Multifunctional Solar Waterways: Plasma‐Enabled Self‐Cleaning Nanoarchitectures for Energy‐Efficient Desalination

Abstract

Evaporating seawater and separating salt from water is one of the most promising solutions for global water scarcity. State‐of‐the‐art water desalination devices combining solar harvesting and heat localization for evaporation using nanomaterials still suffer from several issues in energy efficiency, long‐term performance, salt fouling, light blocking, and clean water collection in real‐world applications. To address these issues, this work devises plasma‐enabled multifunctional all‐carbon nanoarchitectures with on‐surface waterways formed by nitrogen‐doped hydrophilic graphene nanopetals (N‐fGPs) seamlessly integrated onto the external surface of hydrophobic self‐assembled graphene foam (sGF). The N‐fGPs simultaneously transport water and salt ions, absorb sunlight, serve as evaporation surfaces, then capture the salts, followed by self‐cleaning. The sGF ensures effective thermal insulation and enhanced heat localization, contributing to high solar‐vapor efficiency of 88.6 ± 2.1%. Seamless connection between N‐fGPs and sGF and self‐cleaning of N‐fGP structures by redissolution of the captured salts in the waterways lead to long‐term stability over 240 h of continuous operation in real seawater without performance degradation, and a high daily evaporation yield of 15.76 kg m−2. By eliminating sunlight blocking and guiding condensed vapor, a high clean water collection ratio of 83.5% is achieved. The multiple functionalities make the current nanoarchitectures promising as multipurpose advanced energy materials.

Designing a bioinspired synthetic tree by unidirectional freezing for simultaneous solar steam generation and salt collection

“…In this practical device, water productivity is low because of the limited water condensation process. The device can be further optimized with mechanical moving parts to enhance water productivity and salt crystals 16 …”

“…The device can be further optimized with mechanical moving parts to enhance water productivity and salt crystals. 16…”

“…Various absorbers, such as carbon‐based materials, conjugated polymers, semiconductors, and plasmonic nanomaterials, have been designed to float on the surface of water 2,12–15 . However, to reduce heat loss in the form of heat conduction to bulk water, water is usually transported to the evaporation surface via capillary channels, where salt accumulation easily occurs 16–20 . The accumulated salt can severely reduce the adsorption efficiency, clog the water path, and decrease the evaporation area.…”

“…2,[12][13][14][15] However, to reduce heat loss in the form of heat conduction to bulk water, water is usually transported to the evaporation surface via capillary channels, where salt accumulation easily occurs. [16][17][18][19][20] The accumulated salt can severely reduce the adsorption efficiency, clog the water path, and decrease the evaporation area. As a result, solar steam generation process will be stopped without a sufficient water supply.…”

Carbonized Tree‐Like Furry Magnolia Fruit‐Based Evaporator Replicating the Feat of Plant Transpiration

“…Note that, with the rapid growth of vapor generation rate, the collection of condensate has been the Achilles's heel of solar distillation (Figure S22, Supporting Information). It is reported that reducing the pressure of evaporation chamber or separating the evaporation chamber and condensation chamber in space favor high efficient vapor collection.…”