ACS Nano

Publisher: American Chemical Society, American Chemical Society

Journal description

Current impact factor: 12.03

Impact Factor Rankings

2015 Impact Factor Available summer 2015
2013 / 2014 Impact Factor 12.033
2012 Impact Factor 12.062
2011 Impact Factor 10.774
2010 Impact Factor 9.855
2009 Impact Factor 7.493
2008 Impact Factor 5.472

Impact factor over time

Impact factor

Additional details

5-year impact 12.52
Cited half-life 2.40
Immediacy index 1.94
Eigenfactor 0.20
Article influence 4.01
Other titles ACS nano (Online), ACS nano, American Chemical Society nano
ISSN 1936-086X
OCLC 85374429
Material type Document, Periodical, Internet resource
Document type Internet Resource, Computer File, Journal / Magazine / Newspaper

Publisher details

American Chemical Society

  • Pre-print
    • Author cannot archive a pre-print version
  • Restrictions
    • Must obtain written permission from Editor
    • Must not violate ACS ethical Guidelines
  • Post-print
    • Author cannot archive a post-print version
  • Restrictions
    • If mandated by funding agency or employer/ institution
    • If mandated to deposit before 12 months, must obtain waiver from Institution/Funding agency or use AuthorChoice
    • 12 months embargo
  • Conditions
    • On author's personal website, pre-print servers, institutional website, institutional repositories or subject repositories
    • Non-Commercial
    • Must be accompanied by set statement (see policy)
    • Must link to publisher version
    • Publisher's version/PDF cannot be used
    • If mandated sooner than 12 months, must obtain waiver from Editors or use AuthorChoice
    • Reviewed on 07/08/2014
  • Classification
    ​ white

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: A thin Fe2TiO5 layer was produced on hematite either by evaporating TiCl4 solution on FeOOH or by a simple HF-assisted Ti-treatment of FeOOH, both followed by annealing. The prepared Fe2TiO5-hematite heterostructure showed a significant enhancement in photocurrent density compared to that of the pristine hematite. For example, the sample after HF-assisted Ti-treatment exhibited a significantly enhanced photocurrent of 2.0 mA/cm2 at 1.23 V vs. RHE. Moreover, the performance of the Fe2TiO5-hematite heterostructure can be further improved by coupling with Co-Pi catalysts, achieving a higher photocurrent of 2.6 mA/cm2 at 1.23 V vs. RHE. Synchrotron-based soft X-ray absorption spectroscopy analyses clearly revealed the existence of Fe2TiO5 structure on hematite forming a heterojunction, which reduced the photo-generated hole accumulation and then improved the performance.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01028
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    ABSTRACT: Vertical stacking of two-dimensional (2D) crystals has recently attracted substantial interest due to unique properties and potential applications they can introduce. Little is however known about their microstructure as fabrication of the two-dimensional (2D) heterostructures on a rigid substrate limits one's ability to directly study their atomic and chemical structures using electron microscopy. This study demonstrates a unique approach to create atomically thin freestanding van der Waals heterostructures: WSe2/graphene and MoS2/graphene, as ideal model systems to investigate the nucleation and growth mechanisms in heterostructures. In this study we use transmission electron microscopy (TEM) imaging and diffraction to show epitaxial growth of the freestanding WSe2/graphene heterostructure, while no epitaxy is maintained in the MoS2/graphene heterostructure. Ultra high-resolution aberration-corrected scanning transmission electron microscopy (STEM) shows growth of monolayer WSe2 and MoS2 triangles on graphene membrane and reveals their edge morphology and crystallinity. Photoluminescence (PL) measurements indicate a significant quenching of the photoluminescence response for the transition metal dichalcogenides (TMDs) on freestanding graphene, compared to those on a rigid substrate, i.e. sapphire and epitaxial graphene (EG). Using a combination of (S)TEM imaging and electron diffraction analysis, this study also reveals the significant role of defects on the heterostructure growth. The direct growth technique applied here enables us to investigate the heterostructure nucleation and growth mechanisms at the atomic level without sample handling and transfer. Importantly, this approach can be utilized to study a wide spectrum of van der Waals heterostructures.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01677
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    ABSTRACT: Occult nodal metastases increase the risk of cancer recurrence, demoting prognosis and quality of life of patients. While targeted drug delivery by using systemically administered nanocarriers can potentially control metastatic disease, lymph node metastases have been mainly dealt by locally injecting nanocarriers, which may not always be applicable. Herein, we demonstrated that sub-50 nm polymeric micelles incorporating platinum anticancer drugs could target lymph node metastases in a syngeneic melanoma model after systemic injection, even after removing the primary tumors, limiting the growth of the metastases. By comparing these micelles with clinically used doxorubicin-loaded liposomes (Doxil) having 80-nm, as well as a 70-nm version of the micelles, we found that the targeting efficiency of the nanocarriers against lymph node metastases was associated with their size-regulated abilities to extravasate from the blood vasculature in metastases and to penetrate within the metastatic mass. These findings indicate the potential of sub-50 nm polymeric micelles for developing effective conservative treatments against lymph node metastasis capable of reducing relapse and improving survival.
    ACS Nano 04/2015; DOI:10.1021/nn5070259
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    ABSTRACT: Colloidal quantum dots are an attractive thin-film material for photovoltaic applications due to low material costs, ease of fabrication and size-tunable bandgap. Unfortunately, today they suffer from a compromise between light absorption and photocarrier extraction, a fact that currently prevents the complete harvest of incoming above-bandgap solar photons. We have investigated the use of structured substrates and/or electrodes to increase the effective light path through the active material and found that these designs require highly conformal application of the light-absorbing films to achieve the greatest enhancement. This conformality requirement derives from the need for maximal absorption enhancement combined with shortest-distance charge transport. Here we report on a means of processing highly conformal layer-by-layer deposited CQD absorber films onto microstructured, light-recycling electrodes. Specifically, we engineer surface hydrophilicity to achieve conformal deposition of upper layers atop underlying ones. We show that only with the application of conformal coating can we achieve optimal quantum efficiency and enhanced power conversion efficiency in structured-electrode CQD cells.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01296
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    ABSTRACT: One of the potential applications of DNA nanotechnology is the construction of two- or three-dimensional nanostructures that mimic the function of existing biological molecules. In this issue of ACS Nano, Kocabey et al. demonstrate that lipid-bilayer-anchored DNA origami structures can be assembled into prescribed superstructures in a programmed manner. The reported DNA-based artificial system can mimic the dynamic assembly of membrane-associated protein clusters that play an essential role in deformation of cellular membranes.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01723
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    ABSTRACT: We present an immobilization-free and enzyme-free electrochemical nucleic acid sensing strategy, which uses kinetically controlled dendritic assembly of DNA and peptide nucleic acid (PNA). In the presence of a target sequence, ferrocene-labeled PNA probes (Fc-PNAs) and specially designed DNA strands are autonomously assembled into dendritic nanostructures through a cascade of toehold-mediated strand displacement reactions. The consumption of freely diffusible Fc-PNAs (neutrally charged), due to incorporation to DNA/PNA dendrimer, results in a significant electrochemical signal reduction of Fc on a negatively charged electrode from which the hyperbranched and negatively charged dendrimer of DNA/PNA would be electrostatically repelled. The cascade-like assembly process and large electrostatic affinity difference between Fc-PNAs and DNA/PNA dendrimer toward the sensing electrode offer a detection limit down to 100 fM and an inherently high specificity for detecting single nucleotide polymorphisms. The target-triggered mechanism was examined by PAGE analysis, and morphologies of the assembled dendrimers were verified by AFM imaging.
    ACS Nano 04/2015; DOI:10.1021/nn507282f
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    ABSTRACT: Using in-situ surface sensitive electron microscopy performed in real time, we show that the dynamics of micron sized Ga droplets on GaP(111) can be manipulated locally using Au nanoparticles. Detailed measurements of structure and dynamics of the surface from microns to atomic scale are done using both surface electron and scanning probe microscopy. Imaging is done simultaneously on areas with and without Au particles and on samples spanning an order of magnitude in particle coverages. Based on this, we establish the equations of motion that can generally describe the Ga droplet dynamics taking into account three general features: The affinity of Ga droplets to cover steps and rough structures on the surface, the evaporation driven transition of the surface nanoscale morphology from rough to flat, and the enhanced evaporation due to Ga droplets and Au nanoparticles. Separately these features can induce either self-propelled random motion or directional motion, but in combination the self-propelled motion acts to increase the directional motion even if the directional force is 100 times weaker than the random force. We then find that the Au particles initiate a faster native oxide desorption and speeds up the rough to flat surface transition in their vicinity. This changes the balance of forces on the Ga droplets near the Au particles effectively deflecting the droplets from these areas. The model is experimentally verified for the present materials system, but due to its very general assumptions it could also be relevant for the many other materials systems that display self-propelled random motion.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01228
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    ABSTRACT: We examine the temperature dependence of graphene edge terminations at the atomic scale using an in situ heating holder within an aberration-corrected transmission electron microscope. The relative ratios of armchair, zigzag, and reconstructed zigzag edges from over 350 frames at each temperature are measured. Below 400 °C, the edges are dominated by zigzag terminations, but above 600 °C, this changes dramatically, with edges dominated by armchair and reconstructed zigzag edges. We show that at low temperature chemical etching effects dominate and cause deviation to the thermodynamics of the system. At high temperatures (600 and 800 °C), adsorbates are evaporated from the surface of graphene and chemical etching effects are significantly reduced, enabling the thermodynamic distribution of edge types to be observed. The growth rate of holes at high temperature is also shown to be slower than at room temperature, indicative of the reduced chemical etching process. These results provide important insights into the role of chemical etching effects in the hole formation, edge sputtering, and edge reconstruction in graphene.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01130
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    ABSTRACT: This paper reports Seebeck effects driven by both surface polarization difference and entropy difference by using photoinduced intramolecular charge-transfer states in n-type and p-type conjugated polymers, namely IIDT and IIDDT, respectively, based on vertical conductor/polymer/conductor thin-film devices. We obtain large Seebeck coefficients of -898 μV/K from n-type IIDT and 1300 μV/K from p-type IIDDT when the charge-transfer states are generated by a white light illumination of 100 mW/cm², compared with the values of 380 μV/K and 470 μV/K in dark conditions, respectively. Simultaneously, the electrical conductivities are increased from almost insulating states in dark condition to conducting states under photoexcitation in both n-type IIDT and p-type IIDDT based devices. The large Seebeck effects can be attributed to the following two mechanisms. Firstly, the intramolecular charge-transfer states exhibit strong electron-phonon coupling, which leads to a polarization difference between high and low temperature surfaces. This polarization difference provides an additional driving force to diffuse the charge carriers for the development of Seebeck effects under a temperature gradient. Secondly, the intramolecular charge-transfer states generate majority electrons or holes in the n-type IIDT or p-type IIDDT, ready to be diffused between high and low temperature surfaces for development of the Seebeck effects. Based on surface polarization difference together with entropy difference the intramolecular charge-transfer states can largely enhance the Seebeck effects in the n-type IIDT and p-type IIDDT devices. Furthermore, we find that the Seebeck effects can shift between polarization and entropy regimes when the electrical conductivities are changed by photoexcitation. Therefore, using intramolecular charge-transfer states presents an approach to develop thermoelectric effects in organic materials based on vertical conductor/polymer/conductor thin-film devices.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b00589
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    ABSTRACT: Transition metal dichalcogenides are relevant for electronic devices owing to their sizable band gaps and absence of dangling bonds on their surfaces. For device development, a controllable method for doping these materials is essential. In this paper, we demonstrate an electrostatic gating method using a solid polymer electrolyte, polyethylene oxide and CsClO4, on exfoliated multilayer 2H-MoTe2. The electrolyte enables the device to be efficiently reconfigured between n- and p channel operation with ON/OFF ratios of approximately 5 decades. Sheet carrier densities as high as 1.6×1013 cm-2 can be achieved because of a large electric double layer capacitance (measured as 4 μF/cm2). Further, we show that an in-plane electric field can be used to establish a cation/anion transition region between source and drain, forming a p-n junction in the 2H-MoTe2 channel. This junction is locked in place by decreasing the temperature of the device below the glass transition temperature of the electrolyte. The ideality factor of the p-n junction is 2.3, suggesting that the junction is recombination dominated.
    ACS Nano 04/2015; DOI:10.1021/nn506521p
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    ABSTRACT: Although great progress in the synthesis of porous networks of metal and metal oxide nanoparticles with highly accessible pore surface and ordered mesoscale pores has been achieved, synthesis of assembled 3D mesostructures of metal-chalcogenide nanocrystals is still challenging. In this work we demonstrate that ordered mesoporous networks, which comprise well-defined interconnected metal sulfide nanocrystals, can be prepared through a polymer-templated oxidative polymerization process. The resulting self-assembled mesostructures that were obtained after solvent extraction of the polymer template impart the unique combination of light-emitting metal chalcogenide nanocrystals, three-dimensional open-pore structure, high surface area, and uniform pores. We show that the pore surface of these materials is active and accessible to incoming molecules, exhibiting high photocatalytic activity and stability, for instance, in oxidation of 1-phenylethanol into acetophenone. We demonstrate through appropriate selection of the synthetic components that this method is general to prepare ordered mesoporous materials from metal chalcogenide nanocrystals with various sizes and compositions.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01014
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    ABSTRACT: The interfacial shear strength between Si microwires and a Nafion membrane has been tailored through surface functionalization of the Si. Acidic (-COOH terminated) or basic (-NH2-terminated) surface-bound functionality was introduced by hydrosilylation reactions to probe the interactions between the functionalized Si microwires and hydrophilic, ionically charged sites in the Nafion polymeric side chains. Surfaces functionalized with SiOx, Si-H or Si-CH3 were also synthesized and investigated. The interfacial shear strength between the functionalized Si microwire surfaces and the Nafion matrix was quantified by uniaxial wire pull-out experiments in an in situ nanomechanical instrument that allowed simultaneous collection of mechanical data and visualization of the deformation process. In this process, an axial load was applied to the custom-shaped top portions of individual wires until debonding occurred from the Nafion matrix. The shear strength obtained from the nanomechanical measurements correlated with the chemical bond strength and the functionalization density of the molecular layer, with values ranging from 7 MPa for Si-CH3 surfaces to ~16-20 MPa for oxygen-containing surface functionalities. Hence surface chemical control can be used to influence the mechanical adhesion forces at a Si-Nafion interface.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b00468
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    ABSTRACT: Nickel (II) oxide (NiO) is an important wide gap p-type semiconductor used as a hole transport material for dye sensitized solar cells and as a water oxidation electrocatalyst. Here we demonstrate that nanocrystals of the material have increased p-type character and improved photocatalytic activity for hydrogen evolution from water in the presence of methanol as sacrificial electron donor. NiO nanocrystals were synthesized by hydrolysis of Ni(II) nitrate under hydrothermal conditions followed by calcination in air. The crystals have the rock salt structure type and adopt a plate-like morphology (50-90 nm x 10-15 nm). Diffuse reflectance absorbance spectra indicate a band gap of 3.45 eV, similar to bulk NiO. Photoelectrochemical measurements at neutral pH with methylviologen as electron acceptor photo-onset potentials (Fermi energies) of 0.2 eV and 0.05 eV (NHE) for nanoscale and bulk NiO respectively. Nano-NiO and NiO-Pt composites obtained by photodepositon of H2PtCl6 catalyze hydrogen evolution from aqueous methanol at rates of 0.8 and 4.5 μmol H2 h-1, respectively, compared to 0.5 and 2.1 μmol H2 h-1 for bulk-NiO and NiO-Pt (20 mg of catalyst, 300 W Xe lamp). Surface photovoltage spectroscopy of NiO and Ni-Pt films on Au substrates, indicate a metal Pt-NiO junction with 30 mV photovoltage that promotes carrier separation. The increased photocatalytic and photoelectrochemical performance of nano-NiO is due to improved minority carrier extraction and increased p-type character, as deduced from Mott Schottky plots, optical absorbance, and X-ray photoelectron spectroscopy data.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b00435
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    ABSTRACT: In this contribution we demonstrate the effective separation of single-wall carbon nanotube (SWCNT) species with diameters larger than 1 nm through multi-stage aqueous two phase extraction (ATPE), including isolation at the near-monochiral species level up to at least the diameter range of SWCNTs synthesized by electric arc synthesis (1.3 nm - 1.6 nm). We also demonstrate that refined species are readily obtained from both the metallic and semiconducting sub-populations of SWCNTs, and that this methodology is effective for multiple SWCNT raw materials. Using this data, we report an empirical function for the necessary surfactant concentrations in the ATPE method for separating different SWCNTs into either the lower or upper phase as a function of SWCNT diameter. This empirical correlation enables predictive separation design, and identifies a subset of SWCNTs that behave unusually as compared to other species. These results not only dramatically increase the range of SWCNT diameters to which species selective separation can be achieved, but also demonstrate that aqueous two-phase separations can be designed across experimentally accessible ranges of surfactant concentrations to controllably separate SWCNT populations of very small (~ 0.62 nm) to very large diameters (> 1.7 nm). Together, the results reported here indicate that total separation of all SWCNT species is likely feasible by the ATPE method, especially given future development of multistage automated extraction techniques.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01123
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    ABSTRACT: We report the synthesis of centimeter-scale monolayer WS2 on gold foil by chemical vapor deposition. The limited tungsten and sulfur solubility in gold foil allows monolayer WS2 film growth on gold surface. To ensure the coverage uniformity of monolayer WS2 film, the tungsten source-coated substrate was placed in parallel with Au foil under hydrogen sulfide atmosphere. The high growth temperature near 935 oC helps to increase a domain size up to 420 μm. Gold foil is reused for the repeatable growth after bubbling transfer. The WS2-based field effect transistor reveals an electron mobility of 20 cm2 V-1 s-1 with high on-off ratio of ~108 at room temperature, which is the highest reported value from previous reports of CVD-grown WS2 samples. The on-off ratio of integrated multiple FETs on the large area WS2 film on SiO2 (300 nm)/Si substrate shows within the same order, implying reasonable uniformity of WS2 FET device characteristics over a large area of 3 x 1.5 cm2.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01529
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    ABSTRACT: To monitor dynamic volume changes of electrode materials during electrochemical lithium storage and removal process is of utmost importance for developing high performance lithium storage materials. We herein report an in operando probing of mesoscopic structural changes in ordered mesoporous electrode materials during cycling with synchrotron-based small angel X-ray scattering (SAXS) technique. In operando SAXS studies combined with electrochemical and other physical characterizations straightforwardly show how porous electrode materials underwent volume changes during the whole process of charge and discharge, with respect to their own reaction mechanism with lithium. This comprehensive information on the pore dynamics as well as volume changes of the electrode materials will not only be critical in further understanding of lithium ion storage reaction mechanism of materials, but also enable the innovative design of high performance nanostructured materials for next generation batteries.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01378
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    ABSTRACT: Monolayers of group VI transition metal dichalcogenides possess direct gaps in the visible spectrum with the exception of MoTe2 where its gap is suitably located in the infrared region but its stability is of particular as tellurium compounds are acutely sensitive to oxygen exposure. Here, our environmental (time dependent) measurements reveal two distinct effects on MoTe2 monolayers: For weakly luminescent monolayers, photoluminescence signal and optical contrast disappear, as if they are decomposed, but yet remain intact as evidenced by AFM and Raman measurements. In contrast, strongly luminescent monolayers retain their optical contrast for prolong amount of time while their PL peak blue-shifts and PL intensity saturates to slightly lower values. Our x-ray photoelectron spectroscopy measurements and DFT calculations suggest that the presence of defects and functionalization of these defect sites with O2 molecules strongly dictate their material properties and aging response by changing the excitonic dynamics due to deep or shallow states that are created within the optical band gap. Presented results not only shed light on environmental effects on fundamental material properties and excitonic dynamics of MoTe2 monolayers but also highlight striking material transformation for metastable 2D systems such as WTe2, silicone, and phosphorene.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b00985
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    ABSTRACT: Structural defects strongly impact the electrical transport properties of graphene nanostructures. In this Perspective, we give a brief overview of different types of defects in graphene and their effect on transport properties. We discuss recent experimental progress on graphene self-repair of defects, with a focus on in situ transmission electron microscopy studies. Finally, we present the outlook for graphene self-repair and in situ experiments.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b01762
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    ABSTRACT: We report mesoporous composite materials (m-GeO2, m-GeO2/C and m-Ge-GeO2/C) with large pore size which are synthesized by a simple block copolymer directed self-assembly. m-Ge/GeO2/C shows greatly enhanced coulombic efficiency, high reversible capacity (1631 mA h g-1) and stable cycle life compared with the other mesoporous and bulk GeO2 electrodes. m-Ge/GeO2/C exhibits one of the highest areal capacities (1.65 mA h cm-2) among previously reported Ge and GeO2-based anodes. The superior electrochemical performance in m-Ge/GeO2/C arises from the highly improved kinetics of conversion reaction due to the synergistic effects of the mesoporous structures and the conductive carbon and metallic Ge.
    ACS Nano 04/2015; DOI:10.1021/acsnano.5b00817