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Chemistry of Materials: a Publication of the American Chemical Society

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https://www.readbyqxmd.com/read/30487664/spectroelectrochemical-signatures-of-surface-trap-passivation-on-cdte-nanocrystals
#1
Ward van der Stam, Indy du Fossé, Gianluca Grimaldi, Julius O V Monchen, Nicholas Kirkwood, Arjan J Houtepen
The photoluminescence (PL) quantum yield of semiconductor nanocrystals (NCs) is hampered by in-gap trap states due to dangling orbitals on the surface of the nanocrystals. While crucial for the rational design of nanocrystals, the understanding of the exact origin of trap states remains limited. Here, we treat CdTe nanocrystal films with different metal chloride salts and we study the effect on their optical properties with in situ spectroelectrochemistry, recording both changes in absorption and photoluminescence...
November 13, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30487663/reactivity-of-amorphous-carbon-surfaces-rationalizing-the-role-of-structural-motifs-in-functionalization-using-machine-learning
#2
Miguel A Caro, Anja Aarva, Volker L Deringer, Gábor Csányi, Tomi Laurila
Systematic atomistic studies of surface reactivity for amorphous materials have not been possible in the past because of the complexity of these materials and the lack of the computer power necessary to draw representative statistics. With the emergence and popularization of machine learning (ML) approaches in materials science, systematic (and accurate) studies of the surface chemistry of disordered materials are now coming within reach. In this paper, we show how the reactivity of amorphous carbon (a-C) surfaces can be systematically quantified and understood by a combination of ML interatomic potentials, ML clustering techniques, and density functional theory calculations...
November 13, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30344371/ab-initio-study-of-sodium-insertion-in-the-%C3%AE-mn-2-o-4-and-dis-ordered-%C3%AE-mn-1-5-ni-0-5-o-4-spinels
#3
Alexandros Vasileiadis, Brian Carlsen, Niek J J de Klerk, Marnix Wagemaker
The main challenge of sodium-ion batteries is cycling stability, which is usually compromised due to strain induced by sodium insertion. Reliable high-voltage cathode materials are needed to compensate the generally lower operating voltages of Na-ion batteries compared to Li-ion ones. Herein, density functional theory (DFT) computations were used to evaluate the thermodynamic, structural, and kinetic properties of the high voltage λ-Mn2 O4 and λ-Mn1.5 Ni0.5 O4 spinel structures as cathode materials for sodium-ion batteries...
October 9, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30270987/one-pot-gram-scale-synthesis-of-hydrogen-terminated-silicon-nanoparticles
#4
Sidharam P Pujari, Hafedh Driss, Fatma Bannani, Barend van Lagen, Han Zuilhof
Silicon nanoparticles (Si NPs) are highly attractive materials for typical quantum dots functions, such as in light-emitting and bioimaging applications, owing to silicon's intrinsic merits of minimal toxicity, low cost, high abundance, and easy and highly stable functionalization. Especially nonoxidized Si NPs with a covalently bound coating serve well in these respects, given the minimization of surface defects upon hydrosilylation of H-terminated Si NPs. However, to date, methods to obtain such H-terminated Si NPs are still not easy...
September 25, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30319176/reversible-photoswitching-function-in-atomic-molecular-layer-deposited-zno-azobenzene-superlattice-thin-films
#5
Aida Khayyami, Maarit Karppinen
We report new types of reversibly photoresponsive ZnO:azobenzene superlattice thin films fabricated through atomic/molecular-layer deposition (ALD/MLD) from diethylzinc, water, and 4,4'-azobenzene dicarboxylic acid precursors. In these ultrathin films, crystalline ZnO layers are interspersed with monomolecular photoactive azobenzene dicarboxylate layers. The thickness of the individual ZnO layers is precisely controlled by the number ( m ) of ALD cycles applied between two subsequent MLD cycles for the azobenzene layers; in our {[(Zn-O) m +(Zn-O2 -C-C6 H4 -N=N-C6 H4 -C-O2 )] n +(Zn-O) m } samples, m ranges from 0 to 240...
September 11, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30270986/colloidal-phase-change-materials-synthesis-of-monodisperse-gete-nanoparticles-and-quantification-of-their-size-dependent-crystallization
#6
Olesya Yarema, Aleksandr Perevedentsev, Vladimir Ovuka, Paul Baade, Sebastian Volk, Vanessa Wood, Maksym Yarema
Phase-change memory materials refer to a class of materials that can exist in amorphous and crystalline phases with distinctly different electrical or optical properties, as well as exhibit outstanding crystallization kinetics and optimal phase transition temperatures. This paper focuses on the potential of colloids as phase-change memory materials. We report a novel synthesis for amorphous GeTe nanoparticles based on an amide-promoted approach that enables accurate size control of GeTe nanoparticles between 4 and 9 nm, narrow size distributions down to 9-10%, and synthesis upscaling to reach multigram chemical yields per batch...
September 11, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30197470/unveiling-the-outstanding-oxygen-mass-transport-properties-of-mn-rich-perovskites-in-grain-boundary-dominated-la-0-8-sr-0-2-mn-1-x-co-x-0-85-o-3%C3%A2-%C3%AE-nanostructures
#7
Aruppukottai M Saranya, Alex Morata, Dolors Pla, Mónica Burriel, Francesco Chiabrera, Iñigo Garbayo, Aitor Hornés, John A Kilner, Albert Tarancón
Ion transport in solid-state devices is of great interest for current and future energy and information technologies. A superior enhancement of several orders of magnitude of the oxygen diffusivity has been recently reported for grain boundaries in lanthanum-strontium manganites. However, the significance and extent of this unique phenomenon are not yet established. Here, we fabricate a thin film continuous composition map of the La0.8 Sr0.2 (Mn1- x Co x )0.85 O3±δ family revealing a substantial enhancement of the grain boundary oxygen mass transport properties for the entire range of compositions...
August 28, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30197469/soft-nondamaging-contacts-formed-from-eutectic-ga-in-for-the-accurate-determination-of-dielectric-constants-of-organic-materials
#8
Evgenia Douvogianni, Xinkai Qiu, Li Qiu, Fatemeh Jahani, Floris B Kooistra, Jan C Hummelen, Ryan C Chiechi
A method for accurately measuring the relative dielectric constant (εr ) of thin films of soft, organic materials is described. The effects of the bombardment of these materials with hot Al atoms, the most commonly used top electrode, are mitigated by using electrodes fabricated from eutectic gallium-indium (EGaIn). The geometry of the electrode is defined by injection into microchannels to form stable structures that are nondamaging and that conform to the topology of the organic thin film. The εr of a series of references and new organic materials, polymers, and fullerene derivatives was derived from impedance spectroscopy measurements for both Al and EGaIn electrodes showing the specific limitations of Al with soft, organic materials and overcoming them with EGaIn to determine their dielectric properties and provide realistic values of εr ...
August 28, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30270985/tuning-exciton-mn-2-energy-transfer-in-mixed-halide-perovskite-nanocrystals
#9
Kunyuan Xu, Andries Meijerink
Doping nanocrystals (NCs) with luminescent activators provides additional color tunability for these highly efficient luminescent materials. In CsPbCl3 perovskite NCs the exciton-to-activator energy transfer (ET) has been observed to be less efficient than in II-VI semiconductor NCs. Here we investigate the evolution of the exciton-to-Mn2+ ET efficiency as a function of composition (Br/Cl ratio) and temperature in CsPbCl3- x Br x :Mn2+ NCs. The results show a strong dependence of the transfer efficiency on Br- content...
August 14, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30245549/mono-and-multilayer-silicene-type-honeycomb-lattices-by-oriented-attachment-of-pbse-nanocrystals-synthesis-structural-characterization-and-analysis-of-the-disorder
#10
Joep L Peters, Thomas Altantzis, Ivan Lobato, Maryam Alimoradi Jazi, Carlo van Overbeek, Sara Bals, Daniel Vanmaekelbergh, Sophia Buhbut Sinai
Nanocrystal (NC) solids are commonly prepared from nonpolar organic NC suspensions. In many cases, the capping on the NC surface is preserved and forms a barrier between the NCs. More recently, superstructures with crystalline connections between the NCs, implying the removal of the capping, have been reported, too. Here, we present large-scale uniform superstructures of attached PbSe NCs with a silicene-type honeycomb geometry, resulting from solvent evaporation under nearly reversible conditions. We also prepared multilayered silicene honeycomb structures by using larger amounts of PbSe NCs...
July 24, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30100672/how-to-get-mechanistic-information-from-partial-pressure-dependent-current-voltage-measurements-of-oxygen-exchange-on-mixed-conducting-electrodes
#11
Alexander Schmid, Ghislain M Rupp, Jürgen Fleig
The oxygen incorporation and evolution reaction on mixed conducting electrodes of solid oxide fuel or electrolysis cells involves gas molecules as well as ionic and electronic point defects in the electrode. The defect concentrations depend on the gas phase and can be modified by the overpotential. These interrelationships make a mechanistic analysis of partial pressure-dependent current-voltage experiments challenging. In this contribution it is described how to exploit this complex situation to unravel the kinetic roles of surface adsorbates and electrode point defects...
July 10, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30022806/electrodeposition-of-hole-transport-layer-on-methylammonium-lead-iodide-film-a-strategy-to-assemble-perovskite-solar-cells
#12
Gergely F Samu, Rebecca A Scheidt, Gary Zaiats, Prashant V Kamat, Csaba Janáky
No abstract text is available yet for this article.
July 10, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30559577/photoinduced-controlled-radical-polymerizations-performed-in-flow-methods-products-and-opportunities
#13
Bonnie L Buss, Garret M Miyake
Photoinduced controlled radical polymerizations (CRPs) have provided a variety of approaches for the synthesis of polymers possessing targeted structures, compositions, and functionalities with the added capability for spatial and temporal control, presenting the potential for new materials development. However, the scalability and reliability of these systems can be limited as a consequence of dependence on uniform irradiation of the reaction to produce well-defined products. In this perspective, we highlight the utility and promise of photo-CRP approaches through an overview of the adaptation of these methodologies to photo-flow reactor systems...
June 26, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/30057438/chemical-activity-of-the-peroxide-oxide-redox-couple-case-study-of-ba-5-ru-2-o-11-in-aqueous-and-organic-solvents
#14
Alexis Grimaud, Antonella Iadecola, Dmitry Batuk, Matthieu Saubanère, Artem M Abakumov, John W Freeland, Jordi Cabana, Haifeng Li, Marie-Liesse Doublet, Gwenaëlle Rousse, Jean-Marie Tarascon
The finding that triggering the redox activity of oxygen ions within the lattice of transition metal oxides can boost the performances of materials used in energy storage and conversion devices such as Li-ion batteries or oxygen evolution electrocatalysts has recently spurred intensive and innovative research in the field of energy. While experimental and theoretical efforts have been critical in understanding the role of oxygen nonbonding states in the redox activity of oxygen ions, a clear picture of the redox chemistry of the oxygen species formed upon this oxidation process is still missing...
June 12, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/29910536/anisotropic-2d-cu-2-x-se-nanocrystals-from-dodecaneselenol-and-their-conversion-to-cdse-and-cuinse-2-nanoparticles
#15
Anne C Berends, Ward van der Stam, Quinten A Akkerman, Johannes D Meeldijk, Joost van der Lit, Celso de Mello Donega
We present the synthesis of colloidal anisotropic Cu2- x Se nanocrystals (NCs) with excellent size and shape control, using the unexplored phosphine-free selenium precursor 1-dodecaneselenol (DDSe). This precursor forms lamellar complexes with Cu(I) that enable tailoring the NC morphology from 0D polyhedral to highly anisotropic 2D shapes. The Cu2- x Se NCs are subsequently used as templates in postsynthetic cation exchange reactions, through which they are successfully converted to CdSe and CuInSe2 quantum dots, nanoplatelets, and ultrathin nanosheets...
June 12, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/29910535/defect-engineering-of-earth-abundant-solar-absorbers-bisi-and-bisei
#16
Alex M Ganose, Saya Matsumoto, John Buckeridge, David O Scanlon
Bismuth-based solar absorbers have recently garnered attention due to their promise as cheap, nontoxic, and efficient photovoltaics. To date, however, most show poor efficiencies far below those seen in commercial technologies. In this work, we investigate two such promising materials, BiSI and BiSeI, using relativistic first-principles methods with the aim of identifying their suitability for photovoltaic applications. Both compounds show excellent optoelectronic properties with ideal band gaps and strong optical absorption, leading to high predicted device performance...
June 12, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/29861547/supramolecular-loop-stitches-of-discrete-block-molecules-on-graphite-tunable-hydrophobicity-by-naphthalenediimide-end-capped-oligodimethylsiloxane
#17
José Augusto Berrocal, Joan Teyssandier, Olga J G M Goor, Steven De Feyter, E W Meijer
The noncovalent functionalization of surfaces has gained widespread interest in the scientific community, and it is progressively becoming an extremely productive research field offering brand new directions for both supramolecular and materials chemistry. As the end-groups often play a dominant role in the surface properties obtained, creating loops with end-groups only at the surface will lead to unexpected architectures and hence properties. Here we report the self-assembly of discrete block molecules-structures in-between block copolymers and liquid crystals-featuring oligodimethylsiloxanes (ODMS) end-capped with naphthalenediimides (NDIs) at the 1-phenyloctane/highly oriented pyrolytic graphite (1-PO/HOPG) interface...
May 22, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/29861546/engineering-of-transition-metal-catalysts-confined-in-zeolites
#18
REVIEW
Nikolay Kosinov, Chong Liu, Emiel J M Hensen, Evgeny A Pidko
Transition metal-zeolite composites are versatile catalytic materials for a wide range of industrial and lab-scale processes. Significant advances in fabrication and characterization of well-defined metal centers confined in zeolite matrixes have greatly expanded the library of available materials and, accordingly, their catalytic utility. In this review, we summarize recent developments in the field from the perspective of materials chemistry, focusing on synthesis, postsynthesis modification, (operando) spectroscopy characterization, and computational modeling of transition metal-zeolite catalysts...
May 22, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/29780208/the-role-of-the-side-chain-on-the-performance-of-n-type-conjugated-polymers-in-aqueous-electrolytes
#19
Alexander Giovannitti, Iuliana P Maria, David Hanifi, Mary J Donahue, Daniel Bryant, Katrina J Barth, Beatrice E Makdah, Achilleas Savva, Davide Moia, Matyáš Zetek, Piers R F Barnes, Obadiah G Reid, Sahika Inal, Garry Rumbles, George G Malliaras, Jenny Nelson, Jonathan Rivnay, Iain McCulloch
We report a design strategy that allows the preparation of solution processable n-type materials from low boiling point solvents for organic electrochemical transistors (OECTs). The polymer backbone is based on NDI-T2 copolymers where a branched alkyl side chain is gradually exchanged for a linear ethylene glycol-based side chain. A series of random copolymers was prepared with glycol side chain percentages of 0, 10, 25, 50, 75, 90, and 100 with respect to the alkyl side chains. These were characterized to study the influence of the polar side chains on interaction with aqueous electrolytes, their electrochemical redox reactions, and performance in OECTs when operated in aqueous electrolytes...
May 8, 2018: Chemistry of Materials: a Publication of the American Chemical Society
https://www.readbyqxmd.com/read/29657360/interplay-between-surface-chemistry-precursor-reactivity-and-temperature-determines-outcome-of-zns-shelling-reactions-on-cuins-2-nanocrystals
#20
Anne C Berends, Ward van der Stam, Jan P Hofmann, Eva Bladt, Johannes D Meeldijk, Sara Bals, Celso de Mello Donega
ZnS shelling of I-III-VI2 nanocrystals (NCs) invariably leads to blue-shifts in both the absorption and photoluminescence spectra. These observations imply that the outcome of ZnS shelling reactions on I-III-VI2 colloidal NCs results from a complex interplay between several processes taking place in solution, at the surface of, and within the seed NC. However, a fundamental understanding of the factors determining the balance between these different processes is still lacking. In this work, we address this need by investigating the impact of precursor reactivity, reaction temperature, and surface chemistry (due to the washing procedure) on the outcome of ZnS shelling reactions on CuInS2 NCs using a seeded growth approach...
April 10, 2018: Chemistry of Materials: a Publication of the American Chemical Society
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