eV and 1.502 eV, respectively. Comparative experiments and ESR analyses demonstrated the h+ degraded species. It is hoped that the construction of the above interface evaporator could bring a new solution for environmental restoration.