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A novel well-defined precatalyst for ammonia-selective catalytic reduction of NOx (NH3-SCR), namely, [W(≡CtBu)(CH2tBu)3]/CeO2, was prepared by surface organometallic chemistry and then characterized. Due to the high dispersion of the active phase, this catalyst showed excellent activity after calcination at 500 °C, described by up to 99% conversion of NOx, high N2 selectivity, broad operation temperature window (225–500 °C), and extremely high durability for the selective catalytic reduction of NOx with NH3. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the modulation of optical properties of single-walled carbon nanotubes (SWCNTs) by AuCI3 doping. The van Hove singularity transitions (E11S, E22S, E11M) in absorption spectroscopy disappeared gradually with an increasing doping concentration and a new peak appeared at a high doping concentration. The work function was downshifted up to 0.42 eV by a strong charge transfer from the SWCNTs to AuCl3 by a high level of p-doping. We propose that this large work function shift forces the Fermi level of the SWCNTs to be located deep in the valence band, i.e., highly degenerate, creating empty van Hove singularity states, and hence the work function shift invokes a new asymmetric transition in the absorption spectroscopy from a deeper level to newly generated empty states. [ABSTRACT FROM AUTHOR]

We have evaluated as-grown MoS2 crystals, epitaxially grown on a monocrystalline sapphire by chemical vapor deposition (CVD), with direct electronic band-structure measurements by energy-filtered k-space photoelectron emission microscopy performed with a conventional laboratory vacuum ultraviolet He I light source under off-normal illumination. The valence states of the epitaxial MoS2 were mapped in momentum space down to 7 eV below the Fermi level. Despite the high nucleation density within the imaged area, the CVD MoS2 possesses an electronic structure similar to the free-standing monolayer MoS2 single crystal, and it exhibits hole effective masses of 2.41±0.05m0, and 0.81±0.05m0, respectively, at Γ and K high-symmetry points that are consistent with the van der Waals epitaxial growth mechanism. This demonstrates the excellent ability of the MoS2 CVD on sapphire to yield a highly aligned growth of well-stitched grains through epitaxial registry with a strongly preferred crystallographic orientation. [ABSTRACT FROM AUTHOR]

SiO x electrodes are promising for high-energy-density lithium-ion batteries (LIBs) due to their ability to mitigate volume expansion-induced degradation. Here, we investigate the surface dynamics of SiO x thin-film electrodes cycled in different carbonate-based electrolytes using a combination of ex situ X-ray photoelectron spectroscopy (XPS) and operando synchrotron X-ray reflectivity analyses. The thin-film geometry allows us to probe the depth-dependent chemical composition and electron density from surface to current collector through the solid electrolyte interphase (SEI), the active material, and the thickness evolution during cycling. Results reveal that SiO x lithiation initiates below 0.4 V vs Li + /Li and indicate a close relationship between SEI formation and SiO x electrode lithiation, likely due to the high resistivity of SiO x . We find similar chemical compositions for the SEI in FEC-containing and FEC-free electrolytes but observe a reduced thickness in the former case. In both cases, the SEI thickness decreases during delithiation due to the removal or dissolution of some carbonate species. These findings give insights into the (de)lithiation of SiO x , in particular, during the formation stage, and the effect of the presence of FEC in the electrolyte on the evolution of the SEI during cycling.

Reducing the number of stages, energy costs and carbon footprint of recycling processes is essential to overcome environmental challenges. The interest in replacing the acids used in traditional hydrometallurgical methods with deep eutectic solvents (DES), which are less toxic and more environmentally friendly, has been growing. The aim of this study is to estimate the potential use of this class of solvents in an ionometallurgical process of leaching and electrodeposition to recover silver as part of the recycling of solar panels, a major challenge of the years to come. In the present work, a circular recycling concept based on an iron redox shuttle was studied to leach and recover silver via electrodeposition. Different DESs were evaluated in combination with a hexahydrated iron(iii) chloride oxidizing agent. Ethaline DES has gained significant interest as it can attain a high silver leaching efficiency of 99.9% on crystallized silicon cell scraps at 75 °C. The promising results led to a comprehensive study of limits of this chemical system, focusing on the relation between the concentration of species (iron and water), the interfacial potential of silver (electrochemical measurements), and surface evolution (X-ray photoelectron spectroscopy analysis). Silver leaching was determined as a mixed control mechanism involving chemical and species diffusion dependence. The concentration of iron(iii) chloride appeared crucial, determining the kinetic of formation of a poorly soluble AgCl layer. Electrodeposition from leachate highlighted the need to use an oxygen-free atmosphere to produce high-quality silver. Finally, leaching at 75 °C and electrodeposition at 50 °C of silver from crystallized silicon cell scraps were demonstrated using Ethaline (1 : 2) + FeCl 3 ·6H 2 O (0.12 mol L -1 ) under an argon atmosphere., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

High content nitrogen, sulfur and phosphorus heteroatoms assembled in tree-like dendrimers (DG n ) are confined within the galleries of two-dimensional graphene oxide (GO). The presence of the ternary diethyl- N -ethyl-ammonium groups on the dendrimer peripheries ensures the exfoliation of graphene sheets thereby affording interfacially bridged, three-dimensional heteroatom-enriched graphene-based hybrid nanostructures (DG n -GO). Dendrimer generation (from 1 to 4) that reflects the bulkiness of these conceived nano-trees impacts increasingly the degree of dispersion-exfoliation and sheet desordering. The long-term stability of these aqueous suspensions associated with their handling flexibility allows uniform accommodation of the resulting hybrid materials as flame-retardants in bioplastics., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A carbon-free Li(4)Ti(5)O(12) electrode has shown excellent electrochemical performance without any effort to enhance the electrical conductivity. Partial reduction of Ti(4+) and a metallic Li(7)Ti(5)O(12) phase are suggested to be possible origins of the exceptional behavior., (This journal is © The Royal Society of Chemistry 2012)