Solar-powered water desalination has been considered as one of the most promising solutions to alleviate clean water scarcity. In concentrated brine, the strong hydration ability of ions increases the required energy for water evaporation and thus lowers the desalination performances of most-existing solar vapor generators (SVGs). Here, a novel SVG is reported that exhibits superior desalination performance in brine than in pure water. This SVG is constructed by the complexation of oppositely charged polyelectrolytes into a hierarchically porous hydrogel (HPH), with interpenetrated polyaniline as efficient light absorbers. With controlled thermal management, the evaporation rate of this HPH-based SVG is 2.79 kg m⁻² h⁻¹ in simulated brine (3.5 wt% NaCl solutions) under one sun illumination, 67% higher than that in pure water (1.67 kg m⁻² h⁻¹) and more prominent than existing salt-resistant SVGs. Desalination tests with real seawater indicate that HPH is salt-resistant and sustainable for fast freshwater production. All-atom molecular dynamics simulations indicate that the unique interactions between the oppositely charged groups of the polyion complex and the mobile ions in brine can alter the water state, resulting in enhanced hydrability of the polymeric skeleton. This work provides a new approach for the development of next-generation SVGs with enhanced solar desalination performance.

There has been increasing interest in the emerging ionic thermoelectric materials with huge ionic thermopower. However, it’s challenging to selectively tune the thermopower of all-solid-state polymer materials because the transportation of ions in all-solid-state polymers is much more complex than those of liquid-dominated gels. Herein, this work provides all-solid-state polymer materials with a wide tunable thermopower range (+20~−6 mV K⁻¹), which is different from previously reported gels. Moreover, the mechanism of p-n conversion in all-solid-state ionic thermoelectric polymer material at the atomic scale was presented based on the analysis of Eastman entropy changes by molecular dynamics simulation, which provides a general strategy for tuning ionic thermopower and is beneficial to understand the fundamental mechanism of the p-n conversion. Furthermore, a self-powered ionic thermoelectric thermal sensor fabricated by the developed p- and n-type polymers demonstrated high sensitivity and durability, extending the application of ionic thermoelectric materials.

Our reliable and reproducible cross-linking procedure ranges from careful equilibration of the liquid polymer precursor to calculating the thermo-mechanical properties of the cross-linked polymer. Our approach can be used to cure not only pure thermoset polymers, but also thermoset-based composite materials.