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The molecular structure of the electrical double layer determines the chemistry in all electrochemical processes. Using x-ray absorption spectroscopy (XAS), we probed the structure of water near gold electrodes and its bias dependence. Electron yield XAS detected at the gold electrode revealed that the interfacial water molecules have a different structure from those in the bulk. First principles calculations revealed that ∼50% of the molecules lie flat on the surface with saturated hydrogen bonds and another substantial fraction with broken hydrogen bonds that do not contribute to the XAS spectrum because their core-excited states are delocalized by coupling with the gold substrate. At negative bias, the population of flat-lying molecules with broken hydrogen bonds increases, producing a spectrum similar to that of bulk water.

The process of carbon capture and sequestration has been proposed as a method of mitigating the build-up of greenhouse gases in the atmosphere. If implemented, the cost of electricity generated by a fossil fuel-burning power plant would rise substantially, owing to the expense of removing CO 2 from the effluent stream. There is therefore an urgent need for more efficient gas separation technologies, such as those potentially offered by advanced solid adsorbents. Here we show that diamine-appended metal-organic frameworks can behave as ‘phase-change’ adsorbents, with unusual step-shaped CO 2 adsorption isotherms that shift markedly with temperature. Results from spectroscopic, diffraction and computational studies show that the origin of the sharp adsorption step is an unprecedented cooperative process in which, above a metal-dependent threshold pressure, CO 2 molecules insert into metal-amine bonds, inducing a reorganization of the amines into well-ordered chains of ammonium carbamate. As a consequence, large CO 2 separation capacities can be achieved with small temperature swings, and regeneration energies appreciably lower than achievable with state-of-the-art aqueous amine solutions become feasible. The results provide a mechanistic framework for designing highly efficient adsorbents for removing CO 2 from various gas mixtures, and yield insights into the conservation of Mg 2+ within the ribulose-1,5-bisphosphate carboxylase/oxygenase family of enzymes. A cooperative insertion mechanism for CO 2 adsorption is shown to generate highly efficient adsorbents for carbon capture applications. Efficient CO 2 absorption in a metal-organic framework Advanced solid adsorbents are being investigated as potential agents for efficient gas separation technologies that could help make carbon capture technologies more economical. This paper probes the mechanism of carbon dioxide adsorption of a previously reported diamine-appended metal-organic framework. This material demonstrates unusual and potentially practically useful adsorption properties. The authors find that CO 2 adsorbs through insertion into the highly stable metal-amine bonds of the metal-organic framework. As a consequence of the homogenous and perfect spacing of amines, as dictated by the framework's topology, the insertion of a single CO 2 molecule induces neighbouring sites to also adsorb CO 2 in an unprecedented chain reaction process.

Although multiple oxide-based solid electrolyte materials with intrinsically high ionic conductivities have emerged, practical processing and synthesis routes introduce grain boundaries and other interfaces that can perturb primary conduction channels. To directly probe these effects, we demonstrate an efficient and general mesoscopic computational method capable of predicting effective ionic conductivity through a complex polycrystalline oxide-based solid electrolyte microstructure without relying on simplified equivalent circuit description. We parameterize the framework for Li7-xLa3Zr2O12 (LLZO) garnet solid electrolyte by combining synthetic microstructures from phase-field simulations with diffusivities from molecular dynamics simulations of ordered and disordered systems. Systematically designed simulations reveal an interdependence between atomistic and mesoscopic microstructural impacts on the effective ionic conductivity of polycrystalline LLZO, quantified by newly defined metrics that characterize the complex ionic transport mechanism. Our results provide fundamental understanding of the physical origins of the reported variability in ionic conductivities based on an extensive analysis of literature data, while simultaneously outlining practical design guidance for achieving desired ionic transport properties based on conditions for which sensitivity to microstructural features is highest. Additional implications of our results are discussed, including a possible connection between ion conduction behavior and dendrite formation.

Over one million tons of CS 2 are produced annually, and emissions of this volatile and toxic liquid, known to generate acid rain, remain poorly controlled. As such, materials capable of reversibly capturing this commodity chemical in an energy-efficient manner are of interest. Recently, we detailed diamine-appended metal–organic frameworks capable of selectively capturing CO 2 through a cooperative insertion mechanism that promotes efficient adsorption–desorption cycling. We therefore sought to explore the ability of these materials to capture CS 2 through a similar mechanism. Employing crystallography, spectroscopy, and gas adsorption analysis, we demonstrate that CS 2 is indeed cooperatively adsorbed in N,N -dimethylethylenediamine-appended M 2 (dobpdc) (M = Mg, Mn, Zn; dobpdc 4-  = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate), via the formation of electrostatically paired ammonium dithiocarbamate chains. In the weakly thiophilic Mg congener, chemisorption is cleanly reversible with mild thermal input. This work demonstrates that the cooperative insertion mechanism can be generalized to other high-impact target molecules. The large-scale production of CS 2 presents both environmental and biological hazards, yet adsorbents capable of CS 2 capture remain scarcely explored. Here, Long and colleagues demonstrate that CS 2 is adsorbed in diamine-appended metal–organic frameworks through a cooperative and chemically specific insertion process.

Layered boron compounds have attracted significant interest in applications from energy storage to electronic materials to device applications, owing in part to a diversity of surface properties tied to specific arrangements of boron atoms. Here we report the energy landscape for surface atomic configurations of MgB 2 by combining first-principles calculations, global optimization, material synthesis and characterization. We demonstrate that contrary to previous assumptions, multiple disordered reconstructions are thermodynamically preferred and kinetically accessible within exposed B surfaces in MgB 2 and other layered metal diborides at low boron chemical potentials. Such a dynamic environment and intrinsic disordering of the B surface atoms present new opportunities to realize a diverse set of 2D boron structures. We validated the predicted surface disorder by characterizing exfoliated boron-terminated MgB 2 nanosheets. We further discuss application-relevant implications, with a particular view towards understanding the impact of boron surface heterogeneity on hydrogen storage performance. Layered boron compounds attract enormous interest in applications. This work reports first-principles calculations coupled with global optimization to show that the outer boron surface in MgB 2 nanosheets undergo disordering and clustering, which is experimentally confirmed in synthesized MgB 2 nanosheets.

The compounds AlMgB14, AlLiB14 and MgMgB14 belong to the same space group, Imma, and share similar structural properties. It is predicted that the rigid band model accurately describes the electronic states of these orthorhombic borides. The position of the Fermi level within the states depends on the metal site constituency. In this work the electronic properties of each compound are studied in detail by ab initio methods. Löwdin population analysis is conducted to examine the local charge distribution, and the projected density of states is calculated. It is found that the valence band edge is strongly dominated by the \"Binter\" and \"Bconnector\" atoms. This indicates that moving the Fermi level into the valence band will result in changes to the local bonding between the icosahedra and the inter-icosahedra B atoms.

The cathode–electrolyte interphase plays a pivotal role in determining the usable capacity and cycling stability of electrochemical cells, yet it is overshadowed by its counterpart, the solid–electrolyte interphase. This is primarily due to the prevalence of side reactions, particularly at low potentials on the negative electrode, especially in state-of-the-art Li-ion batteries where the charge cutoff voltage is limited. However, as the quest for high-energy battery technologies intensifies, there is a pressing need to advance the study of cathode–electrolyte interphase properties. Here, we present a comprehensive approach to analyse the cathode–electrolyte interphase in battery systems. We underscore the importance of employing model cathode materials and coin cell protocols to establish baseline performance. Additionally, we delve into the factors behind the inconsistent and occasionally controversial findings related to the cathode–electrolyte interphase. We also address the challenges and opportunities in characterizing and simulating the cathode–electrolyte interphase, offering potential solutions to enhance its relevance to real-world applications. The cathode–electrolyte interphase (CEI) is vital for battery cell capacity and stability but receives less attention than the solid–electrolyte interphase. The authors review CEI properties, emphasize using model cathode materials and coin cell protocols, and address challenges and opportunities in characterizing and simulating CEI for real-world applications.

The process of carbon capture and sequestration has been proposed as a method of mitigating the build-up of greenhouse gases in the atmosphere. If implemented, the cost of electricity generated by a fossil fuel-burning power plant would rise substantially, owing to the expense of removing C[O.sub.2] from the effluent stream. There is therefore an urgent need for more efficient gas separation technologies, such as those potentially offered by advanced solid adsorbents. Here we show that diamine-appended metal-organic frameworks can behave as 'phase-change' adsorbents, with unusual step-shaped C[O.sub.2] adsorption isotherms that shift markedly with temperature. Results from spectroscopic, diffraction and computational studies show that the origin of the sharp adsorption step is an unprecedented cooperative process in which, above a metal-dependent threshold pressure, C[O.sub.2] molecules insert into metal-amine bonds, inducing a reorganization of the amines into well-ordered chains of ammonium carbamate. As a consequence, large C[O.sub.2] separation capacities can be achieved with small temperature swings, and regeneration energies appreciably lower than achievable with state-of-the-art aqueous amine solutions become feasible. The results provide a mechanistic framework for designing highly efficient adsorbents for removing C[O.sub.2] from various gas mixtures, and yield insights into the conservation of [Mg.sup.2+] within the ribulose-1,5-bisphosphate carboxylase/oxygenase family of enzymes.

The compounds AlMgB sub(14), AlLiB sub(14) and MgMgB sub(14) belong to the same space group, Imma, and share similar structural properties. It is predicted that the rigid band model accurately describes the electronic states of these orthorhombic borides. The position of the Fermi level within the states depends on the metal site constituency. In this work the electronic properties of each compound are studied in detail by ab initio methods. Lowdin population analysis is conducted to examine the local charge distribution, and the projected density of states is calculated. It is found that the valence band edge is strongly dominated by the \"B-\"t sub(er)\" and \"B sub()connector atoms. This indicates that moving the Fermi level into the valence band will result in changes to the local bonding between the icosahedra and the inter-icosahedra B atoms.