Silk-based polyelectrolyte evaporator with excellent salt resistance for high-rate and stable solar desalination

Solar-driven interfacial evaporation technology is a promising solution to solve global freshwater shortages through desalination. However, salt accumulation in the evaporator affects light absorption and reduces evaporation efficiency, thereby significantly reducing the service life and operating efficiency of the evaporator. Herein, we propose a strategy for sustainable salt resistance that enables strong salt resistance and rapid water delivery by in situ polymerization of sodium acrylate (PAAS) on the directional channel. As a result, the as-prepared SF/rGO@PAAS can achieve a high evaporation rate of up to 2.31 kg m⁻² h⁻¹ and high evaporation efficiency of up to 98% under one sun, benefiting from the inherent hydrophilicity of silk fibroin (SF), the directional channel design of water transport layer, and the efficient solar light absorption in full spectrum of reduced graphene oxide (rGO). More importantly, due to the electrostatic effect of PAAS, the evaporator showed excellent salt resistance, with no salt precipitation for 5 days of continuous evaporation in simulated seawater (3.5 wt%) while maintaining the high evaporation rate. This salt resistant evaporator provides an effective solution to the salt accumulation and addresses a key challenge in sustainable desalination.