An innovative strategy is proposed to synthesize single‐crystal nanowires (NWs) of the Al3+ dicarboxylate MIL‐69(Al) MOF by using graphene oxide nanoscrolls as structure‐directing agents. MIL‐69(Al) NWs with an average diameter of 70±20 nm and lengths up to 2 μm were found to preferentially grow along the [001] crystallographic direction. Advanced characterization methods (electron diffraction, TEM, STEM‐HAADF, SEM, XPS) and molecular modeling revealed the mechanism of formation of MIL‐69(Al) NWs involving size‐confinement and templating effects. The formation of MIL‐69(Al) seeds and the self‐scroll of GO sheets followed by the anisotropic growth of MIL‐69(Al) crystals are mediated by specific GO sheets/MOF interactions. This study delivers an unprecedented approach to control the design of 1D MOF nanostructures and superstructures.
An atomistic model of the metal-organic framework (MOF) ZIF-8/graphene oxide (GO) interface has been constructed using a combination of density functional theory calculations and force-field-based molecular dynamics simulations. Two microscopic models of GO were constructed integrating basal plane and both basal and edge plane functional groups, called GO-OH and GO-COH, respectively. Analysis of the MOF/GO site-to-site interactions, surface coverage, and GO conformation/stiffness and a full characterization of the interfacial region is provided with a special emphasis on the influence of the chemical composition of GO. It was evidenced that the structure of the GO/ZIF-8 composite at the interface is stabilized by a relatively homogeneous set of interactions between the hydrogen atoms of the -NH and -OH terminal functions of ZIF-8 and the oxygen atoms of the epoxy, hydroxyl, and carboxylic groups of GO, leading to an optimal coverage of the MOF surface by GO. Such a scenario implies a significant distortion of the first GO layer brought into contact with the MOF surface, leading to an interfacial region with a relatively small width. This computational exploration strongly suggests that a very good compatibility between these two components would lead, in turn, to the preparation of defect-free ZIF-8/GO films. These predictions are correlated with an experimental effort that consists of successfully prepared homogeneous MOF/GO films that were further characterized by transmission electron microscopy and mechanical testing.
We report the potential-dependent interactions of trimesic acid with Cu surfaces in EtOH. CV experiments and electrochemical surface-enhanced Raman spectroscopy show the presence of an adsorbed trimesic acid layer on Cu at potentials lower than 0 V vs Cu. The BTC coverage increases as the potential increases, reaching a maximum at 0 V. Based on molecular dynamics simulations, we report adsorption geometries and possible structures of the organic adlayer. We find that, depending on the crystal facet, trimesic acid adsorbs either flat or with one or two of the carboxyl groups facing the metal ACCEPTED MANUSCRIPT surface. At higher coverages, a multi-layer forms that is composed mostly of flat-lying trimesic acid molecules. Increasing the potential beyond 0 V activates the Cu-adsorbate interface in such a way that under oxidation of Cu to Cu 2+ , a 3-D metal-organic framework forms directly on the electrode surface.
An innovative strategy is proposed to synthesize single‐crystal nanowires (NWs) of the Al3+ dicarboxylate MIL‐69(Al) MOF by using graphene oxide nanoscrolls as structure‐directing agents. MIL‐69(Al) NWs with an average diameter of 70±20 nm and lengths up to 2 μm were found to preferentially grow along the [001] crystallographic direction. Advanced characterization methods (electron diffraction, TEM, STEM‐HAADF, SEM, XPS) and molecular modeling revealed the mechanism of formation of MIL‐69(Al) NWs involving size‐confinement and templating effects. The formation of MIL‐69(Al) seeds and the self‐scroll of GO sheets followed by the anisotropic growth of MIL‐69(Al) crystals are mediated by specific GO sheets/MOF interactions. This study delivers an unprecedented approach to control the design of 1D MOF nanostructures and superstructures.
Advanced modeling and experimental characterization tools were coupled to gain an unprecedented in-depth characterization of the interface formed when a hybrid porous solid ZIF-8 is incorporated as filler onto an amine-functionalized graphene oxide (GO) matrix. As a preliminary stage, an aminopyridine-functionalized GO was synthesized, and a realistic atomistic model was computationally built integrating their structural and chemical features deduced from X-ray photoelectron spectroscopy and X-ray diffraction experiments. An atomistic representation of the ZIF-8/functionalized GO interface was further simulated and carefully analyzed in terms of the nature and the strength of interactions between the two components and the GO conformation with a special emphasis on the impact of the functionalization. It was revealed that grafting the aminopyridine function at the GO significantly enhances the interactions with the terminal functions present at the MOF interface associated with an in-depth penetration of the functionalized GO into the pockets of the ZIF-8. The so-predicted high compatibility between the two components was then supported by Infrared experiments collected on the prepared composite. Complementary transmission electron microscopy experiments further revealed a homogeneous dispersion of the ZIF-8 nanoparticles into the GO matrix with the absence of MOF agglomeration and mechanical testing evidenced a significant enhancement of the tensile strength for the corresponding composite. This fundamental exploration unambiguously demonstrates the key role played by the GO functionalization to achieve optimal interfacial MOF/GO properties, and this opens promising perspectives for processing thin films required for future applications.
The purpose of this study is to develop an alternate in-air input device which is intended to make interaction with computers easier for amputees. This paper proposes the design and utility of accelerometer controlled Myoelectric Human Computer Interface (HCI). This device can function as a PC mouse. The two dimensional position control of the mouse cursor is done by an accelerometer-based method. The left click and right click and other extra functions of this device are controlled by the Electromyographic (EMG) signals. Artificial Neural Networks (ANNs) are used to decode the intended movements during run-time. ANN is a pattern recognition based classification. An amputee can control it using phantom wrist gestures or finger movements.
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