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Palladium nanoparticles stabilised by aniline modified polymer immobilised ionic liquid is a remarkably active catalyst for the hydrogenation of CO2 to formate; the initial TOF of 500 h−1 is markedly higher than either unmodified catalyst or its benzylamine and N,N-dimethylaniline modified counterparts and is among the highest to be reported for a PdNP-based catalyst. [ABSTRACT FROM AUTHOR]

Zinc tin nitride ( ZnSnN 2) is an emerging ternary nitride semiconductor studied for applications in solar cells, light-emitting diodes, and other optoelectronic devices. For all of these applications, the charge carrier mobility is an important property. However, the dominant electron scattering mechanisms in ZnSnN 2 are unclear, especially in the presence of oxygen that is often incorporated during thin film sputter deposition of this material. In addition, there are no experimental reports on the concentration of defects in such polycrystalline sputtered zinc tin oxynitride Zn 1 + x Sn 1 − x N 2 − 2 x O 2 x (ZTNO) thin films. Here, we address both of these questions using temperature-dependent Hall effect measurements of sputtered ZTNO thin films as a function of Zn composition and O content. The measured temperature dependence of the mobility is fitted to scattering on ionized and neutral defects and to grain boundary scattering. The results indicate that ZTNO is a heavily compensated semiconductor, with a high density of neutral defects dominating the electron scattering processes. First principles theoretical calculations indicate that these neutral defects are likely to originate from the abundant Zn Sn − 2 O N complexes in the ZTNO material. Overall, these results establish the dominant electron scattering mechanisms in polycrystalline sputtered ZTNO and help position this material for future use in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Lepidocrocite-type titanates that reversibly intercalate sodium ions at low potentials (∼0.6 V vs Na/Na+) are promising anode candidates for sodium-ion batteries. However, large amounts of carbon additives are often used to improve their electrical conductivity and overcome poor cycling performance in the electrode composites. To ameliorate electronic transport issues of lepidocrocite titanate (K0.8Ti1.73Li0.27O4, KTL) in sodium-ion batteries, we have designed and synthesized heterostructures of exfoliated lepidocrocite-type titanium oxide (LTO) nanosheets with alternating carbon layers via a solution-based self-assembly approach. Positively charged dopamine (Dopa) was used as the carbon precursor and intercalated between negatively charged exfoliated titania nanosheets through electrostatic interaction. Dopa-intercalated LTO was then annealed under argon to form conductive carbon layers between titania sheets. The carbon content in the heterostructures was controlled by modifying the self-assembly conditions (i.e., pH, stirring duration, and Dopa-to-LTO ratio). Electrodes were prepared using carbonized heterostructures (LTO-C) without adding more carbon to the composites and tested in sodium half-cell configurations. Higher capacities and improved capacity retention over 250 cycles and lower impedance were observed, as the carbon content of LTO-C heterostructures was increased from 0% (LTO nanosheets) to 30%. These results indicate that the self-assembly approach for 2D heterostructured electrode materials is a promising strategy to overcome electronic transport limitations of layered transition-metal oxides and improve their electrochemical performance for next-generation energy storage applications. [ABSTRACT FROM AUTHOR]

Although high energy density and fast charging rates are vital for future advanced battery applications such as electric vehicles (EVs), the impact of fast charge rates is not widely investigated for key technologies such as those based on lithium metal. Here, for the first time, Li metal deposition/dissolution in a superconcentrated ionic liquid (IL) is demonstrated at the high current densities necessary for fast charge technologies. Operation at high current is shown to enhance the cycling efficiency from 64 ± 3% at 1 mA cm−2 up to 96 ± 1% at 20 mA cm−2 on a bare Ni substrate, providing a new path to enable these technologies. XPS, ToF-SIMS and SEM measurements revealed that a stable and LiF-dominated SEI, favourable nucleation and compact dendrite-free Li morphology enabled enhanced cycling efficiency at higher currents. [ABSTRACT FROM AUTHOR]

p-Type transparent conductors and semiconductors still suffer from remarkably low performance compared to their more widespread n-type counterparts, despite extensive investigation into their development. In this contribution, we present a comparative study on the defect chemistry of potential p-type transparent conducting oxides Mg-doped and Ni-doped Cr2O3. Conductivities as high as 28 S cm−1 were achieved by Ni-doping. By benchmarking crystallography and spectroscopy characterization against density functional theory calculations, we show that the incorporation of Ni into Cr2O3 contributes to the composition of the valence band, making the formed holes more delocalized, while Mg states do not interact with the valence band in Mg-doped Cr2O3. Furthermore, it is experimentally proven that Ni has a higher solubility in Cr2O3 than Mg, at least in the highly non-thermodynamic deposition conditions used for these experiments, which directly translates into a higher acceptor concentration. The combination of these two effects means that Ni is a more effective acceptor in Cr2O3 than Mg and explains the improved conductivity observed for the former. [ABSTRACT FROM AUTHOR]

Pt–Co alloys prepared by high energy ball milling synthesis were tested as electrocatalysts for hydrogen fueled Polymer Electrolyte Membrane Fuel Cells (PEMFC). In the present contribution we report on the first results regarding the electrochemical behaviour of two samples of Pt–Co alloys. One sample contains 20 wt.% alloy Pt:Co in the molar ratio 0.25:0.75 and C 80 wt.% and the second one Pt:Co in the molar ratio 0.75:0.25 and C 80 wt.%. The electrochemically active surface (EAS) was determined by cyclic voltammetry data while the electrocatalyst performance in a real cell was obtained by assembling Membrane Electrode Assemblies (MEAs) with the considered sample at the cathode. The results obtained, though indicating a lower performance than all-Pt catalysts, are quite interesting as they point out the importance of the C/Pt, Nafion/Pt and Pt/Co ratios that exert a deep influence onto the cell performance. [ABSTRACT FROM AUTHOR]