Copper sulfide integrated functional cellulose hydrogel for efficient solar water purification

Hydrogels are emerging materials for solar steam generation to alleviate water scarcity. Herein, a semiconductor of copper sulfide (CuS) was integrated into cellulose hydrogel to fabricate a solar steam evaporator. Sustainable and low-cost cotton linter (cellulose) was regenerated by NaOH/urea solvent. Epichlorohydrin was added as a cross-linking agent to enhance the mechanical robustness of the composite hydrogel, and CuS crystals were tightly attached to cellulose fibers and uniformly distributed in the hydrogel matrix. Under simulated solar light, a heating zone was established at the top surface of the composite hydrogel, and CuS can efficiently absorb and convert light into heat. The hydrophilic cellulose network affords an adequate water supply and a low water vaporization enthalpy. By tuning the CuS loadings, the optimized evaporation rate and solar-to-vapor efficiency could reach 2.2 kg/m2/h and 87 %, respectively, under 1 sun irradiation. The evaporation rate remained above 2.1 kg/m2/h after 48 h of irradiation. Moreover, the hydrogels (with a CuS loading of 30 wt%) showed a effi-ciently photocatalytic degradation of 95 % for methylene blue and 92 % for Rhodamine B. Such functional hydrogel evaporator holds great potential for practical water treatment and solar-driven applications.

Automated summary

In this study, a solar steam evaporator was fabricated by integrating copper sulfide semiconductor into cellulose hydrogel, which shows great potential for addressing water scarcity. The regenerated cellulose hydrogel with low-cost cotton linter and cross-linking agent exhibits mechanical robustness, while the attached CuS crystals efficiently absorb and convert light into heat. With optimized CuS loadings, the evaporator achieves a high evaporation rate of 2.2 kg/m2/h and solar-to-vapor efficiency of 87% under 1 sun irradiation. Furthermore, the hydrogel with CuS loading also demonstrates efficient photocatalytic degradation of organic dyes. This functional hydrogel evaporator holds promise for water treatment and solar-driven applications.