Superwetting Monolithic Hollow‐Carbon‐Nanotubes Aerogels with Hierarchically Nanoporous Structure for Efficient Solar Steam Generation

Abstract

hydrogen, [2] solar power plants, [3] photovoltaic cells, [4] photocatalysis, [5] and water desalination, [6] the photothermal materials based solar water evaporation is one of the most promising approaches for harvesting and conversion of solar energy. Solar vapor generation, more specifically, is a surface water evaporation process in which the light is absorbed and converted to heat energy by photothermal materials to generate vapor. Compared with the common water evaporation by solar radiation as heat source which suffers from the drawback of low solar energy conversion efficiency due to the fact that the part solar energy is converted to heat bulk water or is lost to the external environment, solar vapor generation based on photothermal materials has great advantages for its high light-to-heat conversion efficiency due to the fact that solar radiation is only harvested and located at the water-air interface to heat thin air-water surface layer that can effectively minimize the heat loss. [7] Based on the merits mentioned above, up to now, the solar steam generator has been emerged as a kind of efficient device for harvesting solar energy and attracted extensively much more attention in both industrial and academic research throughout the past decades. [8,9] In a given solar steam generation system, the photothermal materials is essential. A desired photothermal material should meet the following criteria: the broadband sunlight absorbability, low thermal conductivity, open porosity for rapid water molecules transportation, and high-energy conversion efficiency. [10,11] Understanding of these complementary roles of these parameters for photothermal material, so far, a number of photothermal materials, including carbon-based materials, [7,8,[12][13][14] metallic nanoparticles, [15][16][17] biomass-based materials, [18,19] and porous polymers, [20,21] etc., have been developed to use as efficient solar steam generators.In general, porous materials with bilayer structure are widely adapted as solar steam generator, in which the top layer consists of carbon materials for light absorption (e.g., graphene, [13] CNTs, [14] graphite, [7] etc.) while the bottom layer is composed by the porous materials (e.g., wood, [18] silica, [10] etc.) for Solar steam generation has been proven to be one of the most efficient approaches for harvesting solar energy for diverse applications such as distillation, desalination, and production of freshwater. Here, the synthesis of monolithic carbon aerogels by facile carbonization of conjugated microporous polymer nanotubes as efficient solar steam generators is reported. The monolithic carbon-aerogel networks consist of randomly aggregated hollow-carbon-nanotubes (HCNTs) with 100-250 nm in diameter and a length of up to several micrometers to form a hierarchically nanoporous network structure. Treatment of the HCNTs aerogels with an ammonium peroxydisulfate/sulfuric acid solution endows their superhydrophilic wettability which is beneficial for rapid transportation of water molecules. ...

A 3D‐Structured Sustainable Solar‐Driven Steam Generator Using Super‐Black Nylon Flocking Materials

“…Beside an ideal solar absorbing performance, the vertically aligned array of BNF flocking board possesses a unique water self‐supply ability simultaneously, which makes the liquid transport rapidly due to the wicking effect . The surface wettability has been considered as one of the important factors for water transportation during evaporation . The images (Figure S2, Supporting Information) captured by a high‐speed camera showed that the water droplet spreads and wicks quickly after it touches the BNF flocking board surface.…”

Superhydrophilic and Oleophobic Porous Architectures Based on Basalt Fibers as Oil‐Repellent Photothermal Materials for Solar Steam Generation

“…To further clarify the surface chemical properties of BFT, X‐ray photoelectron spectroscopy (XPS) was carried out (Figure d). With a carbon concentration of 76.00 %, BFT gave a C 1s spectra that can be deconvoluted into two peaks (Figure e), which can be attributed to aliphatic carbon (285.0 eV) and ether linkages or alcohol groups (285.4 eV) . The oxygen concentration was 23.14 % and the O 1s spectrum could be deconvoluted into two peaks (Figure f), which, were assigned to alumina (531.1 eV) and silica (532.5 eV).…”

Sugarcane‐Based Photothermal Materials for Efficient Solar Steam Generation

“…The severe environmental pollution issues as well as energy crisis has aroused the emphases for development of clean and renewable energy resource . Among a variety of sustainable energy resources, solar energy has long been considered as green and unexhausted energy which has been the hot points of various kinds of sustainable energy . As a kind of solar energy utilization manner, in recent years, the use of photothermal materials for solar steam generation has received considerable attention both in academy and industry due to their high evaporation rate along with high solar energy conversion efficiency by comparison with that of common bulk water vaporization .…”