Reed Leaves Inspired Silica Nanofibrous Aerogels with Parallel-Arranged Vessels for Salt-Resistant Solar Desalination

Abstract

Sufficient and clean freshwater is still out of reach for billions of people around the world. Solar desalination from brine is regarded as one of the most promising proposals to solve this severe crisis. However, most of the reported evaporators to date still suffer from the decreasing evaporation rate caused by salt crystallization accumulated on their surface. Here, inspired by the vascular tissue structure, transpiration, and antifouling function of reed leaves, we design biomimetic hierarchical nanofibrous aerogels with parallel-arranged vessels and hydrophobic surfaces for highly efficient and salt-resistant solar desalination. Foldable vessel walls and flexible silica nanofibers give the reed leaf-inspired nanofiber aerogels (R-NFAs) excellent mechanical properties and enable them to withstand repeated compression. Besides, the R-NFAs can efficiently absorb sunlight (light absorption efficiency: 94.8%) and evaporate the brine to vapor, similar to reed leaves (evaporation rate: 1.25 kg m −2 h −1 under 1 sun). More importantly, enabled by the hydrophobic surfaces and parallel-arranged vessels, the R-NFAs can work stably in high-concentration brine (saturated, 26.3 wt %) under high-intensity light (up to 6 sun), demonstrating potent salt resistance. It is expected that R-NFAs with combined antisalt pore and surface structures will provide a designed concept for salt-resistant solar desalination.

Sunflower-Stalk-Based Solar-Driven Evaporator with a Confined 2D Water Channel and an Enclosed Thermal-Insulating Cellular Structure for Stable and Efficient Steam Generation

“…Moreover, since the ISSG devices need to work under wet or high-humidity conditions, it is essential to evaluate the thermal insulation performance of ISSG devices in the wet state. For ISSG devices with an interconnected porous structure, their thermal conductivities are obviously increased in the wet state − and close to that of pure water . This is attributed to the fact that the air in the open pores is replaced with water.…”

Fibrous Aerogels for Solar Vapor Generation

“…The SiO 2 nanofiber aerogel was constructed by homogenizing of nanofiber membrane to obtain dispersion and then freeze-drying. With an inspiration of reed leaves, the above SiO 2 fibrous aerogel with parallel-arranged vasculature was chosen as substrate and polypyrrole or CNTs deposited on the substrate as solar absorber ( Figure 5A ; Dong et al, 2020 ; Dong et al, 2021 ). The salt resistance of aerogel is outstanding, which could work stably in high concentration brine.…”

A Stable Bilayer Polypyrrole‐Sorghum Straw Evaporator for Efficient Solar Steam Generation and Desalination

“…[ 16–31 ] For example, Dong et al. [ 32 ] developed reed leaves inspired silica nanofibrous aerogel interfacial evaporator that achieves an evaporation rate of 1.25 kg m −2 h −1 under 1 Sun. You et al.…”

“…[11,15] However, seawater has a remarkably weak absorption rate of sunlight, resulting in wasting the majority of the energy and a low evaporation efficiency.In recent years, researchers have developed a solar interfacial evaporator, which can effectively improve the evaporation efficiency of solar evaporators compared to the traditional technology that uses solar energy to directly heat a large amount of water. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] For example, Dong et al [32] developed reed leaves inspired silica nanofibrous aerogel interfacial evaporator that achieves an evaporation rate of 1.25 kg m −2 h −1 under 1 Sun. You et al [33] developed a cellulose aerogel from natural wood to act as a solar interfacial evaporator, which can achieve an evaporation rate of 1.40 kg m −2 h −1 , corresponding to an evaporation efficiency of 83.4% under 1 Sun.…”