Atomic-Layer-Deposited Aluminum Oxide Thin Films Probed with X-ray Scattering and Compared to Molecular Dynamics and Density Functional Theory Models.

A better understanding of amorphous aluminum oxide's structure and electronic properties is obtained through combined experimental and computational approaches. Grazing incidence X-ray scattering measurements were carried out on aluminum oxide thin films grown using thermal atomic layer deposition. The corresponding pair distribution functions (PDFs) showed structures similar to previously reported PDFs of solid-state amorphous alumina and molten alumina.

Shedding X-ray Light on the Interfacial Electrochemistry of Silicon Anodes for Li-Ion Batteries.

Electrochemical alloying reactions of group IV elements, such as Si, Ge, or Sn, with lithium provide a promising route to next-generation anode materials for lithium-ion batteries (LIBs) due to their high volumetric and gravimetric capacities. However, commercialization of these anodes is still sparse owing to quick capacity fading and limited Coulombic efficiency, which arise from large volume expansion leading to particle cracking and subsequent electrochemical inactivity. As a result, the solid electrolyte interphase (SEI), originating in the decomposition of the electrolyte upon battery operation outside the electrolyte's thermodynamic stability window, grows uncontrollably.

In Situ Study of Silicon Electrode Lithiation with X-ray Reflectivity.

Surface sensitive X-ray reflectivity (XRR) measurements were performed to investigate the electrochemical lithiation of a native oxide terminated single crystalline silicon (100) electrode in real time during the first galvanostatic discharge cycle. This allows us to gain nanoscale, mechanistic insight into the lithiation of Si and the formation of the solid electrolyte interphase (SEI). We describe an electrochemistry cell specifically designed for in situ XRR studies and have determined the evolution of the electron density profile of the lithiated Si layer (LiSi) and the SEI layer with subnanometer resolution.

Measurement and Modeling of Short and Medium Range Order in Amorphous Ta2O5 Thin Films.

Amorphous films and coatings are rapidly growing in importance. Yet, there is a dearth of high-quality structural data on sub-micron films. Not understanding how these materials assemble at atomic scale limits fundamental insights needed to improve their performance.

Structure of the floating water bridge and water in an electric field.

The floating water bridge phenomenon is a freestanding rope-shaped connection of pure liquid water, formed under the influence of a high potential difference (approximately 15 kV). Several recent spectroscopic, optical, and neutron scattering studies have suggested that the origin of the bridge is associated with the formation of anisotropic chains of water molecules in the liquid. In this work, high energy X-ray diffraction experiments have been performed on a series of floating water bridges as a function of applied voltage, bridge length, and position within the bridge.

Dramatically enhanced cleavage of the C-C bond using an electrocatalytically coupled reaction.

This paper describes a generalized approach for the selective electrocatalytic C-C bond splitting in aliphatic alcohols at low temperature in aqueous state, with ethanol as an example. We show that selective C-C bond cleavage, leading to carbon dioxide, is possible in high pH aqueous media at low overpotentials. This improved selectivity and activity is achieved using a solution-born co-catalyst based on Pb(IV) acetate, which controls the mode of the ethanol adsorption so as to facilitate direct activation of the C-C bond.

Structural and mechanistic revelations on an iron conversion reaction from pair distribution function analysis.

Not simply small particles: pair distribution function analysis yields comprehensive insights into the electrochemical reaction of α-Fe(2)O(3) with lithium. The metallic Fe formed in this reaction was found to be defect-rich nanoparticles that restructure continuously without growing-an unusual characteristic likely linked to its highly reversible capacity.

Efficient simultaneous reverse Monte Carlo modeling of pair-distribution functions and extended x-ray-absorption fine structure spectra of crystalline disordered materials.

An efficient implementation of simultaneous reverse Monte Carlo (RMC) modeling of pair distribution function (PDF) and EXAFS spectra is reported. This implementation is an extension of the technique established by Krayzman et al. [J.