A novel and expedient design of high-efficiency solar-driven interface evaporator fabricated on polyurethane sponge

Abstract

Based on the background of freshwater scarcity, desalination technology has been widely applied, and solar interface evaporator is a highly promising strategy for seawater desalination. However, its limited stability and low efficiency have restricted the practical implementation of interfacial evaporation. In this paper, we propose an improved solar evaporator, in which a polyurethane sponge is used as a substrate, and a photo-thermal conversion coating is formed on the sponge through a reaction between iron ions and the abundant polyphenolic materials in tea leaves. The polyurethane sponge, modified by polyphenolic materials. and iron ions, exhibits high hydrophilicity and ensures the efficient transport of water within the evaporator due to its high porosity and permeability. Moreover, the polyphenolic materials, serving as a chelating agent, reacts with iron ions with moderate photo-thermal conversion properties, resulting in a dark photo-thermal conversion coating on the sponge, ensuring efficient photo-thermal conversion throughout the entire evaporator.