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.
Solar desalination that exploits interfacial evaporation represents a promising solution to global water scarcity. Real-world feedstocks (e.g., natural seawater and contaminated water) include oil contamination issues, raising a compelling need for desalination systems that offer anti-oil-fouling capability; however, it is still challenging to prepare oil-repellent and meanwhile water-attracting surfaces. This work demonstrates a concept of molecularly dispersing functional F and Na sites on plasma-made vertically oriented graphene nanosheets to achieve an in-air and in-water oleophobic, hydrophilic surface. The graphene architecture presents high in-air (138°) and in-water (145°) oil contact angles, with simultaneously high water affinity (0°). Such surface wettability is enabled by oleophobic, hydrophobic −CF x , and hydrophilic −COONa groups of the molecules that disperse on graphene surfaces; low-dispersion (0.439 mJ m −2 ) and high-polarity (95.199 mJ m −2 ) components of the solid surface tension; and increased surface roughness produced by graphene edges. The graphene nanostructures pump water upward by capillary action but repel oil from the surface, leading to complete in-water and in-air oil rejection and universal anti-oil-fouling capability for solar desalination. Consequently, stable solar−vapor energy efficiency of more than 85% is achieved regardless of whether the feedstock is pure or oil-contaminated water (e.g., a mixture of oil floating on water, an oil-in-water emulsion), resulting in the efficient production of clean water over several days. This outstanding performance is attributed to the universal (both in-water and in-air) oleophobic wettability, together with high light absorptance contributed by nanotraps, fast interfacial heat transfer enhanced by finlike nanostructures, and accelerated evaporation enabled by sharp graphene edges.
Supercapacitors have been considered as a promising alternative of aluminum electrolytic capacitors (AECs) for AC line filtering applications. However, realizing supercapacitors with fast frequency response and superior energy density still remains an open issue. Herein, we demonstrate a hierarchical, vertically‐oriented carbon nanowall foam (CWF) supercapacitor using mixed room temperature ionic liquids (RTILs) for high‐performance AC line filtering. Hierarchical CWF exhibits macrospores as electrolyte reservoirs to shorten ion transport distance, vertically‐oriented, open channels to enable fast ion diffusion and consecutive scaffolds to promote electron transfer. CWF supercapacitor using RTIL mixture realizes a recorded‐high areal energy density of 1.23 μWh cm−2 at 120 Hz (almost ∼2.0 times/∼10.0 times larger than those of organic/aqueous electrolytes, respectively) and fast frequency response (RC time constant=∼1.3 ms). More importantly, CWF supercapacitor achieves a capacitance advantage over commercial AECs up to 1,000 V, substantially larger than those reported in state‐of‐the‐art literatures (maximum of ∼250 V).
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