The authors acknowledge support from Samsung, the NC State Chancellors Innovation Funds, NSF (CAREER CMMI-0954321 and Triangle MRSEC DMR-1121107), and Air Force Research Labs.

1.操纵液态金属在电解液的界面张力<ol><li>氧化<ol><li>倾的含水电解质（酸性或碱性）到培养皿。以确保该氧化物完全除去，可使用的酸或碱与浓度大于0.1M的24（如1 M氢氧化钠或1M的HCl）。使用体积，将填补菜到大约1-3毫米的深度。避免与这些解决方案的皮肤接触。 </li><li>用注射器放置在该电解质的镓基合金的下降（最佳之间10-500微升）。实例包括共晶镓铟（EGAIN）或镓铟锡（Galinstan）。如果纯镓时，暖电解质到至少30℃，以防止冻结。 </li><li>放置一个铜线到液体金属建立工作电极。使用铜线的直径小于所述下降，以及使用根据数字万用表制造商的说明步骤ensure该导线具有的&lt;1Ω的电阻。在酸或碱，液体金属将润湿铜，从而形成良好的电接触。 </li><li>放置一个导电对电极（如铜，石墨，铂等 ）在溶液中，但不与金属液接触。如果反电极具有&lt;1Ω的电阻，它的尺寸是不相关的。 </li><li>的电线连接到一个电压源和施加正电位加到液态金属。对于小的形状变形，应用正电压&lt;1 V.对于较大的形状的变形（和液体金属朝向反电极的移动），申请&gt; 1 V 注意:溶液的浓度，并从反电极下降的距离决定以诱导改变界面张力以来的电化学表面氧化的速率竞争与氧化物溶解的电解质的速率所需的电压。 </li></ol></l我&gt; <li>减少<ol><li>分配液体金属的压降（10-500微升）从注射器到一个空的皮氏培养皿。 </li><li>倾的中性水电解质放入培养皿（例如1M的氟化钠（NaF）或1M氯化钠（NaCl）中），以该浸没金属的水平。 注意:使用酸性（pH值&lt;3）或碱性溶液（pH&gt; 10）将导致氧化物自发地溶解。 </li><li>放置一个铜线到液体金属作为工作电极，和一导线（例如，铜）到电解质作为反电极。 </li><li>的电线连接到一个电压源和施加负电位加到液态金属。应用大约-1V时，除去表面氧化膜，导致金属从基材dewet。金属应dewet上最接近一边对电极。 </li><li>施加更大的负电位（&lt;-1Ⅴ）完全去除氧化物层。避免将excessively大的负电压，以防止氢气泡从出现在液态金属由于还原电解质。 </li></ol></li></ol>通过固着液滴2.表面张力测量<ol><li>使用激光切割机或铣削刀具，切割距离市中心的直接路径一块聚甲基丙烯酸甲酯（约1毫米厚）的边缘，不要一路过关斩将的PMMA的厚度切的路径。只有削减约一半。这一块将作为底物的液体金属。其它平面和电绝缘材料，如玻璃，陶瓷，或聚合物也可以作为基材。 </li><li>使用相同的工具，切断通过聚甲基丙烯酸甲酯的中心的1毫米2孔。 </li><li>利用路径作为引导，只有暴露在聚甲基丙烯酸甲酯的中心的前端运行绝缘铜线。定位导线，以便它突出在PMMA表面。密封线到位了防漏胶。切导线只是聚甲基丙烯酸甲酯的表面上方，但不让它延伸太远（超出〜100微米），或者它会扰乱滴的形状。 </li><li>磁带上的​​聚甲基丙烯酸甲酯片分解成通过其能够获得清晰的图像的透明容器。填充容器用1M的NaOH，然后将液态金属的25-50微升滴在突出铜线。此线将作为工作电极和将润湿液滴。 </li><li>放置一个铂网状反电极和饱和银/氯化银（银/氯化银）参考电极，在溶液中。连接所有的电极，以恒电位。 </li><li>放置在容器中的接触角测角仪，使液滴的表面轮廓清晰可见。使用恒电位仪来控制电压相对于参考电极，并使用测角器来测量的形状和下降，从而界面张力。确保测角仪能够测量座滴界面tensi的上;但也可以使用从一个水平安装的照相机25拍摄的图像降定制轴对称形状分析。 </li></ol> 3.毛细管注入<ol><li>填充的1M氢氧化钠的溶液的玻璃毛细管。毛细管直径应为约1毫米。 </li><li>放置针对一滴液态金属的毛细平齐的一端。对准毛细管，使得它与表（即，垂直于重力）的表面平行。避免液态金属下跌，电解质填充毛细管之间的空气间隙。使用擦拭，轻拍掉任何多余的电解液可能在装配过程中已经泄漏。 </li><li>放置一个铜线（工作电极）的液态金属，和导电对电极（例如铜线）在毛细管的开口端，使得它接触溶液。 </li><li>的电线连接到一个电压源和施加正电位加到液态金属。液态金属应该开始填写的Capillary（避免出现大的潜力，这将导致在反电极过量泡沫的形成）。 </li></ol> 4.毛细管提款<ol><li>利用软光刻26和复制成型技术制造聚二甲基硅氧烷（PDMS）组成的微流体通道。制作渠道是约100至1000微米宽，100微米高，而25至65毫米长。 注:通道尺寸1000微米宽，100微米高，65毫米长的通道产生一致的结果，但其他人也可以正常工作。另外，使用玻璃毛细管（例如，1毫米直径，硼硅玻璃）代替PDMS微通道。 </li><li>注入液态金属手动或使用注射泵，以完全填充通道任一（即，6.5毫米3为1000微米宽，100微米高，和65毫米长的信道）。 </li><li>使用已经浸渍在1M的NaOH或1M的HCl棉签，除去里的过量从通道的所述入口（和，如果需要的话，出口）嚼食金属，使得金属保持与PDMS的顶面齐平。 </li><li>淹没在电解液（如，1M NaCl）中的通道的一端，并放置在阳极（例如，铜，铂，或钨的金属丝），使得其接触电解质而不是金属。 </li><li>在通道的另一端，与一个单独的电极（例如，铜导线）在金属表面上，使液体金属本身作为阴极。 </li><li>连接这些电线（即，阳极和阴极），以一电压源或恒电位，并完成电路。用于三电极系统中，放置基准电极，使得它几乎没有浸没入电解液的下降。 </li><li>之前进行还原电压，安装在三脚架上，或在显微镜摄像机记录实验。使用自动对焦模式，以获得一切的焦点。利用手动对焦有一个更好的控制景深，白平衡，及ISO的。根据需要，使用较高的光圈值（ 即 11或更高版本），1/100快门，自动白平衡和自动ISO。 </li><li>开始录制的实验。应用大约-1 V到从微通道撤出液体金属。转电压关闭，以使金属以停止移动的中性电解质。 </li></ol>

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The authors have nothing to disclose.

<html>此方法控制使用小电压来驱动的表面氧化物的沉积和去除镓基液体金属的表面张力。尽管该方法只适用于在电解质溶液，它简单，和工作在多种不同的条件，但也有微妙之处值得​​留意。在无电势的，酸性和碱性溶液蚀刻掉氧化物27。的氧化电势的应用驱动表面氧化物在所有水电解液，包括酸性和碱性溶液的形成。然而，该氧化物在酸性或碱性溶液溶解竞争与氧化物的沉积，以防止...

This method provides a simple way to control the surface tension of liquid metals containing gallium. The method uses modest voltages (~1 V) applied directly to the liquid metal (relative to a counter electrode in the presence of electrolyte) to achieve enormous and reversible changes to the surface tension of the metal1. 
Surface tension is a dominant force for liquids at small length scales and is important for a number of capillary phenomena including wetting, spreading, and surface-tension driven flow. Consequently, the ability to control surface tension is a sensible way to manipulate the shape, position, and flow of liquids at sub-mm length scales. The most common way to alter surface tension between two fluids is to use a surfactant, which is a molecule that spans the interface between the fluids. Surfactants lower surface tension, but in a way that is not easy to reverse since it is difficult to remove surfactants from the interface. Surface tension can also be altered using a variety of techniques, including temperature gradients2,3, light4, surface chemistry5-7,and voltage8. But most of these methods result in modest changes to surface tension, particularly for liquid metals, which have notably large surface tensions.
The ability to control the surface tension of liquid metal could enable new opportunities for creating shape reconfigurable structures with metallic properties for electronic, thermal, and optical applications9-14. The most common liquid metal is Hg, which is noted for its toxicity. The methods described here are relevant for liquid metals based on gallium. These metals have low viscosity, large surface tension, low volatility (low vapor pressure), and low toxicity15. Importantly, these metals form surface oxides composed of gallium oxide that are a few nm thick in air16. This oxide layer creates a physical skin that historically has been a nuisance for electrochemical and fluid dynamic applications17. The method here utilizes the oxide in new ways to control surface tension.
The most common way to manipulate liquid metals in electrolyte is to apply a potential to the metal relative to a counter electrode18. Oppositely charged ions from the electrolyte match the charges on the metal, causing the interfacial tension to drop. This phenomenon-termed electrocapillarity-has been known since the 1870s as described by Lippman19and has been utilized for alloys of gallium20. Typically, electrocapillarity achieves modest changes to surface tension, since undesirable electrochemical reactions limit the range of voltages applied to the metal. In contrast, the method described here utilizes the surface oxidation of the metal (or conversely, the reduction of the surface oxide) as a way to achieve enormous changes in surface tension above and beyond changes resulting from electrocapillarity. The leading explanation for this phenomenon is that the oxide is asymmetric; that is, the outer surface of the oxide terminates with hydroxyl groups (making a low interfacial tension interface with the aqueous electrolyte), and the interior surface of the oxide terminates with gallium atoms (making a low interfacial tension interface with the metal). In contrast, the removal of the oxide via electrochemical reduction results in a bare metal-electrolyte interface, which returns the metal back to a state of high surface tension. We characterize the interfacial tension of the metal by analyzing the shape of sessile droplets as a function of voltage while assuming that gravity and surface tension are the dominant forces that define the curvature of its surface. 
The advantage of this technique relative to classic electrocapillarity is that it can reversibly tune the tension of low toxicity liquid metals over enormous ranges (from ~500 mN/m to near zero). This delta change in surface tension may be the largest ever reported in literature for any fluid and it can be accomplished in a tunable and reversible manner. These large changes in surface tension are useful for manipulating the capillary behavior of metals; for example, it can induce the metal to spread on a surface, withdraw the metal from microchannels, fill microchannels with metal, and overcome the Rayleigh instabilities to form liquid metal fibers1,21. 
A drawback of this technique is that it requires electrolyte. It works best in acidic or basic conditions, because these electrolytes remove excess surface oxide that would otherwise contaminate the surface of the metal and mechanically restrict the movement of the metal. The simultaneous removal and deposition of the oxide layer complicates the analysis of the interfacial phenomena and it is our hope the methods described in this paper empowers additional analysis. Another disadvantage is that the electrochemical reactions at the surface of the metal must be matched by complimentary half-reactions at the counter electrode22,23. This can lead to hydrogen bubbles forming at the counter electrode.

<table>
	<tbody>
		<tr>
			<td>Eutectic Gallium Indium</td>
			<td>Indium Corporation</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Hydroxide</td>
			<td>Fisher Scientific</td>
			<td>2318-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric Acid</td>
			<td>Fisher Scientific</td>
			<td>A481-212</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Fluoride</td>
			<td>Sigma-Aldrich</td>
			<td>201154</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical Adhesive</td>
			<td>Norland</td>
			<td>NOA81</td>
			<td></td>
		</tr>
		<tr>
			<td>Polydimethylsiloxane (Sylgard-184)</td>
			<td>Dow Corning</td>
			<td></td>
			<td>Silicone Elastomer Kit</td>
		</tr>
		<tr>
			<td>Borosilicate Glass Capillaries</td>
			<td>Friedrich and Dimmoch</td>
			<td>B41972</td>
			<td></td>
		</tr>
		<tr>
			<td>Ag/AgCl Reference Electrode</td>
			<td>Microelectrodes Inc.</td>
			<td>MI-401F</td>
			<td></td>
		</tr>
		<tr>
			<td>Voltage Source</td>
			<td>Keithley</td>
			<td>3390</td>
			<td></td>
		</tr>
		<tr>
			<td>Potentiostat</td>
			<td>Gamry</td>
			<td>Ref 600</td>
			<td></td>
		</tr>
		<tr>
			<td>Laser Cutter</td>
			<td>Universal Laser Systems</td>
			<td>VLS 3.50</td>
			<td></td>
		</tr>
	</tbody>
</table>

a method to manipulate surface tension of a liquid metal via surface oxidation and reduction

控制界面张力是一种有效的方法，用于操纵在亚毫米尺度，其中界面张力是一个主导力的形状，位置和流量的流体。有多种方法存在用于控制这种规模的含水和有机液体的界面张力;然而，这些技术具有有限的效用的液态金属，由于其大的界面张力。 液态金属可以形成在电子和电磁设备的软的，可拉伸和形状重构组件。虽然是可能的操纵通过机械方法 （例如，泵送）这些流体，电的方法是比较容易的小型化，控制和执行。然而，大多数电气技术有自己的约束:电式电介质需要大量的（千伏）潜力适度的驱动，电毛细管会影响界面张力相对较小的变化，而不断ELEctrowetting仅限于液态金属在毛细管的插头。 这里，我们提出用于通过电化学表面反应致动镓和镓基液体金属合金的方法。控制液体金属在电解质迅速的表面上的电化学势和可逆地变化的界面张力数量级超过两个数量（̴50020mN / m至接近零）。此外，这种方法只需要一个非常温和的电位（&lt;1 V）的施加相对于反电极。在张力所得变化主要是由于表面氧化层，其作为表面活性剂的电化学沉积;除去氧化的增加的界面张力，且反之亦然。这种技术可以在各种电解质被应用，是独立于所依靠的基板。

图 1A示出了用于氧化和还原的简单的两电极技术的一个例子。在这种情况下，液态金属的70微升滴置于1 M氢氧化钠溶液接触的铜线，以建立电连接。的1 M氢氧化钠去除表面氧化物从金属和能使金属水珠，由于其界面张力。施加降和铂网状反电极之间一个2.5伏电势使液滴的表面氧化并在迁移朝向反电极（图1A...

Watch this Scientific Journal Video about A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction at JoVE.com

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

方法通过表面氧化还原操纵液态金属的表面张力

We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where ...

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Liquids, Solids, and Intermolecular Forces

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15.2K 次观看.  North Carolina State University. We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

视频: A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date back to the early 1980s the focus of these early papers primarily characterized the changes to the structures under extremely harsh conditions (pH or temperature)1-3. It is also known that paramagnetic molecular oxygen undergoes a Heisenberg spin exchange interaction with stable radicals that extremely broadens the EPR signal4-6. Recently, we reported interesting results where this interaction of molecular oxygen with a certain part of the existing stable radical structure can be reversibly affected simply by flowing a diamagnetic gas through the carbon samples at STP7. As flows of He, CO2, and N2 had a similar effect these interactions occur at the surface area of the macropore system.
This manuscript highlights the experimental techniques, work-up, and analysis towards affecting the existing stable radical nature in the carbon structures. It is hoped that it will help towards further development and understanding of these interactions in the community at large.

Stable radicals that are present in carbon substrates interact with paramagnetic oxygen through a Heisenberg spin exchange. This interaction can be significantly reduced under STP conditions by flowing a diamagnetic gas over the carbon system. This manuscript describes a simple method to characterize the nature of those radicals.

通过电子顺磁共振和校准气体流量探索碳表面的激进性质

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date ...

科研

化学

Transport of Surface-modified Carbon Nanotubes through a Soil Column

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, electronics and biomedical applications. Due to their accelerating production and use, CNTs constitute a potential environmental risk if they are released to soil and groundwater systems. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs. The transport and retention of CNTs in both natural and artificial media have been reported in literature, but the findings widely vary and are thus not conclusive. There are a number of physical and chemical parameters responsible for variation in retention and transport. In this study, a complete procedure of selected multiwalled carbon nanotubes (MWCNTs) is presented starting from their surface modification to a complete set of laboratory column experiments at critical physical and chemical scenarios. Results indicate that the stability of the commercially available MWCNTs are critical with their attached surface functional group which can also influence the transport and retention of MWCNT through the surrounding medium.

Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.

表面修饰碳纳米管通过土柱运输

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, ...

Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO4)2&#183;H2O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C4H9)4NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior.

A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.

合成与盘状磷酸盐锆剥落获取胶体液晶

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and ...

Failure of Cleaning Verification in Pharmaceutical Industry Due to Uncleanliness of Stainless Steel Surface

The aim of this work is to identify the parameters that affect the recovery of pharmaceutical residues from the surface of stainless steel coupons. A series of factors were assessed, including drug product spike levels, spiking procedure, drug-excipient ratios, analyst-to-analyst variability, intraday variability, and cleaning procedure of the coupons. The lack of a well-defined procedure that consistently cleaned the coupon surface was identified as the major contributor to low and variable recoveries. Assessment of cleaning the surface of the coupons with clean-in-place solutions (CIP) gave high recovery (&#62;90%) and reproducible results (Srel&#8804;4%) regardless of the conditions that were assessed previously. The approach was successfully applied for cleaning verification of small molecules (MW &#60;1,000 Da) as well as large biomolecules (MW up to 50,000 Da).

The lack of a well-defined procedure that consistently cleaned coupon surfaces was identified as the major contributor to low and variable recoveries in cleaning verification. This manuscript describes the correct protocol of cleaning stainless steel coupons.

清洁验证在不锈钢表面脏制药行业中的失败

The aim of this work is to identify the parameters that affect the recovery of pharmaceutical residues from the surface of stainless steel coupons. A ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

通过活性表面生长机制合成基片束缚金纳米线

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various precursor noble metal ions with reducing agents in a 1:1 (v/v) ratio results in the formation of metal gels within seconds to minutes compared to much longer synthesis times for other techniques such as sol-gel. Conducting the reduction step in a microcentrifuge tube or small volume conical tube facilitates a proposed nucleation, growth, densification, fusion, equilibration model for gel formation, with final gel geometry smaller than the initial reaction volume. This method takes advantage of the vigorous hydrogen gas evolution as a by-product of the reduction step, and as a consequence of reagent concentrations. The solvent accessible specific surface area is determined with both electrochemical impedance spectroscopy and cyclic voltammetry. After rinsing and freeze drying, the resulting aerogel structure is examined with scanning electron microscopy, X-ray diffractometry, and nitrogen gas adsorption. The synthesis method and characterization techniques result in a close correspondence of aerogel ligament sizes. This synthesis method for noble metal aerogels demonstrates that high specific surface area monoliths may be achieved with a rapid and direct reduction approach.

A rapid, direct solution-based reduction synthesis method to obtain Au, Pd, and Pt aerogels is presented.

直接溶液还原法快速合成金、钯、铂气凝胶的研究

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

Surface Functionalization of Metal-Organic Frameworks for Improved Moisture Resistance

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. However, the main issue limiting their applicability is their poor stability in humid conditions. The common methods to overcome this problem involve the formation of strong metal-linker bonds by using highly charged metals, which is limited to a number of structures, the introduction of alkylic groups to the framework by post-synthetic modification (PSM) or chemical vapour deposition (CVD) to enhance overall hydrophobicity of the framework. These last two usually provoke a drastic reduction of the porosity of the material. These strategies do not permit to exploit the properties of the MOF already available and it is imperative to find new methods to enhance the stability of MOFs in water while keeping their properties intact. Herein, we report a novel method to enhance the water stability of MOF crystals featuring Cu2(O2C)4&#160;paddle-wheel units, such as HKUST (where HKUST stands for Hong Kong University of Science &#38; Technology), with the catechols functionalized with alkyl and fluoro-alkyl chains. By taking advantage of the unsaturated metal sites and the catalytic catecholase-like activity of CuII ions, we are able to create robust hydrophobic coatings through the oxidation and subsequent polymerization of the catechol units on the surface of the crystals under anaerobic and water-free conditions without disrupting the underlying structure of the framework. This approach not only affords the material with improved water stability but also provides control over the function of the protective coating, which enables the development of functional coatings for the adsorption and separations of volatile organic compounds. We are confident that this approach could also be extended to other unstable MOFs featuring open metal sites.

Robust functional catechol coatings were produced in one step by direct reaction of the material known as HKUST with synthetic catechols under anaerobic conditions. The formation of homogeneous coatings surrounding the entire crystal is ascribed to the biomimetic catalytic activity of Cu(II) dimers on the external surface of the crystals.

金属-有机框架的表面功能化改善防潮性能

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. ...

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) with a 4.6 nm pore size, and ordered silica porous matrix, SBA-15, with a 5.3 nm pore size. This work describes the surface properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the differently ordered porous materials with similar pore sizes. For this purpose, OMC and SBA-15 with highly ordered nanoporous structures are synthesized via impregnation of the silica matrix by applying a carbon precursor and by the sol-gel method, respectively. The porous structure of investigated systems is characterized by an N2 adsorption-desorption analysis at 77 K. To determine the electrochemical character of the surface of synthesized materials, potentiometric titration measurements are conducted; the obtained results for OMC shows a significant pHpzc shift toward the higher values of pH, relative to SBA-15. This suggests that investigated OMC has surface properties related to oxygen-based functional groups. To describe the surface properties of the materials, the contact angles of liquids penetrating the studied porous beds are also determined. The capillary rise method has confirmed the increased wettability of the silica walls relative to the carbon walls and an influence of the pore roughness on the fluid/wall interactions, which is much more pronounced for silica than for carbon mesopores. We have also studied the melting behavior of D2O confined in OMC and SBA-15 by applying the dielectric method. The results show that the depression of the melting temperature of D2O in the pores of OMC is about 15 K higher relative to the depression of the melting temperature in SBA-15 pores with a comparable 5 nm size. This is caused by the influence of adsorbate/adsorbent interactions of the studied matrices.

Here we report the synthesis and characterization of ordered nanoporous carbon (with a 4.6 nm pore size) and SBA-15 (with a 5.3 nm pore size). The work describes the surface and textural properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the materials.

合成纳米碳和二氧化硅矩阵的表面性能

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) ...

Bio-inspired Polydopamine Surface Modification of Nanodiamonds and Its Reduction of Silver Nanoparticles

Surface functionalization of nanodiamonds (NDs) is still challenging due to the diversity of functional groups on the ND surfaces. Here, we demonstrate a simple protocol for the multifunctional surface modification of NDs by using mussel-inspired polydopamine (PDA) coating. In addition, the functional layer of PDA on NDs could serve as a reducing agent to synthesize and stabilize metal nanoparticles. Dopamine (DA) can self-polymerize and spontaneously form PDA layers on ND surfaces if the NDs and dopamine are simply mixed together. The thickness of a PDA layer is controlled by varying the concentration of DA. A typical result shows that a thickness of ~5 to ~15 nm of the PDA layer can be reached by adding 50 to 100 &#181;g/mL of DA to 100 nm ND suspensions. Furthermore, the PDA-NDs are used as a substrate to reduce metal ions, such as Ag[(NH3)2]+, to silver nanoparticles (AgNPs). The sizes of the AgNPs rely on the initial concentrations of Ag[(NH3)2]+. Along with an increase in the concentration of Ag[(NH3)2]+, the number of NPs increases, as well as the diameters of the NPs. In summary, this study not only presents a facile method for modifying the surfaces of NDs with PDA, but also demonstrates the enhanced functionality of NDs by anchoring various species of interest (such as AgNPs) for advanced applications.

A facile protocol is presented to functionalize the surfaces of nanodiamonds with polydopamine.

纳米金刚石的生物激发多巴胺表面改性及其对银纳米粒子的还原

Surface functionalization of nanodiamonds (NDs) is still challenging due to the diversity of functional groups on the ND surfaces. Here, we demonstrate a ...

U2O5 Film Preparation via UO2 Deposition by Direct Current Sputtering and Successive Oxidation and Reduction with Atomic Oxygen and Atomic Hydrogen

We describe a method to produce U2O5 films in situ using the Labstation, a modular machine developed at JRC Karlsruhe. The Labstation, an essential part of the Properties of Actinides under Extreme Conditions laboratory (PAMEC), allows the preparation of films and studies of sample surfaces using surface analytical techniques such as X-ray and ultra-violet photoemission spectroscopy (XPS and UPS, respectively). All studies are made in situ, and the films, transferred under ultra-high vacuum from their preparation to an analyses chamber, are never in contact with the atmosphere. Initially, a film of UO2 is prepared by direct current (DC) sputter deposition on a gold (Au) foil then oxidized by atomic oxygen to produce a UO3 film. This latter is then reduced with atomic hydrogen to U2O5. Analyses are performed after each step involving oxidation and reduction, using high-resolution photoelectron spectroscopy to examine the oxidation state of uranium. Indeed, the oxidation and reduction times and corresponding temperature of the substrate during this process have severe effects on the resulting oxidation state of the uranium. Stopping the reduction of UO3 to U2O5 with single U(V) is quite challenging; first, uranium-oxygen systems exist in numerous intermediate phases. Second, differentiation of the oxidation states of uranium is mainly based on satellite peaks, whose intensity peaks are weak. Also, experimenters should be aware that X-ray spectroscopy (XPS) is a technique with an atomic sensitivity of 1% to 5%. Thus, it is important to obtain a complete picture of the uranium oxidation state with the entire spectra obtained on U4f, O1s, and the valence band (VB). Programs used in the Labstation include a linear transfer program developed by an outside company (see Table of Materials) as well as data acquisition and sputter source programs, both developed in-house.

U2O5 Film Preparation via UO2 Deposition by Direct Current Sputtering and Successive Oxidation and Reduction with Atomic Oxygen and Atomic Hydrogen

This protocol presents the preparation of U2O5 thin films obtained in situ under ultra-high vacuum. The process involves oxidation and reduction of UO2 films with atomic oxygen and atomic hydrogen, respectively.

利用uo2沉积制备 u2o5 薄膜, 利用原子氧和原子氢连续氧化还原

We describe a method to produce U2O5 films in situ using the Labstation, a modular machine developed at JRC Karlsruhe. The Labstation, an essential part ...