3D printed long-durable salt-resistant solar evaporator for indirect efficient seawater electrolysis

The carbon emissions are becoming increasingly severe. Hydrogen, as a high-quality carbon-free energy, requires extremely high reliance on freshwater resources. Interfacial solar evaporation holds great promise for low-carbon, high-efficiency seawater desalination. However, the pore blockage and photothermal performance degradation caused by the enrichment of salt ions while resisting salt evaporation remains a challenging scientific bottleneck, which restricts its widespread applications. Herein, we manufacture a salt-resistant hydrogel evaporator with unique microstructured surface via 3D printing technology. The surface temperature of the hydrogel evaporator increased by 14.6 °C within 40 min (solar irradiation: 1000 W m⁻²), achieves remarkable solar evaporation capability (2.35 kg m⁻² h⁻¹, 92.1%). More importantly, the evaporator exhibits excellent evaporation efficiency under varying salinities. Furthermore, the efficient utilization of freshwater obtained by the solar evaporation to produce H₂ in the daytime and salt release at night, achieves an average hydrogen production rate of 3.55 L m⁻² h⁻¹ within one week and an average evaporation rate of 2.14 kg m⁻² h⁻¹ within two weeks after salt release. This work achieves sustainable utilization of low-carbon devices, and provides new ideas for all-weather resource utilization systems in the fields of freshwater and low-carbon H₂ production.