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Journal of Physical Chemistry. C, Nanomaterials and Interfaces

Ana Beatriz Ferreira Vitoreti, Said Agouram, Mauricio Solis de la Fuente, Vicente Muñoz-Sanjosé, Marco Antônio Schiavon, Iván Mora-Seró
Halide perovskites are revolutionizing the photovoltaic and optoelectronic fields with outstanding performances obtained in a remarkably short time. However, two major challenges remain: the long-term stability and the Pb content, due to its toxicity. Despite the great effort carried out to substitute the Pb by a less hazardous element, lead-free perovskite still remains more unstable than lead-containing perovskites and presents lower performance as well. In this work, we demonstrate the colloidal preparation of Cs-Pb-Sn-Br nanoparticles (NPs) where Sn is incorporated up to 18...
June 28, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Attila Kormányos, Dorottya Hursán, Csaba Janáky
In this study, we investigated the photoelectrochemical behavior of poly(3,4-ethylenedioxythiophene) (PEDOT)/carbon nanotube (CNT) and PEDOT/graphene nanocomposite photoelectrodes for the first time. Electrodeposition allowed control of both the composition and the morphology (as demonstrated by both transmission and scanning electron microscopy images) and also ensured an intimate contact between the PEDOT film and the nanocarbon scaffold. The effect of CNT and graphene on the photoelectrochemical behavior of the nanocomposite samples was studied by linear sweep photovoltammetry, incident photon-to-charge-carrier conversion efficiency measurements, and long-term photoelectrolysis coupled with gas-chromatographic product analysis...
June 28, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Naomi Winckelmans, Thomas Altantzis, Marek Grzelczak, Ana Sánchez-Iglesias, Luis M Liz-Marzán, Sara Bals
Three dimensional (3D) characterization of structural defects in nanoparticles by transmission electron microscopy is far from straightforward. We propose the use of a dose-efficient approach, so-called multimode tomography, during which tilt series of low and high angle annular dark field scanning transmission electron microscopy projection images are acquired simultaneously. In this manner, not only reliable information can be obtained concerning the shape of the nanoparticles, but also the twin planes can be clearly visualized in 3D...
June 28, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Andrea Navarro-Quezada, Ebrahim Ghanbari, Thorsten Wagner, Peter Zeppenfeld
Perfluoropentacene (PFP) is an organic material that has been widely studied over the last years and has already found applications in organic electronics. However, fundamental physical questions, such as the structural formation and the preferential orientation of the molecules during deposition on metal surfaces, are still not fully understood. In this work, we report on a unique in-plane molecular reorientation during the completion of the first monolayer of PFP on the Ag(110) surface. To characterize the molecular alignment, we have monitored the deposition process in real time using polarization-dependent differential reflectance spectroscopy and reflectance anisotropy spectroscopy...
June 21, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Carlo van Overbeek, Joep L Peters, Susan A P van Rossum, Marc Smits, Marijn A van Huis, Daniel Vanmaekelbergh
The realization of materials with new optoelectronic properties draws much scientific attention toward the field of nanocrystal superstructures. Low-dimensional superstructures created by interfacial assembly and oriented attachment of PbSe nanocrystals are a striking example because theory showed that PbSe sheets with a honeycomb geometry possess non-trivial flat bands and Dirac cones in the valence and conduction bands. Here, we report on the formation of one-dimensional linear and zigzag structures and two-dimensional (2D) square and honeycomb structures for the entire lead chalcogenide family: PbX (X = S, Se, Te)...
June 14, 2018: 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
Roman V Shchepin, Lamya Jaigirdar, Eduard Y Chekmenev
Simultaneous reversible chemical exchange of parahydrogen and to-be-hyperpolarized substrate on metal centers enables spontaneous transfer of spin order from parahydrogen singlet to nuclear spins of the substrate. When performed at sub-micro-Tesla magnetic field, this technique of NMR Signal Amplification by Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH). SABRE-SHEATH has been shown to hyperpolarize nitrogen-15 sites of a wide range of biologically interesting molecules to a high polarization level ( P > 20%) in one minute...
March 8, 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
Jacobine J H A van Hest, Gerhard A Blab, Hans C Gerritsen, Celso de Mello Donega, Andries Meijerink
The localized inner 4f shell transitions of lanthanide ions are largely independent of the local surroundings. The luminescence properties of Ln3+ ions doped into nanocrystals (NCs) are therefore similar to those in bulk crystals. Quantum size effects, responsible for the unique size-dependent luminescence of semiconductor NCs, are generally assumed not to influence the optical properties of Ln3+ -doped insulator NCs. However, phonon confinement effects have been reported to hamper relaxation between closely spaced Stark levels in Ln3+ -doped NCs...
February 22, 2018: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
C J Powell, W S M Werner, H Kalbe, A G Shard, D G Castner
We assessed two approaches for determining shell thicknesses of core-shell nanoparticles (NPs) by X-ray photoelectron spectroscopy (XPS). These assessments were based on simulations of photoelectron peak intensities for Au-core/C-shell, C-core/Au-shell, Cu-core/Al-shell, and Al-core/Cu-shell NPs with a wide range of core diameters and shell thicknesses. First, we demonstrated the validity of an empirical equation developed by Shard for determinations of shell thicknesses. Values of shell thicknesses from the Shard equation typically agreed with actual shell thicknesses to better than 10 %...
February 22, 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
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