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Type: Article × Subject: contact angle ×

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Now showing 1 - 3 of 3
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    Hydrophilic non-precious metal nitrogen-doped carbon electrocatalysts for enhanced efficiency in oxygen reduction reaction
    (Cambridge : Royal Society of Chemistry, 2015) Hao, Guang-Ping; Sahraie, Nastaran Ranjbar; Zhang, Qiang; Krause, Simon; Oschatz, Martin; Bachmatiuk, Alicja; Strasser, Peter; Kaskel, Stefan
    Exploring the role of surface hydrophilicity of non-precious metal N-doped carbon electrocatalysts in electrocatalysis is challenging. Herein we discover an ultra-hydrophilic non-precious carbon electrocatalyst, showing enhanced catalysis efficiency on both gravimetric and areal basis for oxygen reduction reaction due to a high dispersion of active centres.
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    Universal emulsion stabilization from the arrested adsorption of rough particles at liquid-liquid interfaces
    ([London] : Nature Publishing Group UK, 2017) Zanini, Michele; Marschelke, Claudia; Anachkov, Svetoslav E.; Marini, Emanuele; Synytska, Alla; Isa, Lucio
    Surface heterogeneities, including roughness, significantly affect the adsorption, motion and interactions of particles at fluid interfaces. However, a systematic experimental study, linking surface roughness to particle wettability at a microscopic level, is currently missing. Here we synthesize a library of all-silica microparticles with uniform surface chemistry, but tuneable surface roughness and study their spontaneous adsorption at oil-water interfaces. We demonstrate that surface roughness strongly pins the particles' contact lines and arrests their adsorption in long-lived metastable positions, and we directly measure the roughness-induced interface deformations around isolated particles. Pinning imparts tremendous contact angle hysteresis, which can practically invert the particle wettability for sufficient roughness, irrespective of their chemical nature. As a unique consequence, the same rough particles stabilize both water-in-oil and oil-in-water emulsions depending on the phase they are initially dispersed in. These results both shed light on fundamental phenomena concerning particle adsorption at fluid interfaces and indicate future design rules for particle-based emulsifiers.
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    Preparation and Application of ZIF-8 Thin Layers
    (Basel : MDPI, 2021) Schernikau, Martin; Sablowski, Jakob; Gonzalez Martinez, Ignacio Guillermo; Unz, Simon; Kaskel, Stefan; Mikhailova, Daria
    Herein we compare various preparation methods for thin ZIF-8 layers on a Cu substrate for application as a host material for omniphobic lubricant-infused surfaces. Such omniphobic surfaces can be used in thermal engineering applications, for example to achieve dropwise condensation or anti-fouling and anti-icing surface properties. For these applications, a thin, conformal, homogeneous, mechanically and chemically stable coating is essential. In this study, thin ZIF-8 layers were deposited on a Cu substrate by different routes, such as (i) electrochemical anodic deposition on a Zn-covered Cu substrate, (ii) doctor blade technique for preparation of a composite layer containing PVDF binder and ZIF-8, as well as (iii) doctor blade technique for preparation of a two-layer composite on the Cu substrate containing a PVDF-film and a ZIF-8 layer. The morphology and topography of the coatings were compared by using profilometry, XRD, SEM and TEM techniques. After infusion with a perfluorinated oil, the wettability of the surfaces was assessed by contact angle measurements, and advantages of each preparation method were discussed.