Hydrophobic/Hydrophilic Cooperative Janus System for Enhancement of Fog Collection

Abstract

Harvesting micro-droplets from fog is a promising method for solving global freshwater crisis. Different types of fog collectors have been extensively reported during the last decade. The improvement of fog collection can be attributed to the immediate transportation of harvested water, the effective regeneration of the fog gathering surface, etc. Through learning from the nature's strategy for water preservation, the hydrophobic/hydrophilic cooperative Janus system that achieved reinforced fog collection ability is reported here. Directional delivery of the surface water, decreased re-evaporation rate of the harvested water, and thinner boundary layer of the collecting surface contribute to the enhancement of collection efficiency. Further designed cylinder Janus collector can facilely achieve a continuous process of efficient collection, directional transportation, and spontaneous preservation of fog water. This Janus fog harvesting system should improve the understanding of micro-droplet collection system and offer ideas to solve water resource crisis.

Bioinspired Special Wettability Surfaces: From Fundamental Research to Water Harvesting Applications

“…During the water‐harvesting test, they found more rapid, spontaneous, directional transportation, and continuous in the 3D Janus system than in the 2D due to the boundary layer effect. The finding provides a novel approach to the fabrication of the fog harvesting system …”

One‐Way Water‐Transport Cotton Fabrics with Enhanced Cooling Effect

“…[1][2][3][4][5] UV irradiation, electrospinning, plasma treatment, and one-sided coating were employed to attain special wettability profi les. They are prepared by forming either a lyophilic-to-lyophobic gradient throughout the fabric thickness or a lyophilic/ lyophobic Janus surface on the fabric.…”

“…They are prepared by forming either a lyophilic-to-lyophobic gradient throughout the fabric thickness or a lyophilic/ lyophobic Janus surface on the fabric. [ 4,[6][7][8][9][10] The unique applications of the directional fl uid-transport thin porous media on oil-water separation, [ 9,10 ] fog collection, [ 4 ] and fi ne bubble aeration [ 7 ] were uncovered. [5][6][7] Apart from Janus fabrics, Janus porous membranes with directional fl uidtransport features were reported.…”

Heat Transfer in Directional Water Transport Fabrics

“…The concept of directional fluid transport, which is also called "one-way liquid transport" or "fluid diode" is a phenomenon widely found in daily life. Examples can be found in one-dimensional (1D) materials, such as spider silk and its inspired designs for water-harvesting [9][10][11][12][13][14][15][16][17], two-dimensional (2D) solid surfaces which are fabricated typically by forming a chemical gradient [18][19][20][21][22][23], or chemically homogeneous but surface roughness variation [24][25][26][27][28] using various approaches, and three-dimensional (3D) porous materials such as textile fabrics [1,[5][6][7][29][30][31][32][33], cellulosic paper substrate [34], and electrospun nanofibrous membranes [3,7]. The 3D porous materials with directional water transport property are prepared either by forming a hydrophobicity-to-hydrophilicity gradient or two zones with opposite wettability across thickness.…”