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1.
ACS Nano ; 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-32031783

RESUMO

In recent years, two-dimensional (2D) group VA elemental materials have attracted considerable interest from physics/chemistry and materials science communities, with particular attention paid to honeycomb blue phosphorene. To date, phosphorene is limited to its α-phase and small sizes because it can only be produced by exfoliating black phosphorus crystals. Here, we report the direct synthesis of high-quality phosphorene on a nonmetallic copper oxide substrate by molecular beam epitaxy. By combining scanning tunneling microscopy/spectroscopy, X-ray photoelectron spectroscopy, and first-principles calculations, we demonstrate the growth intermediates and electronic structures of phosphorene on Cu3O2/Cu(111). Surprisingly, the grown phosphorene has a flat honeycomb lattice, similar to graphene, which exhibits a metallic nature. We reveal that the growth mechanism and morphology of phosphorene are strongly correlated with the surface structures of prepared copper oxide, and the resulting phosphorene can be stabilized after high-temperature annealing above 600 K even in oxygen gas. The high stability is closely related to the irregular Moiré pattern and structural corrugations of phosphorene on Cu3O2/Cu(111) that efficiently relieve the surface strain. These results shed light on future fabrication of large-scale, versatile 2D structures for interconnect and device integration.

2.
Nanoscale ; 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32091058

RESUMO

A key challenge for the fabrication of flexible electrochemical capacitors is to prepare robust electrode materials with excellent integration of high specific capacitances and superior mechanical properties. Aramid nanofibers (ANFs) are emerging candidates for constructing flexible electrode materials due to their superior mechanical properties. However, the present ANF based electrode materials are generally designed by mixing ANFs with electrochemically active components, which results in an unfavorable trade-off in mechanical and electrochemical properties. In this work, we reported flexible, mechanically strong, and free-standing supercapacitor electrodes based on polyaniline (PANI) nanostructure functionalized ANF films for the first time. The flexible PANI@ANF film electrodes achieved an efficient combination of mechanical and electrochemical performance in a single platform with a specific capacitance of 441.0 F g-1 at a current density of 1 A g-1 and a tensile strength of 233.3 MPa, respectively. This kind of free-standing electrode material may have great potential in the development of flexible energy-storage devices. Furthermore, we anticipate that this study may provide insight into the functionalization of aramid nanofiber-based materials for structural energy and power systems with high mechanical performance.

3.
J Phys Chem Lett ; : 1317-1329, 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-31945298

RESUMO

An atomic layer of tin in a buckled honeycomb lattice, termed stanene, is a promising large-gap two-dimensional topological insulator for realizing room-temperature quantum-spin-Hall effect and therefore has drawn tremendous interest in recent years. Because the electronic structures of Sn allotropes are sensitive to lattice strain, e.g. the semimetallic α-phase of Sn can transform into a three-dimensional topological Dirac semimetal under compressive strain, recent experimental advances have demonstrated that stanene layers on different substrates can also host various electronic properties relating to in-plane strain, interfacial charge transfer, layer thickness, and so on. Thus, comprehensive understanding of the growth mechanism at the atomic scale is highly desirable for precise control of such tunable properties. Herein, the fundamental properties of stanene and α-Sn films, recent achievements in epitaxial growth, challenges in high-quality synthesis, and possible applications of stanene are discussed.

4.
Phys Chem Chem Phys ; 22(3): 1097-1106, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31894789

RESUMO

Supported ionic liquids (ILs) are attractive alternatives for CO2 capture and the thickness of supported IL films plays a critical role in the CO2 mass transfer rate. However, the dependence of CO2 uptake on the IL film thickness differs as the system varies. In this work, atomic force microscopy (AFM) is employed to probe the 'nanofriction coefficient' to characterize the mobility of ILs at the solid interface, in which, the smaller the nanofriction coefficient, the faster are the ionic mobility and CO2 mass transfer. A monotonic and almost linear relationship for supported IL films is obtained between the resistance of CO2 mass transfer (1/k) and the nanofriction coefficient (µ), avoiding the controversy over the effect of supported IL film thickness on CO2 adsorption. The enhanced mass transfer of CO2 adsorption at IL-solid interfaces is observed at smaller resistance 1/k and friction coefficient µ. The low-friction driven local mobility (diffusion) of ILs at solid interfaces is enhanced, promoting the exchange mixing of the ILs adsorbing CO2 with the 'blank-clean' ions of the ILs, and thus accelerating the CO2 mass transfer. The proposed correlation links the nanoscale friction with the mass transfer of CO2 adsorption, providing a fresh view on the design of ultra-low frictional supported ILs for enhanced CO2 capture and separation processes.

5.
J Nanosci Nanotechnol ; 20(6): 3588-3597, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31748056

RESUMO

Imidazolium-based poly(ionic liquid)s were synthesized and used as sensing film for the adsorption of volatile organic compounds. Based on a quartz crystal microbalance system, the sensing properties of the imidazolium-based poly(ionic liquid)s on volatile organic compounds was assessed according to the position of imidazolium cation in the polymer chain (the main-chain or side-chain type) and the varied counterions. The results indicated that the imidazolium-based poly(ionic liquid)s films have much higher adsorption capability on volatile organic acids than other volatile organic compounds, which is due to the strong affinity between imidazolium group and the carboxyl group. The position of imidazolium cation in the polymer chain and counterions of the imidazolium-based poly(ionic liquid)s was found to be able to influence the selectivity and sensitivity of volatile organic acids. The main-chain imidazolium-based poly(ionic liquid)s were shown strengthen the adsorption of propionic acid vapor, while the counter ion of dicyanamide showed the highest selectivity on volatile organic acids. Based on the quartz crystal microbalance sensing system, the imidazoliumbased poly(ionic liquid)s film was shown capable of detecting volatile organic acids with a theoretical detection limit of about 3.1 ppb and a quick recovery time less than 40 seconds. The sensing performance is also stable for repeated usage and after long-time storage.

6.
ACS Nano ; 13(12): 14005-14012, 2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31794176

RESUMO

We report the production of fullerene microtubes (FMTs), having solid cores bisecting their tubular cavities, from solutions of mixtures of fullerene C60 and C70 and have demonstrated the structural transformation of FMTs to fullerene microhorns (FMHs) upon their exposure to alcohol/mesitylene mixtures at 25 °C. The conically shaped microhorns have hollow interiors and exhibit preferential recognition of silica particles over fullerene C70, polystyrene (PS) latex, PS hydroxylate, or PS carboxylate particles of similar dimensions due to strong electrostatic interactions between negatively charged FMHs and positively charged silica particles.

7.
ACS Nano ; 13(9): 10622-10630, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31487147

RESUMO

Epitaxial two-dimensional (2D) nanostructures with regular patterns show great promise as templates for adsorbate confinement. Prospectively, employing 2D semiconductors with reduced density of states leads to a long excited-state lifetime that allows us to directly image the dynamics of the adsorbate. We show that epitaxial blue phosphorene (blueP) on Au(111) provides such a platform to trap water molecules in the periodic nanopores without formation of strong bonds. The trapped water aggregate is tentatively assigned to a hexamer based on our scanning tunneling microscopy studies and first-principles calculations. Real-space observation of conformational switching of the hexamer induced by inelastic electrons is achieved by using low-temperature scanning tunneling microscopy with molecular resolution. We found a localized interfacial charge rearrangement between the water hexamer and P atoms underneath that is responsible for the reversible desorption and adsorption of water molecules by changing the sample bias polarity from positive to negative, offering a promising strategy for engineering the electronic properties of blueP.

8.
ACS Appl Mater Interfaces ; 11(20): 18053-18061, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-30964981

RESUMO

The controlled assembly of metal nanoparticles into ordered structures interacting with biological molecules is an emerging concept in surface science. Here, bare magnetite nanoparticles (Fe3O4-NPs) were employed as nanoadhesives to capture hollow metallic nanostructures (Au-Ag nanocages) from aqueous suspensions, and these coupled nanostructures were patterned onto various types of substrate via magnetolithography. Microwires of Au-Ag nanocages patterned onto an Au substrate behaved as optical antennas, providing a plasmonic enhancement exploited in surface-enhanced infrared absorption spectroscopy (SEIRAS) to investigate the proteins cytochrome c, bilirubin oxidase, alcohol dehydrogenase, bovine serum albumin, and glucose oxidase. Chemical maps containing more than 4000 spectra, acquired within only 2 min with a focal plane array detector, indicate that proteins were adsorbed along the microwires with their secondary structure preserved according to the spatial distribution of their amide groups. We believe there are significant practical aspects of the methodology proposed here to develop an alternative label-free assay for investigating biological molecules.


Assuntos
Ouro/química , Nanopartículas de Magnetita/química , Oxirredutases/química , Soroalbumina Bovina/química , Prata/química , Animais , Bovinos , Nanopartículas , Espectrofotometria Infravermelho
9.
Phys Chem Chem Phys ; 20(27): 18873-18878, 2018 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-29968876

RESUMO

A hierarchical heterostructure composed of silver nanoparticles (Ag-NPs: average diameter ∼10 nm) on fullerene nanorods (FNRs: average length ∼11 µm and average diameter ∼200 nm) was fabricated using a simple solution route. It was used as an effective single particle freestanding surface enhanced Raman scattering (SERS) substrate for the detection of target molecules (Rhodamine 6G: R6G). FNRs were formed ultra-rapidly (formation process completed in a few seconds) at a liquid-liquid interface of methanol and C60/mesitylene solution then Ag-NPs were grown directly on the surfaces of the FNRs by treatment with a solution of silver nitrate in ethanol. This unique hierarchical heterostructure allows efficient adsorption of target molecules also acting as an effective SERS substrate capable of detecting the adsorbed R6G molecules in the nanomolar concentration range. In this study, SERS spectra are acquired on an isolated single Ag-FNR for the detection of the absorbed molecule rather than from a bulk, large area film composed of silver/gold nanoparticles as used in conventional methods. Thus, this work provides a new approach for the design and fabrication of freestanding SERS substrates for molecular detection applications.

10.
Chem Commun (Camb) ; 54(56): 7822-7825, 2018 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-29947371

RESUMO

The induced-fit accommodation of a variety of gaseous molecules including non-polar molecules has been demonstrated in porphyrin-based supramolecular architectures for the first time. Moreover, the gas uptake behaviour can be modulated by changing the central cation of porphyrin.

11.
ACS Appl Mater Interfaces ; 9(51): 44458-44465, 2017 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-29210263

RESUMO

Fullerene C60 microbelts were fabricated using the liquid-liquid interfacial precipitation method and converted into quasi 2D mesoporous carbon microbelts by heat treatment at elevated temperatures of 900 and 2000 °C. The carbon microbelts obtained by heat treatment of fullerene C60 microbelts at 900 °C showed excellent electrochemical supercapacitive performance, exhibiting high specific capacitances ca. 360 F g-1 (at 5 mV s-1) and 290 F g-1 (at 1 A g-1) because of the enhanced surface area and the robust mesoporous framework structure. Additionally, the heat-treated carbon microbelt showed good rate performance, retaining 49% of capacitance at a high scan rate of 10 A g-1. The carbon belts exhibit super cyclic stability. Capacity loss was not observed even after 10 000 charge/discharge cycles. These results demonstrate that the quasi 2D mesoporous carbon microbelts derived from a π-electron-rich carbon source, fullerene C60 crystals, could be used as a new candidate material for electrochemical supercapacitor applications.

12.
Phys Chem Chem Phys ; 19(43): 29099-29105, 2017 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-29075701

RESUMO

Polycyclic aromatic compounds (naphthalene, anthracene and pyrene) have been intercalated into the superstructures of fullerene nanowhiskers, using a facile liquid-liquid interfacial precipitation (LLIP) method. Due to the interaction between polycyclic molecules and fullerene, the growth of fullerene crystals was interfered in comparison to the fullerene crystal growth without the polycyclic molecules, resulting in the formation of fullerene superstructures with various nanofeatures. Moreover, the fluorescence emissions of the fullerene superstructures were significantly changed due to the intercalation of the polycyclic molecules, implying the influence of molecular packing on the electron transfer within the nanostructures. These results may bring new insights on the control of fullerene nanostructures and to manipulate their optical properties in optoelectronic devices.

13.
Adv Mater ; 29(42)2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28961349

RESUMO

Creating well-ordered nanoporosity in biomolecules promises stability and activity, offering access to an even wider range of application possibilities. Here, the preparation of nanoporous protein films containing cytochrome c protein molecules is reported through a soft-templating strategy using polystyrene (PS) spheres of different sizes as templates. The stability of the cytochrome c film is demonstrated through electrochemistry studies to show a reusable nature of these films over a long period of time. The size of the PS spheres is varied to tune the pore diameter and the thickness of the cytochrome c films, which are quite stable and highly selective for sensing toxic acidic vapors. The fusion of the templating strategy and the self-assembly of biomolecules may offer various possibilities by generating a new series of porous biomolecules including enzymes with different molecular weights and diameters, peptides, antibodies, and DNA with interesting catalytic, adsorption, sensing, and electronic properties.

14.
ACS Appl Mater Interfaces ; 9(37): 32054-32064, 2017 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-28853856

RESUMO

The recent booming development of wearable electronics urgently calls for high-performance flexible strain sensors. To date, it is still a challenge to manufacture flexible strain sensors with superb sensitivity and a large workable strain range simultaneously. Herein, a facile, quick, cost-effective, and scalable strategy is adopted to fabricate novel strain sensors based on reduced graphene oxide woven fabrics (GWF). By pyrolyzing commercial cotton bandages coated with graphene oxide (GO) sheets in an ethanol flame, the reduction of GO and the pyrolysis of the cotton bandage template can be synchronously completed in tens of seconds. Due to the unique hierarchical structure of the GWF, the strain sensor based on GWF exhibits large stretchability (57% strain) with high sensitivity, inconspicuous drift, and durability. The GWF strain sensor is successfully used to monitor full-range (both subtle and vigorous) human activities or physical vibrational signals of the local environment. The present work offers an effective strategy to rapidly prepare low-cost flexible strain sensors with potential applications in the fields of wearable electronics, artificial intelligence devices, and so forth.

15.
Langmuir ; 33(42): 11590-11602, 2017 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-28830141

RESUMO

We have infused graphene/ionic liquid into block copolymer homoporous membranes (HOMEs), which have highly ordered uniform cylindrical nanopores, to form compact, dense, and continuous graphene/ionic liquid (Gr/IL) lubricating layers at interfaces, enabling a reduction in the friction coefficient. Raman and XPS analyses, confirmed the parallel alignment of the cation of ILs on graphene by the π-π stacking interaction of the imidazolium ring with the graphene layer. This alignment loosens the lattice spacing of Gr in Gr/ILs, leading to a larger lattice spacing of 0.36 nm in Gr of Gr/ILs hybrids than the pristine Gr (0.33 nm). The loose graphene layers, which are caused by the coexistence of graphene and ILs, would make the sliding easier, and favor the lubrication. An increase in the friction coefficient was observed on ILs-infused block copolymer HOMEs, as compared to Gr/ILs-infused ones, due to the absence of Gr and the unstably formed ILs film. Gr/ILs-infused block copolymer HOMEs also exhibit much smaller residual indentation depth and peak indentation depth in comparison with ILs-infused ones. This indicates that the existence of stably supported Gr/ILs hybrid liquid films aids the reduction of the friction coefficient by preventing the thinning of the lubricant layer and exposure of the underlying block copolymer HOMEs.

16.
ACS Appl Mater Interfaces ; 9(11): 9945-9954, 2017 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-28234457

RESUMO

The development of novel functional nanomaterials is critically important for the further evolution of advanced chemical sensor technology. For this purpose, metalloporphyrins offer unique binding properties as host molecules that can be tailored at the synthetic level and potentially improved by incorporation into inorganic materials. In this work, we present a novel hybrid nanosystem based on a highly networked silica nanoarchitecture conjugated through covalent bonding to an organic functional molecule, a tetraphenylporphyrin derivative, and its metal complexes. The sensing properties of the new hybrid materials were studied using a nanomechanical membrane-type surface stress sensor (MSS) with acetone and nitric oxide as model analytes. This hybrid inorganic-organic MSS-based system exhibited excellent performance for acetone sensing at low operating temperatures (37 °C), making it available for diagnostic monitoring. The hybridization of an inorganic substrate of large surface area with organic molecules of various functionalities results in sub-ppm detection of acetone vapors. Acetone is an important metabolite in lipid metabolism and can also be present in industrial environments at deleterious levels. Therefore, we believe that the analysis system presented by our work represents an excellent opportunity for the development of a portable, easy-to-use device for monitoring local acetone levels.

17.
J Am Chem Soc ; 139(10): 3669-3675, 2017 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-28186738

RESUMO

Intermolecular C-C coupling after cleavage of C-X (mostly, X = Br or I) bonds has been extensively studied for facilitating the synthesis of polymeric nanostructures. However, the accidental appearance of C-H coupling at the terminal carbon atoms would limit the successive extension of covalent polymers. To our knowledge, the selective C-H coupling after dehalogenation has not so far been reported, which may illuminate another interesting field of chemical synthesis on surfaces besides in situ fabrication of polymers, i.e., synthesis of novel organic molecules. By combining STM imaging, XPS analysis, and DFT calculations, we have achieved predominant C-C coupling on Au(111) and more interestingly selective C-H coupling on Ag(111), which in turn leads to selective synthesis of polymeric chains or new organic molecules.

18.
Sci Rep ; 7: 41773, 2017 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-28155906

RESUMO

Particle sintering is one of the most significant impediments to functional nanoparticles in many valuable applications especially catalysis. Herein, we report that sintering-resistant nanoparticle systems can be realized through a simple materials-design which maximizes the particle-to-particle traveling distance of neighbouring nanoparticles. As a demonstration, Pt nanoparticles were placed apart from each other in wide-mouthed compartments tailored on the surface of self-assembled silica nanosheets. These Pt nanoparticles retained their particle size after calcination at elevated temperatures because the compartment wall elongates the particle-to-particle traveling distance to preclude the possibility of sintering. Moreover, these Pt nanoparticles in wide-mouthed compartments were fully accessible to the environment and exhibited much higher catalytic activity for CO oxidation than the nanoparticles confined in the nanochannels of mesoporous silica. The proposed materials-design strategy is applicable not only to industrial catalysts operating in harsh conditions, but also opens up possibilities in developing advanced nanoparticle-based materials with sustained performance.

19.
ACS Appl Mater Interfaces ; 9(5): 4509-4518, 2017 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-28106369

RESUMO

Spongelike porous silica nanosheets, with nanometer thicknesses and pores whose diameters are on the hundreds-of-nanometers scale, have been used as a novel carrier for molecular immobilization of different guests. Enhanced properties of encapsulation were shown for drug molecules of different dimensions due to "softness" caused by the specific nanometric features of the porous structure. The encapsulating effect of the structure results in sustained and stimuli-responsive release behavior of immobilized guest molecules. By studying the adsorption process of DNA molecules on spongelike porous nanosheets or on solid nanoparticles by use of a quartz crystal microbalance, we show that better elasticity of surfaces of the porous nanosheets over that of solid nanoparticles can improve the immobilization of guest molecules. The coating of porous silica nanosheets onto various substrates was also found to effectively mediate DNA delivery to mammalian cells.


Assuntos
Dióxido de Silício/química , Adsorção , Animais , DNA , Nanopartículas , Porosidade
20.
ACS Appl Mater Interfaces ; 8(29): 18922-9, 2016 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-27387017

RESUMO

Silver has been recognized as a broad-spectrum antimicrobial agent and extensively used in biomedical applications. Through a sequential one-pot synthesis strategy, we have successfully incorporated silver into flake-shell nanoparticles. Due to the simultaneous growth of networked nanostructures of silica and in situ reduction of silver ions, homogeneously distributed silver into the shell of the nanocapsule was formed. The antibacterial test indicated that the silver-incorporated silica nanocapsule exhibits effective antibacterial activity, inhibiting the bacterial growth by 75%. In addition, with the encapsulation of other antibiotic agent into the structure, an enhanced antibacterial effect under dual-modality could also be achieved.

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