A single-layer Janus membrane with dual gradient conical micropore arrays for self-driving fog collection

Ren, Feifei; Li, Guoqiang; Zhang, Zhen; Zhang, Xuedong; Fan, Hua; Zhou, Chen; Wang, Yulong; Zhang, Yinghui; Wang, Chaowei; Mu, Kai; Su, Yahui; Wu, Dong

doi:10.1039/c7ta04392a

Cited by 111 publications

(80 citation statements)

References 29 publications

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“…In this process, fog droplets (liquid phase) are collected from humid air (gas phase). Among hydrophilic, hydrophobic, and Janus membranes, the Janus ones show the highest water collection efficiency whereas the hydrophobic ones are the poorest (Figure h,i) . This relationship is easy to understand because the water droplets are difficult to transport through the hydrophobic membrane.…”

Section: Promote Energy Efficiency By Asymmetrymentioning

confidence: 93%

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Janus Membranes: Creating Asymmetry for Energy Efficiency

et al. 2018

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Membranes are recognized as a key component in many environment and energy-related applications, but conventional membranes are challenged to satisfy the growing demand for ever more energy-efficient processes. Janus membranes, a novel class with asymmetric properties on each side, have recently emerged and represent enticing opportunities to address this challenge. With an inner driving force arising from their asymmetric configuration, Janus membranes are appealing for enhancing energy efficiency in a variety of membrane processes by promoting the desired transport. Here, the fundamental principles to prepare Janus membranes with asymmetric surface wettability and charges are summarized, and how they work in conventional and unconventional membrane processes is demonstrated.

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Section: Promote Energy Efficiency By Asymmetrymentioning

confidence: 93%

Section: Promote Energy Efficiency By Asymmetrymentioning

confidence: 99%

Janus Membranes: Creating Asymmetry for Energy Efficiency

et al. 2018

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“…Such divergent surface properties have led to Janus membranes finding applications in a host of challenging fluid manipulations. Recently reported Janus membrane structures demonstrate applications in battery separators, oil/water emulsification and de‐emulsification, fog harvesting, blood plasma separation, membrane distillation/nanofiltration, and fine bubble aeration …”

Section: Introductionmentioning

confidence: 99%

Janus Membranes via Diffusion‐Controlled Atomic Layer Deposition

Waldman

Yang

Mandia

et al. 2018

Adv Materials Inter

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The first use of atomic layer deposition (ALD) to produce Janus membranes is reported, with an example system consisting of a compositional gradient ranging from hydrophilic Al2O3 on one face to hydrophobic poly(propylene) on the opposite face. Alternating pulses of trimethyl aluminum and water vapor lead to the growth of covalently bonded Al2O3 conforming to the membrane pore surfaces. Precise control of ALD parameters significantly affects the surface wetting of the modified membrane face and the depth of Al2O3 infiltration into the porosity. This depth control derives from slow precursor diffusion through the 200 nm membrane pores compared to much faster ALD surface reactions. For a given precursor exposure and purge time, increasing the number of ALD cycles decreases the water contact angle at the modified surface from hydrophobic to hydrophilic, until the water droplet is completely imbibed by the membrane. To demonstrate the utility of these Janus membranes, a hydrophilic/superaerophobic Janus treatment is shown to greatly reduce the size of air bubbles generated through the membrane, enabling faster mixing. This technique represents the first application of vapor‐deposited covalently bonded metal oxides to form Janus membranes. Further opportunities are afforded by the ability to laterally pattern Al2O3 across the membrane surface via physical masking.

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“…First, high-uniformity micropore arrays were fabricated by femtosecond laser micro-drilling. [21][22][23][24][25] Then, the doublefaced superhydrophilic aluminum foil was modified by low surface energy fluorosilane, and the sample turned into double-faced superhydrophobicity. Subsequently, Janus aluminum foil was obtained by laser scanning to remove a part of the PFDTES-modified material on the bottom surface.…”

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confidence: 99%

Unidirectional self-transport of air bubble via a Janus membrane in aqueous environment

Yan

Ren

et al. 2018

Applied Physics Letters

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Inspired by natural creatures, bubble manipulation by surface microstructures in aqueous media has attracted great attention due to its promising applications in industrial production. Herein, a superhydrophobic/hydrophilic Janus aluminum membrane with tapered micropore arrays was fabricated by femtosecond laser drilling, surface fluorination, and subsequent fluorination removal. Compared with the single interception or penetration of double-faced hydrophilic or superhydrophobic membranes, the Janus membrane showed a distinctive unidirectional air bubble transport ability. In experiment, the air bubbles introduced on the lower hydrophilic surface could spontaneously move to the upper superhydrophobic surface, but they were prevented in the inverse direction. The dynamic process of unidirectional transport was in-situ monitored, and the physical mechanism was systemically investigated. In addition, the concepts of air-participating chemical/physical processes were demonstrated such as discoloration of purple litmus solution by CO2 injection, which proved the Janus membrane practicability.

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A single-layer Janus membrane with dual gradient conical micropore arrays for self-driving fog collection

Abstract: Inspired by natural creatures, the development of a device that collects water from fog represents an important research direction.

Cited by 111 publications

References 29 publications

Janus Membranes: Creating Asymmetry for Energy Efficiency

Janus Membranes: Creating Asymmetry for Energy Efficiency

Janus Membranes via Diffusion‐Controlled Atomic Layer Deposition

Unidirectional self-transport of air bubble via a Janus membrane in aqueous environment

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