Rapid Synthesis of Ruthenium-Copper Nanocomposites as High-Performance Bifunctional Electrocatalysts for Electrochemical Water Splitting.

Development of high-performance, low-cost catalysts for electrochemical water splitting is key to sustainable hydrogen production. Herein, ultrafast synthesis of carbon-supported ruthenium-copper (RuCu/C) nanocomposites is reported by magnetic induction heating, where the rapid Joule's heating of RuCl and CuCl at 200 A for 10 s produces Ru-Cl residues-decorated Ru nanocrystals dispersed on a CuCl scaffold, featuring effective Ru to Cu charge transfer. Among the series, the RuCu/C-3 sample exhibits the best activity in 1 m KOH toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with an overpotential of only -23 and +270 mV to reach 10 mA cm, respectively.

Alkyne-Functionalized Platinum Chalcogenide (S, Se) Nanoparticles.

Metal chalcogenide nanoparticles play a vital role in a wide range of applications and are typically stabilized by organic derivatives containing thiol, amine, or carboxyl moieties, where the nonconjugated particle-ligand interfaces limit the electronic interactions between the inorganic cores and organic ligands. Herein, a wet-chemistry method is developed for the facile preparation of stable platinum chalcogenide (S, Se) nanoparticles capped with acetylene derivatives (e.g.

The impacts of dopants on the small polaron mobility and conductivity in hematite - the role of disorder.

Hematite (α-FeO) is a promising transition metal oxide for various energy conversion and storage applications due to its advantages of low cost, high abundance, and good chemical stability. However, its low carrier mobility and electrical conductivity have hindered the wide application of hematite-based devices. Fundamentally, this is mainly caused by the formation of small polarons, which show conduction through thermally activated hopping.

Stable Cuprous Hydroxide Nanostructures by Organic Ligand Functionalization.

Copper compounds have been extensively investigated for diverse applications. However, studies of cuprous hydroxide (CuOH) have been scarce due to structural metastability. Herein, a facile, wet-chemistry procedure is reported for the preparation of stable CuOH nanostructures via deliberate functionalization with select organic ligands, such as acetylene and mercapto derivatives.

Impacts of ruthenium valence state on the electrocatalytic activity of ruthenium ion-complexed graphitic carbon nitride/reduced graphene oxide nanosheets towards hydrogen evolution reaction.

Design and engineering of effective electrode catalysts represents a critical first step for hydrogen production by electrochemical water splitting. Nanocomposites based on ruthenium atomically dispersed within a carbon scaffold have emerged as viable candidates. In the present study, ruthenium metal centers are atomically embedded within graphitic carbon nitride/reduced graphene oxide nanosheets by thermal refluxing.

Structural Insights on Microwave-Synthesized Antimony-Doped Germanium Nanocrystals.

Doped and alloyed germanium nanocrystals (Ge NCs) are potential candidates for a variety of applications such as photovoltaics and near IR detectors. Recently, bismuth (Bi) as an -type group 15 element was shown to be successfully and kinetically doped into Ge NCs through a microwave-assisted solution-based synthesis, although Bi is thermodynamically insoluble in bulk crystalline Ge. To expand the composition manipulation of Ge NCs, another more common -type group 15 element for semiconductors, antimony (Sb), is investigated.

Platinum Oxide Nanoparticles for Electrochemical Hydrogen Evolution: Influence of Platinum Valence State.

Electrochemical hydrogen generation is a rising prospect for future renewable energy storage and conversion. Platinum remains a leading choice of catalyst, but because of its high cost and low natural abundance, it is critical to optimize its use. In the present study, platinum oxide nanoparticles of approximately 2 nm in diameter are deposited on carbon nitride (C3N4) nanosheets by thermal refluxing of C3N4 and PtCl or PtCl in water.

Extended X-Ray Absorption Fine Structure of ZrWO: Theory vs. Experiment.

Extended x-ray absorption fine structure (EXAFS) is well-suited for investigations of structure and disorder of complex materials. Recently, experimental measurements and analysis of EXAFS have been carried out to elucidate the mechanisms responsible for the negative thermal expansion (NTE) in zirconium tungstate (ZrWO). In contrast to previous work suggesting that transverse O-displacements are largely responsible, the EXAFS analysis suggested that correlated rotations and translations of octahedra and tetrahedra within the structure are a major source.

Room-Temperature Ba(Fe1-x Cox)2 As2 is not Tetragonal: Direct Observation of Magnetoelastic Interactions in Pnictide Superconductors.

Lattice distortions corresponding to Ba displacements with respect to the FeAs sublattice are revealed to break the room-temperature tetragonal symmetry in Ba(Fe1-x Cox)2 As2. The displacements yield twin domains of the size of ≈10 nm. The domain size correlates with the magnitude of the local Fe magnetic moment and its non-monotonic dependence on Co concentration.

Probing the local structure of dilute Cu dopants in fluorescent ZnS nanocrystals using EXAFS.

A local structure study of ZnS nanocrystals, doped with very low concentrations of Cu, was carried out using the EXAFS technique to better understand how Cu substitutes into the host lattice and forms Cu luminescence centers. We show that a large fraction of the Cu have three nearest neighbor S atoms and the Cu-S bond is significantly shortened compared to Zn-S, by ∼0.08 Å.

Background subtraction for fluorescence EXAFS data of a very dilute dopant Z in Z + 1 host.

When conducting EXAFS at the Cu K-edge for ZnS:Cu with very low Cu concentration (<0.04% Cu), a large background was present that increased with energy. This background arises from a Zn X-ray Raman peak, which moves through the Cu fluorescence window, plus the tail of the Zn fluorescence peak.

Degradation and rejuvenation studies of AC electroluminescent ZnS:Cu,Cl phosphors.

We report detailed degradation and rejuvenation studies of AC electroluminescence (EL) of the phosphor ZnS:Cu,Cl, aiming to better understand the physical mechanisms that control EL emission. We find that the AC EL emission spectra vary considerably with the AC driving frequency but all spectra can be fit to a sum of four Gaussians. During degradation, although there is a large overall decrease in amplitude, the shape of the emission spectra measured at a given AC frequency does not change.

Enhanced Cu emission in ZnS : Cu,Cl/ZnS core-shell nanocrystals.

ZnS : Cu,Cl/ZnS core-shell nanocrystals (NCs) have been synthesized via a facile aqueous synthesis method. The shell growth of the NCs was observed via a red-shift in the UV-Vis absorption spectra with increasing NC size. The Cu photoluminescence (PL) emission was enhanced by capping with a thin ZnS shell.

Synthesis, structural, and optical properties of stable ZnS:Cu,Cl nanocrystals.

Stable water-suspendable Cu+-doped ZnS nanocrystals (NCs) have been synthesized with mercaptopropionic acid (MPA) as a capping molecule. The nanocrystals have been characterized using a combination of experimental techniques including UV-vis and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma (ICP), and extended X-ray absorption fine structure (EXAFS). The UV-vis electronic absorption spectrum shows an excitonic peak at 310 nm, characteristic of quantum-confined ZnS NCs.