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-thermal conversion is a key technology in harvesting solar energy for a diverse range of applications including water vapor generation. However, simultaneously ultrafast and highly efficient solar-thermal conversion and scalable fabrication of materials and devices to achieve such performance in practical applications still remain the key unmet challenges. Here we report a hierarchical nanoarchitecture that integrates vertically oriented graphene nanosheets and highly porous graphene aerogel to achieve ultrafast solar-thermal response (a temperature increase of 169.7 C within 1 s), resulting from superior photonic absorption and excellent thermal insulation. Through engineering surface water pathways and minimizing interfacial thermal resistances, ultrafast solar-thermal response (reaching 100 C within 34 s) and simultaneously high energy efficiency (89.4%) for saturated vapor generation at 10 sun is achieved. Importantly, we demonstrate high-throughput, scalable fabrication of the unique nanoarchitecture. Ultrafast medical sterilization is demonstrated as a potential practical application of this green, nanotechnology-enhanced system for large-scale solar energy harvesting.

Oil spills remain a worldwide challenge and need emergency “spill-SOS” actions when they occur. Conventional methods suffer from complex processes and high cost. Here, we demonstrate a solar-heating siphon-capillary oil skimmer (S-SOS) that harvests solar energy, gravitational potential energy, and solid surface energy to enable efficient oil spill recovery in a self-pumping manner. The S-SOS is assembled by an inverted U-shape porous architecture combining solar-heating, siphon, and capillary effects, and works without any external power or manual interventions. Importantly, solid surface energy is used by capillary adsorption to enable the self-starting behavior, gravitational potential energy is utilized by siphon transport to drive the oil flow, and solar energy is harvested by solar-thermal conversion to facilitate the transport speed. In the proof-of-concept work, an all-carbon hierarchical architecture (VG/GF) is fabricated by growing vertically oriented graphene nanosheets (VGs) on a monolith of graphite felt (GF) via a plasma-enhanced method to serve as the U-shape architecture. Consequently, an oil-recovery rate of 35.2 L m–2 h–1 is obtained at ambient condition. When exposed to normal solar irradiation, the oil-recovery rate dramatically increases to 123.3 L m–2 h–1. Meanwhile, the solar-thermal energy efficiency is calculated to be 75.3%. Moreover, the S-SOS system presents excellent stability without obvious performance-degradation over 60 h. The outstanding performance is ascribed to the enhanced siphon action, capillary action, photonic absorption, and interfacial heating in the plasma-made graphene nanostructures. Multiple merits make the current S-SOS design and the VG/GF nanostructures promising for efficient oil recovery and transport of energy stored in chemical bonds.

HIGHLIGHTS• New concept of solar vapour gap membrane distillation (SVGMD) is based on synergizing of nanochannel-guided water transport, localized heating, and membrane separation from feed solution.• First-time introduction of the gap enables long-term stability and non-fouling membrane.• SVGMD exhibits a solar-water energy efficiency higher than state-of-the-art solar vapour systems.ABSTRACT Photothermal membrane distillation (MD) is a promising technology for desalination and water purification. However, solar-thermal conversion suffers from low energy efficiency (a typical solar-water efficiency of ~ 50%), while complex modifications are needed to reduce membrane fouling. Here, we demonstrate a new concept of solar vapour gap membrane distillation (SVGMD) synergistically combining self-guided water transport, localized heating, and separation of membrane from feed solution. A free-standing, multifunctional light absorber based on graphene array is custom-designed to locally heat the thin water layer transporting through graphene nanochannels. The as-generated vapour passes through a gap and condenses, while salt/contaminants are rejected before reaching the membrane. The high solar-water efficiency (73.4% at 1 sun), clean water collection ratio (82.3%), excellent anti-fouling performance, and stable permeate flux in continuous operation over 72 h are simultaneously achieved. Meanwhile, SVGMD inherits the advantage of MD in microorganism removal and water collection, enabling the solar-water efficiency 3.5 times higher compared to state-of-the-art solar vapour systems. A scaled system to treat oil/seawater mixtures under natural sunlight is developed with a purified water yield of 92.8 kg m −2 day −1 .Our results can be applied for diverse mixed-phase feeds, leading to the next-generation solar-driven MD technology.

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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.

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The properties of concrete were studied when the proportions of 37.5 and 19.5 mm stone in the coarse aggregate were varied. With the cement content of 160 kg/m3 and the ratio of water/cement (w/c) greater than 0.9, the compressive strength is maximum at 25 percent by weight (w/o) of 37.5 mm stone. Conversely, for the cement content of 350 kg/m3 and w/c ratios of less than 0.50, maximum compressive strength is substantively reduced. For both 160 kg/m3 and 350 kg/m3 cement contents, workability improves slightly as the proportion of the 37.5 mm stone is increased. For 100 mm fixed slumps and cement content of less than 160 kg/m3, there was little change in compressive strength as the proportion of 37.5 mm stone increased. However, when cement content was increased from 190 to 350 kg/m3, maximum compressive strength was observed, which shifted downward from 50 w/o to 25 w/o of 37.5 mm stone. In general, to maintain a 100 mm slump, water demand decreased as the proportion of 37.5 mm stone in the coarse aggregate fraction increased.Key words: concrete, compressive strength, workability, slump, aggregate, size, cement.