Electrolyte decomposition on cathode surfaces of lithium-ion batteries has attracted considerable attention because it leads to battery degradation and formation of a cathode solid–electrolyte interphase. In this study, we used density functional theory (DFT) calculations to investigate the distribution of the adsorption modes of ethylene carbonate (EC) electrolyte molecules and EC decomposition reactions on the (100) surfaces of lithiated (pristine) and delithiated forms of spinel-type LiNi0.5Mn1.5O4 (LNMO) as model cathode surfaces. DFT molecular dynamics (MD) simulations indicated that EC molecules have two characteristic adsorption modes. These two modes can satisfactorily explain the experimental observations and suggest a new feature of electrolyte–cathode interfaces in terms of the control of interfacial dipoles. On the basis of the DFT-MD results, we examined several possible pathways of EC decomposition on the LNMO (100) surfaces and estimated their activation barriers. We then found that the pristine LNMO (100) surface was inert with respect to the EC decomposition, whereas on delithiated surfaces, twofold-coordinated surface oxygen atoms generated by the delithiation process served as active sites for nucleophilic attack on the carbonyl carbon and the methylene group of adsorbed EC molecules. The induction of ring opening of the EC molecule by the former attack, and hydrogen abstraction from the methylene group and subsequent CO2 generation by the latter were consistent with experimental observations.

Intensive effort to tailor photophysics of lead-free perovskites is appealing in recent years. However, their combined electronic and optical property elucidations remain elusive. Here, we report spectroscopic observations of the coexistence Zhang-Rice singlet state and exotic electronic transitions in two-dimensional copper-based perovskites. Herein, several perovskites with different alkylammonium spacers are investigated to unravel their correlated electronic systems and optical responses. Namely, methylammonium, ethylammonium, phenylmethylammonium and phenethylammonium. Using temperature dependent high-resolution X-ray absorption spectroscopy, we observe distinct electronic features highlighting the impact of short spacer chains compared to long-conjugated ligands, demonstrating a pronounced 3d9 and 3d9L signature linewidth variation. Corroborated by density functional theory calculations, the transient dynamics evolution of copper-based hybrid perovskites is influenced by the strong interplay of electron-phonon interactions and geometric constrictions. This finding sheds light on tuning the electronic and optical properties of hybrid perovskites towards efficient photoactive-based devices.

Concave metallic nanocrystals with a high density of low-coordinated atoms on the surface are essential for the realization of unique catalytic properties. Herein, mesoporous palladium nanocrystals (MPNs) that possess various degrees of curvature are successfully synthesized following an approach that relies on a facile polymeric micelle assembly approach. The as-prepared MPNs exhibit larger surface areas compared to conventional Pd nanocrystals and their nonporous counterparts. The MPNs display enhanced electrocatalytic activity for ethanol oxidation when compared to state-of-the-art commercial palladium black and conventional palladium nanocubes used as catalysts. Interestingly, as the degree of curvature increases, the surface-area-normalized activity also increases, demonstrating that the curvature of MPNs and the presence of high-index facets are crucial considerations for the design of electrocatalysts.

A density functional theory (DFT)-based study of ethylene (C2H4) adsorption on a reduced anatase titanium dioxide (TiO2) (001) surface, i.e., with a surface oxygen vacancy (Ovac), is presented.