Spectrally Narrow Blue-Light Emission from Nonstoichiometric AgGaS Quantum Dots for Application to Light-Emitting Diodes.

Luminescence color tuning of less toxic I-III-VI-based quantum dots (QDs) has been intensively investigated for application in wide-color-gamut displays. However, the emission peaks of these multinary QDs are relatively broad in the blue-light region compared to those in the green and red regions. Here, we report the synthesis of AgGaS (AGS) QDs that show a narrow blue emission peak through nonstoichiometry control and surface defect engineering.

One-pot synthesis of Ag-In-Ga-S nanocrystals embedded in a GaO matrix and enhancement of band-edge emission by Na doping.

I-III-VI-based semiconductor quantum dots (QDs) have been intensively explored because of their unique controllable optoelectronic properties. Here we report one-pot synthesis of Na-doped Ag-In-Ga-S (AIGS) QDs incorporated in a GaO matrix. The obtained QDs showed a sharp band-edge photoluminescence peak at 557 nm without a broad-defect site emission.

Spectrally narrow band-edge photoluminescence from AgInS-based core/shell quantum dots for electroluminescence applications.

This study presents a facile synthesis of cadmium-free ternary and quaternary quantum dots (QDs) and their application to light-emitting diode (LED) devices. AgInS ternary QDs, developed as a substitute for cadmium chalcogenide QDs, exhibited spectrally broad photoluminescence due to intrinsic defect levels. Our group has successfully achieved narrow band-edge PL by a coating with gallium sulfide shell.

Development of Cu-In-Ga-S quantum dots with a narrow emission peak for red electroluminescence.

Narrowing the emission peak width and adjusting the peak position play a key role in the chromaticity and color accuracy of display devices with the use of quantum dot light-emitting diodes (QD-LEDs). In this study, we developed multinary Cu-In-Ga-S (CIGS) QDs showing a narrow photoluminescence (PL) peak by controlling the Cu fraction, i.e.

Quantum-Dot Light-Emitting Diodes Exhibiting Narrow-Spectrum Green Electroluminescence by Using Ag-In-Ga-S/GaS Quantum Dots.

Quantum dots (QDs), which have high color purity, are expected to be applied as emitting materials to wide-color-gamut displays. To enable their use as an alternative to Cd-based QDs, it is necessary to improve the properties of QDs composed of low-toxicity materials. Although multielement QDs such as Ag-In-Ga-S are prone to spectrally broad emission from defect sites, a core/shell structure covered with a GaS shell is expected to enable sharp emission from band-edge transitions.

Electrocatalyst Fabrication Using Metal Nanoparticles Prepared in Ionic Liquids.

Metal nanoparticle-based electrocatalysts are widely used in electronic devices, which serve for electrochemical reactions like oxygen reduction reaction, alcohol oxidation and CO reduction reaction. These catalyst-dependent reactions are the key of the emerging clean energy systems. Catalyst design and synthesis therefore have received keen attention in past decades.

Composition control of alloy nanoparticles consisting of bulk-immiscible Au and Rh metals an ionic liquid/metal sputtering technique for improving their electrocatalytic activity.

AuRh bimetallic alloy nanoparticles (NPs) were successfully prepared by simultaneous sputtering of Au and Rh in a room-temperature ionic liquid (RTIL) of ,-diethyl--methyl--(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF). Bimetallic AuRh alloy NPs of 1-2 nm in size were formed in the RTIL. The alloy composition was controllable by changing the surface areas of Au and Rh plates used as sputtering targets.

Surface ligand chemistry on quaternary Ag(In Ga )S semiconductor quantum dots for improving photoluminescence properties.

Ternary and quaternary semiconductor quantum dots (QDs) are candidates for cadmium-free alternatives. Among these, semiconductors containing elements from groups 11, 13, and 16 (, I-III-VI) are attracting increasing attention since they are direct semiconductors whose bandgap energies in the bulk state are tunable between visible and near infrared. The quaternary system of alloys consisting of silver indium sulfide (AgInS; bandgap energy: = 1.

Synthesis of multicolor-emitting nitrogen-sulfur co-doped carbon dots and their photochemical studies for sensing applications.

Photoluminescent carbon dots (CDs) possess several advantages, which include high stability and a non-toxicity that are essential in different applications such as catalysis, drug delivery, and sensors. The presence of heteroatoms modifies their physicochemical characteristics. In this work, a combination of CDs is manufactured utilizing a solvothermal technique using citric acid and thiourea.

Impact of sp carbon material species on Pt nanoparticle-based electrocatalysts produced by one-pot pyrolysis methods with ionic liquids.

Pt-nanoparticle-supported graphene nanoplatelets (Pt/GNPs) and multiwalled carbon nanotube composite (Pt/MWCNTs) electrocatalysts for the oxygen reduction reaction (ORR) can be prepared using a one-pot method through the pyrolytic decomposition of the platinum precursor, platinum(ii) bis(acetylacetonate) (Pt(acac)) in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([Cmim][TfN]) or ,,-trimethyl--propylammonium bis(trifluoromethanesulfonyl)amide ([N][TfN]) ionic liquids (ILs) with the target sp carbon support. In this one-pot pyrolysis method, which does not require any reagents to reduce Pt metal precursors or stabilize Pt nanoparticles, Pt nanoparticles are readily immobilized onto the sp surface by a thin IL layer formed at the interface, which can work as a binder. We used three types of sp carbon materials with different geometric shapes (graphene nanoplatelets with <3 (GNPs-3) and 18-24 layers (GNPs-20) and multiwalled carbon nanotubes (MWCNTs)) to investigate Pt nanoparticle formation and anchoring.

On-Surface Metathesis of an Ionic Liquid on Ag(111).

We investigated the adsorption, surface enrichment, ion exchange, and on-surface metathesis of ultrathin mixed IL films on Ag(111). We stepwise deposited 0.5 ML of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) and 1.

Aluminum metal anode rechargeable batteries with sulfur-carbon composite cathodes and inorganic chloroaluminate ionic liquid.

Promising sulfurized polyethylene glycol (SPEG) composite cathodes with a high-rate capability over 3000 mA g at 393 K are fabricated for Al metal anode rechargeable batteries with a 61.0-26.0-13.

Adsorption, Wetting, Growth, and Thermal Stability of the Protic Ionic Liquid Diethylmethylammonium Trifluoromethanesulfonate on Ag(111) and Au(111).

We have studied the adsorption, wetting, growth, and thermal evolution of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) on Au(111) and Ag(111). Ultrathin films were deposited at room temperature (RT) and at 90 K, and were characterized by angle-resolved X-ray photoelectron spectroscopy. For both surfaces, we observe that independent of temperature, initially, a closed 2D wetting layer forms.

Luminescent Quaternary Ag(InGa)S/GaS Core/Shell Quantum Dots Prepared Using Dithiocarbamate Compounds and Photoluminescence Recovery via Post Treatment.

Cadmium-free quantum dots (QDs) consisting of silver-indium-gallium-sulfide (AIGS) quaternary semiconductors were successfully synthesized using a metal-dithiocarbamate complex with sufficiently high reactivity to produce metal sulfides. The introduction of a gallium diethyldithiocarbamate precursor decreased the reaction temperature to produce active intermediates, which were subsequently converted into AIGS QDs at 150 °C with silver and indium acetates. Because of the low reaction temperature, AIGS QDs with a tetragonal crystal phase were produced selectively, which favorably generated band-edge emission whose full width at half-maximum is smaller than 40 nm after they were coated with gallium sulfide (GaS) shells.

Synthesis and Pyrolysis of Fullerenol-stabilized Pt Nanocolloids as a unique Approach to Pt-doped Carbon.

An aqueous colloidal dispersion of Pt nanoparticles (NPs) stabilized by fullerenol C (OH) (Pt:C (OH) ) was successfully synthesized via liquid-phase chemical reduction. The subsequent pyrolysis of Pt:C (OH) at different temperatures was conducted to afford Pt-doped carbon with different chemical compositions (Pt:C60 ). X-ray absorption spectroscopy (XAS) and Infrared (IR) absorption spectroscopy and thermogravimetric measurements revealed that the thus-prepared nanocomposite consists of Pt NPs and high valent Pt-C (OH) complex.

Inorganic AlCl-alkali metal thiocyanate ionic liquids as electrolytes for electrochemical Al technologies.

A series of inorganic AlCl-alkali metal thiocyanate (ASCN: A = Li, Na, K) ionic liquids (ILs) are demonstrated as electrolytes for Al electrodeposition and Al-anion rechargeable batteries (AARBs) at 303-363 K. Al deposits with a unique flake nanostructure are obtained in these electrolytes. The assembled AARBs show a stable cyclability over 250 cycles with a reversible capacity of ca.

One-Pot Synthesis of PtNi Alloy Nanoparticle-Supported Multiwalled Carbon Nanotubes in an Ionic Liquid Using a Staircase Heating Process.

High-performance PtNi alloy nanoparticle-supported multiwalled carbon nanotube composite (PtNi/MWCNT) electrocatalysts can be prepared via one-pot preparation for oxygen reduction reaction. This route of preparation utilizes the pyrolytic decomposition of metal precursors, such as Pt(acac) with Ni precursors, nickel bis(trifluoromethanesulfonyl)amide (Ni[TfN]) or nickel acetylacetonate (Ni(acac)), in an ionic liquid (IL), ,,-trimethyl--propylammonium bis(trifluoromethanesulfonyl)amide ([N][TfN]). Currently, there is insufficient information concerning the effect of difference in preparation conditions on the formation mechanism and catalytic activity of PtNi/MWCNT.

Controlling the oxidation state of molybdenum oxide nanoparticles prepared by ionic liquid/metal sputtering to enhance plasmon-induced charge separation.

Nanoparticles composed of molybdenum oxide, MoO , were successfully prepared by room-temperature ionic liquid (RTIL)/metal sputtering followed by heat treatment. Hydroxyl groups in RTIL molecules retarded the coalescence between MoO NPs during heat treatment at 473 K in air, while the oxidation state of Mo species in MoO nanoparticles (NPs) could be modified by changing the heat treatment time. An LSPR peak was observed at 840 nm in the near-IR region for MoO NPs of 55 nm or larger in size that were annealed in a hydroxyl-functionalized RTIL.

Hot electron transfer in Zn-Ag-In-Te nanocrystal-methyl viologen complexes enhanced with higher-energy photon excitation.

The dynamics of hot electron transfer from Zn-Ag-In-Te (ZAITe) nanocrystals (NCs) to adsorbed methyl viologen (MV) were investigated by transient absorption spectroscopy. The bleaching of the exciton peak in the ZAITe NC-MV complexes evolved faster than that of ZAITe NCs. The hot electron transfer efficiency increased from 45% to 72% with increasing excitation photon energy.

Electron microscopy using ionic liquids for life and materials sciences.

An ionic liquid (IL) is a salt consisting of only cations and anions, which exists in the liquid state at room temperature. Interestingly ILs combine various favorable physicochemical properties, such as negligible vapor pressure, flame resistance, relatively high ionic conductivity, wide electrochemical window, etc. To take advantage of two specific features of ILs, viz.

Analytical Measurements to Elucidate Structural Behavior of 2,5-Dimethoxy-1,4-benzoquinone During Charge and Discharge.

Organic compounds as electrode materials can contribute to sustainability because they are nontoxic and environmentally abundant. The working mechanism during charge-discharge for reported organic compounds as electrode materials is yet to be completely understood. In this study, the structural behavior of 2,5-dimethoxy-1,4-benzoquinone (DMBQ) during charge-discharge is investigated by using NMR spectroscopy, energy-dispersive X-ray spectroscopy, magnetic measurements, operando Raman spectroscopy, and operando X-ray diffraction.

Core Nanoparticle Engineering for Narrower and More Intense Band-Edge Emission from AgInS/GaS Core/Shell Quantum Dots.

Highly luminescent silver indium sulfide (AgInS) nanoparticles were synthesized by dropwise injection of a sulfur precursor solution into a cationic metal precursor solution. The two-step reaction including the formation of silver sulfide (AgS) nanoparticles as an intermediate and their conversion to AgInS nanoparticles, occurred during the dropwise injection. The crystal structure of the AgInS nanoparticles differed according to the temperature of the metal precursor solution.

Epoxy-Containing Ionic Liquids with Tunable Functionality.

New types of ionic liquids (ILs) with an epoxy group on a piperidinium-type cation were successfully synthesized by the simple anion exchange reaction of a solid 1-allyl-1-(oxiran-2-ylmethyl)piperidinium bromide, which was designed in this study. Unfortunately, the physicochemical properties, e.g.

Use of ionic liquid for X-ray micro-CT specimen preparation of imbibed seeds.

X-ray micro-CT is one of the most useful techniques to examine 3D cellular architecture inside dry seeds. However, the examination of imbibed seeds is difficult because immersion in water causes a decline in the image quality. Here, we examined the use of ionic liquids for specimen preparation of chemically fixed imbibed seeds of Arabidopsis.

Wavelength-Tunable Band-Edge Photoluminescence of Nonstoichiometric Ag-In-S Nanoparticles via Ga Doping.

The nonstoichiometry of I-III-VI semiconductor nanoparticles, especially the ratio of group I to group III elements, has been utilized to control their physicochemical properties. We report the solution-phase synthesis of nonstoichiometric Ag-In-S and Ag-In-Ga-S nanoparticles and results of the investigation of their photoluminescence (PL) properties in relation to their chemical compositions. While stoichiometric AgInS nanoparticles simply exhibited only a broad PL band originating from defect sites in the particles, a narrow band edge PL peak newly appeared with a decrease in the Ag fraction in the nonstoichiometric Ag-In-S nanoparticles.