Strong tough hydrogel solar evaporator with wood skeleton construction enabling ultra‐durable brine desalination

Abstract

Abstract Hydrogels, a highly versatile material platform, are poised to become a promising candidate for interfacial solar evaporators on account of their record‐high evaporation rates. Nevertheless, conventional hydrogels with loose crosslinking, low solid content, and isotropic network structure are plagued by fragile mechanical tolerance, impairing their application in severe seawater environments. Herein, we develop a skeleton‐construct polyelectrolyte hydrogel (SCPH) evaporator by a universal, simple strategy that maintains not only the original properties of hydrogels, but also endows a high mechanical strength. By virtue of this strategy, the SCPH increased its mechanical strength to 1 MPa, 500 times higher than the original hydrogel. Surprisingly, the strategy also endows the SCPH with some extra properties, such as a high salt rejection ratio, a high water‐pumping rate, and low thermal conductivity, which render the SCPH a perfect evaporator. Specifically, this SCPH material significantly improves the long‐term stability of evaporators, enabling the evaporator to be capable of evaporating for 30 days in 20 wt% brine at a stable evaporation rate, exceeding the longest evaporation time ever reported. In addition, it achieves an evaporation rate of up to 2.13 kg m−2 h−1, which is twice that of the currently existing polyelectrolyte hydrogel evaporators. The skeleton construction has the potential to significantly improve the efficiency, stability, and durability of evaporators, hence bringing interfacial desalination technology toward practical applications.

Keywords

• brine desalination
• durability
• mechanical strength
• polyelectrolyte hydrogel
• skeleton construction
• solar evaporator