Read by QxMD icon Read

Journal of Physical Chemistry. C, Nanomaterials and Interfaces

Robin J P Broos, Bart Zijlstra, Ivo A W Filot, Emiel J M Hensen
The first step in the Fischer-Tropsch reaction is the production of C1 monomers by the dissociation of the C-O bond. Although Fe is the active metal, it is well known that under typical reaction conditions, it changes into various carbide phases. The Hägg carbide (χ-Fe5 C2 ) phase is usually considered as the catalytically active phase. We carried out a comprehensive DFT study of CO dissociation on various surface terminations of the Hägg carbide, selected on their specific site topology and the presence of stepped sites...
May 10, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Kai Sotthewes, Özlem Kap, Hairong Wu, Damien Thompson, Jurriaan Huskens, Harold J W Zandvliet
Self-assembled monolayers (SAMs) of alkanethiols on gold are a commonly used platform for nanotechnology owing to their ease of preparation and high surface coverage. Unfortunately, the gold-sulfur bond is oxidized at ambient conditions which alters the stability and structure of the monolayer. We show using scanning tunneling microscopy and X-ray photoelectron spectroscopy that decanethiolate molecules oxidize into decanesulfonates that organize into a hitherto unknown striped phase. Air-exposed SAMs oxidize, as can be determined by a shift of the S 2p peak and the appearance of O 1s photoelectrons as part of the decanethiol monolayer transforms into a lamellae-like decanesulfonate structure when exposed to air...
April 19, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Jin-Xun Liu, Ivo A W Filot, Yaqiong Su, Bart Zijlstra, Emiel J M Hensen
The structure sensitivity of gold-catalyzed CO oxidation is presented by analyzing in detail the dependence of CO oxidation rate on particle size. Clusters with less than 14 gold atoms adopt a planar structure, whereas larger ones adopt a three-dimensional structure. The CO and O2 adsorption properties depend strongly on particle structure and size. All of the reaction barriers relevant to CO oxidation display linear scaling relationships with CO and O2 binding strengths as main reactivity descriptors. Planar and three-dimensional gold clusters exhibit different linear scaling relationship due to different surface topologies and different coordination numbers of the surface atoms...
April 19, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Thomas Häusler, Paul Gebhardt, Daniel Iglesias, Christoph Rameshan, Silvia Marchesan, Dominik Eder, Hinrich Grothe
Aerosols can act as cloud condensation nuclei and/or ice-nucleating particles (INPs), influencing cloud properties. In particular, INPs show a variety of different and complex mechanisms when interacting with water during the freezing process. To gain a fundamental understanding of the heterogeneous freezing mechanisms, studies with proxies for atmospheric INPs must be performed. Graphene and its derivatives offer suitable model systems for soot particles, which are ubiquitous aerosols in the atmosphere. In this work, we present an investigation of the ice nucleation activity (INA) of different types of graphene and graphene oxides...
April 19, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Bernd Kollmann, Zhongrui Chen, Daniel Lüftner, Olivier Siri, Peter Puschnig
We present a combined experimental and theoretical study of electronic and optical properties of dihydro-tetraaza-acenes (DHTA n ). Using solvent-free condensation, we are able to synthesize not only DHTA5 but also the longer DHTA6 and DHTA7 molecules. We then investigate their gas-phase electronic structures by means of ab initio density functional calculations employing an optimally tuned range-separated hybrid functional. By comparing with the parent linear oligoacenes ( n A) and based on computed ionization potentials and electron affinities, we predict DHTA n molecules to be more stable than acenes of the same length, where we expect DHTA n molecules to be persistent at least up to n = 7 rings...
March 22, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
E S Merijn Blaakmeer, Giuseppe Antinucci, Andrea Correa, Vincenzo Busico, Ernst R H van Eck, Arno P M Kentgens
Ziegler-Natta catalysis is a very important industrial process for the production of polyolefins. However, the catalysts are not well-understood at the molecular level. Yet, atomic-scale structural information is of pivotal importance for rational catalyst development. We applied a solid-state NMR/density functional theory tandem approach to gain detailed insight into the interactions between the catalysts' support, MgCl2 , and organic electron donors. Because of the heterogeneity of the samples, large line widths are observed in the carbon spectra...
March 15, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Ibadillah A Digdaya, Bartek J Trześniewski, Gede W P Adhyaksa, Erik C Garnett, Wilson A Smith
Metal-insulator-semiconductor (MIS) photoelectrodes offer a simple alternative to the traditional semiconductor-liquid junction and the conventional p-n junction electrode. Highly efficient MIS photoanodes require interfacial surface passivating oxides and high workfunction metals to produce a high photovoltage. Herein, we investigate and analyze the effect of interfacial oxides and metal workfunctions on the barrier height and the photovoltage of a c-Si photoanode. We use two metal components in a bimetal contact configuration and observe the modulation of the effective barrier height and the resulting photovoltage as a function of the secondary outer metal...
March 15, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Davide Bartesaghi, Adam H Slavney, María C Gélvez-Rueda, Bridget A Connor, Ferdinand C Grozema, Hemamala I Karunadasa, Tom J Savenije
Double perovskites, comprising two different cations, are potential nontoxic alternatives to lead halide perovskites. Here, we characterized thin films and crystals of Cs2 AgBiBr6 by time-resolved microwave conductance (TRMC), which probes formation and decay of mobile charges upon pulsed irradiation. Optical excitation of films results in the formation of charges with a yield times mobility product, φΣμ > 1 cm2 /Vs. On excitation of millimeter-sized crystals, the TRMC signals show, apart from a fast decay, a long-lived tail...
March 8, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Michael A Beuwer, Bas van Hoof, Peter Zijlstra
The high sensitivity of localized surface plasmon resonance sensors to the local refractive index allows for the detection of single-molecule binding events. Though binding events of single objects can be detected by their induced plasmon shift, the broad distribution of observed shifts remains poorly understood. Here, we perform a single-particle study wherein single nanospheres bind to a gold nanorod, and relate the observed plasmon shift to the binding location using correlative microscopy. To achieve this we combine atomic force microscopy to determine the binding location, and single-particle spectroscopy to determine the corresponding plasmon shift...
March 1, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Daniel Rettenwander, Reinhard Wagner, Andreas Reyer, Maximilian Bonta, Lei Cheng, Marca M Doeff, Andreas Limbeck, Martin Wilkening, Georg Amthauer
The interface stability versus Li represents a major challenge in the development of next-generation all-solid-state batteries (ASSB), which take advantage of the inherently safe ceramic electrolytes. Cubic Li7 La3 Zr2 O12 garnets represent the most promising electrolytes for this technology. The high interfacial impedance versus Li is, however, still a bottleneck toward future devices. Herein, we studied the electrochemical performance of Fe3+ -stabilized Li7 La3 Zr2 O12 (LLZO:Fe) versus Li metal and found a very high total conductivity of 1...
February 22, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Shuai Zhang, Qinfu Liu, Feng Gao, Brian J Teppen
Molecular dynamics simulations were performed on kaolinite-formamide complex models with various numbers of formamide molecules loaded in the kaolinite interlayer to explore the basal spacing, energetics, and structure evolution of the kaolinite-formamide complex during the intercalation process. Additionally, the interfacial interactions of formamide with kaolinite interlayer surfaces were calculated. The calculation revealed that the basal spacing of kaolinite was enlarged to 9.6 Å at the beginning of intercalation...
February 15, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Zhenhua Yang, Maria Moffa, Ying Liu, Hongfei Li, Luana Persano, Andrea Camposeo, Rosalba Saija, Maria Antonia Iatì, Onofrio M Maragò, Dario Pisignano, Chang-Yong Nam, Eyal Zussman, Miriam Rafailovich
Hybrid conjugated polymer/fullerene filaments based on MEH-PPV/PVP/PCBM were prepared by electrospinning, and their properties were assessed by scanning electron, atomic and lateral-force, tunneling, and confocal microscopies, as well as by attenuated-total-reflection Fourier transform infrared spectroscopy, photoluminescence quantum yield, and spatially resolved fluorescence. Highlighted features include the ribbon shape of the realized fibers and the persistence of a network serving as a template for heterogeneous active layers in solar cell devices...
February 8, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Alexander E J Hoffman, Louis Vanduyfhuys, Irena Nevjestić, Jelle Wieme, Sven M J Rogge, Hannes Depauw, Pascal Van Der Voort, Henk Vrielinck, Veronique Van Speybroeck
In this work, mid-infrared (mid-IR), far-IR, and Raman spectra are presented for the distinct (meta)stable phases of the flexible metal-organic framework MIL-53(Al). Static density functional theory (DFT) simulations are performed, allowing for the identification of all IR-active modes, which is unprecedented in the low-frequency region. A unique vibrational fingerprint is revealed, resulting from aluminum-oxide backbone stretching modes, which can be used to clearly distinguish the IR spectra of the closed- and large-pore phases...
February 8, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Adam Taylor, René Verhoef, Michael Beuwer, Yuyang Wang, Peter Zijlstra
We demonstrate the all-optical reconstruction of gold nanoparticle geometry using super-resolution microscopy. We employ DNA-PAINT to get exquisite control over the (un)binding kinetics by the number of complementary bases and salt concentration, leading to localization accuracies of ∼5 nm. We employ a dye with an emission spectrum strongly blue-shifted from the plasmon resonance to minimize mislocalization due to plasmon-fluorophore coupling. We correlate the all-optical reconstructions with atomic force microscopy images and find that reconstructed dimensions deviate by no more than ∼10%...
February 1, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Florian Kraushofer, Zdenek Jakub, Magdalena Bichler, Jan Hulva, Peter Drmota, Michael Weinold, Michael Schmid, Martin Setvin, Ulrike Diebold, Peter Blaha, Gareth S Parkinson
The α-Fe2 O3 (11̅02) surface (also known as the hematite r-cut or (012) surface) was studied using low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning tunneling microscopy (STM), noncontact atomic force microscopy (nc-AFM), and ab initio density functional theory (DFT)+ U calculations. Two surface structures are stable under ultrahigh vacuum (UHV) conditions; a stoichiometric (1 × 1) surface can be prepared by annealing at 450 °C in ≈10-6 mbar O2 , and a reduced (2 × 1) reconstruction is formed by UHV annealing at 540 °C...
January 25, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Nelson Y Dzade, Nora H de Leeuw
Layered transition-metal chalcogenides have emerged as a fascinating new class of materials for catalysis. Here, we present periodic density functional theory (DFT) calculations of the adsorption of thiophene and the direct desulfurization reaction pathways on the (001), (011), and (111) surfaces of layered FeS. The fundamental aspects of the thiophene adsorption, including the initial adsorption geometries, adsorption energies, structural parameters, and electronic properties, are presented. From the calculated adsorption energies, we show that the flat adsorption geometries, wherein the thiophene molecule forms multiple π-bonds with the FeS surfaces, are energetically more favorable than the upright adsorption geometries, with the strength of adsorption decreasing in the order FeS(111) > FeS(011) > FeS(001)...
January 11, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Saskia Streubel, Felix Schulze-Zachau, Eric Weißenborn, Björn Braunschweig
Mixed layers of 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate (Sunset Yellow, SSY) and cetyltrimethylammonium bromide (C16 TAB) at the air-water interface were studied using vibrational sum-frequency generation (SFG) and dynamic surface tension measurements. In the bulk, addition of C16 TAB to SSY aqueous solution causes substantial changes in UV/vis absorption spectra, which originate from strong electrostatic interactions between the anionic SSY azo dye with the cationic C16 TAB surfactant. These interactions are a driving force for the formation of SSY/C16 TAB ion pairs...
December 21, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Jan Balajka, Ulrich Aschauer, Stijn F L Mertens, Annabella Selloni, Michael Schmid, Ulrike Diebold
The rutile TiO2 (011) surface exhibits a (2 × 1) reconstruction when prepared by standard techniques in ultrahigh vacuum (UHV). Here we report that a restructuring occurs upon exposing the surface to liquid water at room temperature. The experiment was performed in a dedicated UHV system, equipped for direct and clean transfer of samples between UHV and liquid environment. After exposure to liquid water, an overlayer with a (2 × 1) symmetry was observed containing two dissociated water molecules per unit cell...
November 30, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
María C Gélvez-Rueda, Eline M Hutter, Duyen H Cao, Nicolas Renaud, Constantinos C Stoumpos, Joseph T Hupp, Tom J Savenije, Mercouri G Kanatzidis, Ferdinand C Grozema
The optoelectronic properties of hybrid perovskites can be easily tailored by varying their components. Specifically, mixing the common short organic cation (methylammonium (MA)) with a larger one (e.g., butyl ammonium (BA)) results in 2-dimensional perovskites with varying thicknesses of inorganic layers separated by the large organic cation. In both of these applications, a detailed understanding of the dissociation and recombination of electron-hole pairs is of prime importance. In this work, we give a clear experimental demonstration of the interconversion between bound excitons and free charges as a function of temperature by combining microwave conductivity techniques with photoluminescence measurements...
November 30, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Hongsheng Liu, Cristiana Di Valentin
Magnetite exhibits a famous phase transition, called Verwey transition, at the critical temperature T V of about 120 K. Although numerous efforts have been devoted to the understanding of this interesting transition, up to now, it is still under debate whether a charge ordering and a band gap exist in magnetite above T V . Here, we systematically investigate the charge ordering and the electronic properties of magnetite in its cubic phase using different methods based on density functional theory: DFT+U and hybrid functionals...
November 22, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"