Hofmeister Effect-Assisted Facile Fabrication of Self-Assembled Poly(Vinyl Alcohol)/Graphite Composite Sponge-Like Hydrogel for Solar Steam Generation

Abstract

The use of hydrogel-based interfacial solar evaporators for desalination is a green, sustainable, and extremely concerned freshwater acquisition strategy. However, developing evaporators that are easy to manufacture, cheap, and have excellent porous structures still remains a considerable challenge. This work proposes a novel strategy for preparing a self-assembling sponge-like poly(vinyl alcohol)/graphite composite hydrogel based on the Hofmeister effect for the first time. The sponge-like hydrogel interfacial solar evaporator (PGCNG) is successfully obtained after combining with graphite. The whole process is environmental-friendly and of low-carbon free of freezing process. The PGCNG can be conventionally dried and stored. PGCNG shows impressive water storage performance and water transmission capacity, excellent steam generation performance and salt resistance. PGCNG has a high evaporation rate of 3.5 kg m⁻² h⁻¹ under 1 kW m⁻² h⁻¹ solar irradiation and PGCNG demonstrates stable evaporation performance over both 10 h of continuous brine evaporation and 30 cycles of brine evaporation. Its excellent performance and simple, scalable preparation strategy make it a valuable material for practical interface solar seawater desalination devices.