Spider-cavity structured Ag/PDA@NiCuO/CF evaporator with bilateral siphon-driven channels for enhanced solar desalination

Amid burgeoning population growth and rapid industrialization, freshwater resources are under mounting pressure. This study introduces a novel interfacial evaporator employing a biomimetic spider-cavity structure composed of Ag nanoparticle-decorated polydopamine-coated CuO x /NiO composite on copper foam (Ag/PDA@NiCuO/CF). This design integrates hierarchical micro-nano architectures that maximize light absorption (91 %) and enhance localized photothermal conversion. Bilateral siphon-driven channels independently manage seawater supply and brine drainage, effectively preventing salt accumulation on the photothermal surface. Experimental results demonstrate that the proposed evaporator, under one sun illumination, achieves an evaporation rate of 1.50 kg m −2  h −1 and a solar-to-steam conversion efficiency of 96.7 %. It maintains stable evaporation performance under high salinity (20 wt% NaCl) and shows no salt deposition after 10 h of continuous evaporation, exhibiting excellent anti-salt deposition capability. Practical outdoor tests further validate its reliability, with stable operation and an average evaporation rate of ∼1.58 kg m −2  h −1 over 9 h. Ion concentration and electrical resistance tests confirm its high desalination efficiency, meeting the drinking water standards set by the WHO. Overall, this spider-cavity structured evaporator represents an innovative solution to address solar desalination challenges, particularly in salt management and stable, high-efficiency water purification.