Photothermal Membrane of CuS/Polyacrylamide–Carboxymethyl Cellulose for Solar Evaporation

Solar water evaporation is an environment-friendly and clean way of wastewater treatment and seawater desalination. However, a solar evaporator based on a hydrogel substrate still needs excellent toughness to ensure continuous and stable utilization while achieving a fast evaporation rate. In this research, a solar evaporator based on a dual network hydrogel was fabricated by double chemical cross-linking, consisting of polyacrylamide (PAAm), carboxymethyl cellulose (CMC), and CuS. By utilizing N,N′-methylenebisacrylamide (MBA) and Fe3+ for a double chemical cross-linking agent, PAAm and CMC (PAAm–CMC) formed an interpenetrating dual network structure, which is helpful to improve the mechanical properties of a photothermal membrane. The breaking elongation of a CuS/PAAm–CMC membrane is 480%. Meanwhile, the hydrophilic network ensured the high efficiency of water transmission and water activation. The evaporation rate reached 1.613 kg m–2 h–1 at 1 sun, and the photothermal conversion efficiency reached 79%. In the process of a simulated desalination experiment (10 wt % NaCl solution), the evaporation rate did not decrease after 10 cycles, indicating the self-cleaning ability and good durability of CuS/PAAm–CMC.