Efforts to develop innovative water harvesting strategies offer powerful solutions to alleviate the water crisis,especially in remote and arid areas.Inspired by the hydrophobic/hydrophilic pattern of desert beetles an...Efforts to develop innovative water harvesting strategies offer powerful solutions to alleviate the water crisis,especially in remote and arid areas.Inspired by the hydrophobic/hydrophilic pattern of desert beetles and water self-propulsion property of spider silks,a double-strand hydrophobic PVDF-HFP/hydrophilic PAN nanofibers yarn is proposed by electrospinning and twisting techniques.The double-strand cooperation approach allows for water deposition on hydrophobic PVDF-HFP segment and transport under the asymmetric capillary driving force of hydrophilic PAN segment,thus speeded up the aggregation and growth of droplets.The effects of the composition and the diameter ratio of the two primary yarns were studied and optimized for boosting fog collection performance.The double-strand anisotropic yarn not only provide an effective method for water harvesting,but also hold the potential to inspire innovative design concepts for fog collection materials in challenging environments.展开更多
Efflcient collection of water from fog can effectively alleviate the problem of water shortages in foggy but water-scarce areas,such as deserts,islands and so on.Unlike inefflcient fog meshes,corona discharge can char...Efflcient collection of water from fog can effectively alleviate the problem of water shortages in foggy but water-scarce areas,such as deserts,islands and so on.Unlike inefflcient fog meshes,corona discharge can charge water droplets and further enhance the water-collecting effect.This study proposes a novel multi-electrode collecting structure that can achieve efflcient and direction-independent water collection from fog.The multi-electrode structure consists of three parts:a charging electrode,an intercepting electrode and a ground electrode.Four types of watercollecting structures are compared experimentally,and the collection rates from a traditional fog mesh,a wire-mesh electrode with fog coming from a high-voltage electrode,a wire-mesh electrode with fog coming from a ground electrode and a multi-electrode structure are 2–3 g h^(-1),100–120 g h^(-1),60–80 g h^(-1)and 200–220 g h^(-1),respectively.The collection rate of the multielectrode structure is 100–150 times that of a traditional fog mesh and 2–4 times that of a wiremesh electrode.These results demonstrate the superiority of the multi-electrode structure in fog collection.In addition,the motion equation of charged droplets in an electric fleld is also derived,and the optimization strategy of electrode spacing is also discussed.This structure can be applied not only to fog collection,but also to air puriflcation,factory waste gas treatment and other flelds.展开更多
As a century-old concept,superwettability has aroused the interest of researchers in the past decades,attributed to the discoveries of the mechanisms of special wetting phenomena in nature.Bio-inspired manufacturing o...As a century-old concept,superwettability has aroused the interest of researchers in the past decades,attributed to the discoveries of the mechanisms of special wetting phenomena in nature.Bio-inspired manufacturing of superwetting surfaces for fog collection and anti-icing applications has become mainstream research,potentially alleviating the problem of water shortage and ice accidents.Superwetting surfaces for fog collection and anti-icing applications involve a reverse process,in which the former gathers water spontaneously,while the latter repels water.Contrastive analysis of the two is essential for the comprehensive understanding of superhydrophilic/superhydrophobic surfaces and boosting their applications.Herein,wetting theories and basic mechanisms for fog collection and anti-icing are briefly introduced.Then,manufacturing methods of bionic structures and surfaces are systematically reviewed after discussing the typical organisms with superwettability.Finally,conclusions are drawn and prospects for future development are proposed.展开更多
We demonstrate the application of cactus-inspired structures for fog collection. The drop-on-cone system is modeled to analyze Gibbs free-energy gradients, equilibrium positions and motion of drops. Normalized free en...We demonstrate the application of cactus-inspired structures for fog collection. The drop-on-cone system is modeled to analyze Gibbs free-energy gradients, equilibrium positions and motion of drops. Normalized free energy and free energy gra- dient are presented to characterize barrel and clam-shell drops, revealing the relations of the driving force and wettability to the half-apex angle of the cones. Small half-apex angle results in long collecting length and weak driving force. Thus it is important for fog collection to balance the driving force and collecting length with a suitable half-apex angle. Fog collection experiments on cactus-inspired structures are conducted for verification. Inflection points around 1.1° are observed, where the fog collection ability is mainly limited by the weak driving force when below the inflection points, while increases with the collecting length when above the inflection points. These indicate that the half-apex angle at the inflection point is a compromise between the driving force and collecting length, agreeing with the normalized functions. The results also prove that the hydrophilic cones are more suitable for fog collection with regard to condensation and driving force. Our research offers design guidance for efficient fog collection structure.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.22105012,21975007,22175007 and 52172080)Beijing Natural Science Foundation(Nos.2242035,2242041,2232054 and 2232037)+5 种基金the National Natural Science Foundation for Outstanding Youth Foundationthe Fundamental Research Funds for the Central Universitiesthe National Program for Support of Top-notch Young Professionalsthe 111 project(No.B14009)the Youth Excellence Project of Beijing Institute of Graphic Communication(No.Ea202403)the Scientific Research Foundation of Beijing Institute of Graphic Communication(No.27170124031)。
文摘Efforts to develop innovative water harvesting strategies offer powerful solutions to alleviate the water crisis,especially in remote and arid areas.Inspired by the hydrophobic/hydrophilic pattern of desert beetles and water self-propulsion property of spider silks,a double-strand hydrophobic PVDF-HFP/hydrophilic PAN nanofibers yarn is proposed by electrospinning and twisting techniques.The double-strand cooperation approach allows for water deposition on hydrophobic PVDF-HFP segment and transport under the asymmetric capillary driving force of hydrophilic PAN segment,thus speeded up the aggregation and growth of droplets.The effects of the composition and the diameter ratio of the two primary yarns were studied and optimized for boosting fog collection performance.The double-strand anisotropic yarn not only provide an effective method for water harvesting,but also hold the potential to inspire innovative design concepts for fog collection materials in challenging environments.
基金supported by the National Key Research and Development Program of China(Nos.2016YFC0401002 and 2016YFC0401006)National Natural Science Foundation of China(Nos.51577080 and 51821005)。
文摘Efflcient collection of water from fog can effectively alleviate the problem of water shortages in foggy but water-scarce areas,such as deserts,islands and so on.Unlike inefflcient fog meshes,corona discharge can charge water droplets and further enhance the water-collecting effect.This study proposes a novel multi-electrode collecting structure that can achieve efflcient and direction-independent water collection from fog.The multi-electrode structure consists of three parts:a charging electrode,an intercepting electrode and a ground electrode.Four types of watercollecting structures are compared experimentally,and the collection rates from a traditional fog mesh,a wire-mesh electrode with fog coming from a high-voltage electrode,a wire-mesh electrode with fog coming from a ground electrode and a multi-electrode structure are 2–3 g h^(-1),100–120 g h^(-1),60–80 g h^(-1)and 200–220 g h^(-1),respectively.The collection rate of the multielectrode structure is 100–150 times that of a traditional fog mesh and 2–4 times that of a wiremesh electrode.These results demonstrate the superiority of the multi-electrode structure in fog collection.In addition,the motion equation of charged droplets in an electric fleld is also derived,and the optimization strategy of electrode spacing is also discussed.This structure can be applied not only to fog collection,but also to air puriflcation,factory waste gas treatment and other flelds.
基金supported by the National Natural Science Foundation of China(Grant Nos.51222508 and 51175210)。
文摘As a century-old concept,superwettability has aroused the interest of researchers in the past decades,attributed to the discoveries of the mechanisms of special wetting phenomena in nature.Bio-inspired manufacturing of superwetting surfaces for fog collection and anti-icing applications has become mainstream research,potentially alleviating the problem of water shortage and ice accidents.Superwetting surfaces for fog collection and anti-icing applications involve a reverse process,in which the former gathers water spontaneously,while the latter repels water.Contrastive analysis of the two is essential for the comprehensive understanding of superhydrophilic/superhydrophobic surfaces and boosting their applications.Herein,wetting theories and basic mechanisms for fog collection and anti-icing are briefly introduced.Then,manufacturing methods of bionic structures and surfaces are systematically reviewed after discussing the typical organisms with superwettability.Finally,conclusions are drawn and prospects for future development are proposed.
基金The authors are grateful for financial support from the National Natural Science Foundation of China （Grant Nos. 51305129 and 51222508）, and the Program for Changjiang Scholars and Innovative Research Team in University （No. IRT13017）.
文摘We demonstrate the application of cactus-inspired structures for fog collection. The drop-on-cone system is modeled to analyze Gibbs free-energy gradients, equilibrium positions and motion of drops. Normalized free energy and free energy gra- dient are presented to characterize barrel and clam-shell drops, revealing the relations of the driving force and wettability to the half-apex angle of the cones. Small half-apex angle results in long collecting length and weak driving force. Thus it is important for fog collection to balance the driving force and collecting length with a suitable half-apex angle. Fog collection experiments on cactus-inspired structures are conducted for verification. Inflection points around 1.1° are observed, where the fog collection ability is mainly limited by the weak driving force when below the inflection points, while increases with the collecting length when above the inflection points. These indicate that the half-apex angle at the inflection point is a compromise between the driving force and collecting length, agreeing with the normalized functions. The results also prove that the hydrophilic cones are more suitable for fog collection with regard to condensation and driving force. Our research offers design guidance for efficient fog collection structure.
