In this manuscript, we report a detailed physico-chemical comparison between the α- and β-polymorphs of the NaMnO₂ compound, a promising material for application in positive electrodes for secondary aprotic sodium batteries. In particular, the structure and vibrational properties, as well as electrochemical performance in sodium batteries, are compared to highlight differences and similarities. We exploit both laboratory techniques (Raman spectroscopy, electrochemical methods) and synchrotron radiation experiments (Fast-Fourier Transform Infrared spectroscopy, and X-ray diffraction). Notably the vibrational spectra of these phases are here reported for the first time in the literature as well as the detailed structural analysis from diffraction data. DFT+U calculations predict both phases to have similar electronic features, with structural parameters consistent with the experimental counterparts. The experimental evidence of antisite defects in the beta-phase between sodium and manganese ions is noticeable. Both polymorphs have been also tested in aprotic batteries by comparing the impact of different liquid electrolytes on the ability to de-intercalated/intercalate sodium ions. Overall, the monoclinic α-NaMnO₂ shows larger reversible capacity exceeding 175 mAhg⁻¹ at 10 mAg⁻¹.

Two-dimensional topological insulators with propagating topological edge states are promising for dissipationless transport, while their one-dimensional analogs are capable of hosting localized topological junction states that are mainly envisaged for quantum computing and spintronics. Here, in contrast, we propose to use the localized nature of topological junction states for sensing applications. We report a systematic topological classification of a wide class of graphene nanoribbons represented by already synthesized extended chevron species. Using this classification, we theoretically model a double junction transport that shows an enhanced interaction with the NO₂ molecule. Our results show that topological junction states of nanoribbons can open an avenue for topological sensing and junction-assisted chemistry applications.

We report on DFT-TDDFT studies of the structural, electronic and vibrational properties of ${\mathrm{B}}_{24}{\mathrm{N}}_{24}$ nanocapsules and the effect of encapsulation of homonuclear diatomic halogens ($\mathrm{C}{\mathrm{l}}_2$, $\mathrm{B}{\mathrm{r}}_2$ and ${\mathrm{I}}_2$) and chalcogens (${\mathrm{S}}_2$ and $\mathrm{S}{\mathrm{e}}_2$) on the interaction of the ${\mathrm{B}}_{24}{\mathrm{N}}_{24}$ nanocapsules with the divalent magnesium cation. In particular, to foretell whether these BN nanostructures could be proper negative electrodes for magnesium-ion batteries, the structural, vibrational and electronic properties, as well as the interaction energy and the cell voltage, which is important for applications, have been computed for each system, highlighting their differences and similarities. The encapsulation of halogen and chalcogen diatomic molecules increases the cell voltage, with an effect enhanced down groups 16 and 17 of the periodic table, leading to better performing anodes and fulfilling a remarkable cell voltage of 3.61 V for the iodine-encapsulated system.

N‐Heterocyclic carbenes (NHCs) are established ligands for various surfaces, known for their strong binding, ability to form self‐assembled monolayers, and modular structure. However, semiconductor surface modification with NHCs is still in its infancy despite its technological importance. Although previous studies focused on silicon, III‐V compound semiconductors offer direct bandgaps and high electron mobilities, making them ideal for (opto‐)electronics. This study examines the adsorption of different NHCs on GaAs, a prototypical III‐V material, using scanning tunneling microscopy, density functional theory, X‐ray photoelectron spectroscopy, low‐energy electron diffraction, and reflectance anisotropy spectroscopy. Covalent binding to the surface and the formation of well‐ordered NHC monolayers are observed, along with exceptionally large work function reductions. The unique structural features of NHCs enable precise control over film structure, ordering, and electronic properties.