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To understand the electronic-structure change of LiCoO 2 , a widely used cathode material in Li-ion batteries, during charge-discharge, we performed ex situ soft X-ray absorption spectroscopy (XAS) and resonant soft X-ray emission spectroscopy (RXES) of the Co L 3 edge in combination with charge-transfer multiplet calculations. The RXES profile significantly changed for the charged state at 4.2 V vs. Li/Li + , corresponding to the oxidation reaction from a Co 3+ low-spin state for the initial state, while the XAS profile exhibited small changes. For the 4.2-V charged state, we confirmed that approximately half of the initial Co 3+ ions were oxidized to Co 4+ ions. The multiplet calculation of the RXES results revealed that the Co 4+ state has a negative charge-transfer energy and the d 6 L̲ state (L̲ is a ligand hole) is the most stable. Therefore, the O 2p hole created by the strong charge-transfer effect plays a major role in the redox reaction of LiCoO 2 .

Two isostructural cobalt containing polyoxometalate water oxidation catalysts, [Co 4 (H 2 O) 2 (α-PW 9 O 34 ) 2 ] 10- (Co4P2) and [Co 4 (H 2 O) 2 (α-VW 9 O 34 ) 2 ] 10- (Co4V2), exhibit large differences in their catalytic performance. The substitution of phosphorus centers in Co4P2 with redox-active vanadium centers in Co4V2 leads to electronic structure modifications. Evidence for the significance of the vanadium centers to catalysis, predicted by theory, was found from soft X-ray absorption (XAS) and resonant inelastic X-ray scattering (RIXS). The XAS and RIXS spectra determine the electronic structure of the cobalt and vanadium sites in the pre-reaction state of both Co4V2 and Co4P2. High-energy resolution RIXS results reveal that Co4V2 possesses a smaller ligand field within the tetra-cobalt core and a cobalt-to-vanadium charge transfer band. The differences in electronic structures offer insights into the enhanced catalysis of Co4V2.

A structural study is presented of ab initio molecular dynamics simulations of Ge-As-Se chalcogenide glasses performed at the same mean coordination number but differing stoichiometry ranging between Se rich and Se poor glasses. Starting configurations are generated via Reverse Monte Carlo (RMC) simulations of Extended X-ray Absorption Fine Structure (EXAFS) measurements of experimental samples. Structural analysis is presented illustrating the bonding trends found with changing stoichiometry.