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Item type:Publication, Access status: with files , MnTiO₃ as a carbon-free cathode for rechargeable Li–O₂ batteries(Royal Society of Chemistry (RSC), 2025-01-17); ; ; ; Li-O2 batteries (LOBs) are next-generation energy storage systems. However, their main challenges are the sluggish kinetics of oxygen reduction and evolution reactions (ORR/OER) and high charge overpotentials due to the formation of discharge product (Li2O2). To address this challenge, developing a catalyst with a unique structure and exceptional catalytic properties is crucial to enhancing the reversible cycling performance of LOBs, particularly under high current density conditions. Herein, the transition metal-based perovskite MnTiO3 was examined as a carbon-free cathode catalyst using density functional theory (DFT) calculations and experimental techniques. The intrinsic advantages of MnTiO3 stem from the coexistence of Mn and Ti energy levels near the Fermi level, as revealed by our density of states (DOS) analysis. This electronic structure facilitates ORR/OER, thus endowing MnTiO3 with a bifunctional role in promoting battery performance. Our DFT-based investigation elucidates the surface stability and catalytic properties of MnTiO3. Furthermore, Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) confirm that the electrochemical reaction on MnTiO3 follows a two-electron pathway. Our findings reveal that a LOB with MnTiO3 exhibits a total overpotential of 1.18 V and 1.55 V using DFT and electrochemical measurements, respectively. High current densities up to 1 A g−1 also highlight its potential as a cathode catalyst for LOBs.Publicationtype: Journal Article22 22 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Data-driven selection of electrolyte additives for aqueous magnesium batteries(2022-09-23); ; ; ; Aqueous primary Mg-air batteries have considerable potential as energy sources for sea applications and portable devices. However, some challenges at the anode-electrolyte interface related to self-corrosion, aging of the electrolyte and the chunk-effect have to be solved to improve the discharge potential of the battery as well as the utilization efficiency of the anode material. Aside from alloying, an effective strategy to mitigate self-corrosion and battery failure is the use of electrolyte additives. Selecting useful additives from the vast chemical space of possible compounds is not a trivial task. Fortunately, data-driven quantitative structure-property relationship (QSPR) models can facilitate efficient searches for promising battery booster candidates. Here, the robustness and predictive performance of two QSPR models are evaluated using an active design of experiments approach. We also present a multi-objective optimization method that allows to identify new electrolyte additives that can boost the battery anode performance with respect to a target application, thus accelerating the discovery of advanced battery systems.Publicationtype: Journal Article88 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Oxygen exchange kinetics on systematically doped ceria : a pulsed isotope exchange studyThe importance of point defects for oxygen surface reaction kinetics on doped ceria is demonstrated by pulsed isotope exchange. The oxygen surface exchange reaction on 20 different Gd/Pr/Tb, and Nb single and co-doped ceria samples is studied from 500-850 °C in 10-0.1% O2 atmosphere. The highest rates are measured when both oxygen vacancies and redox-active centers are available. Gd-doping leads to exchange rates which are proportional to the concentrations of Gd and oxygen vacancies. Pr-doped ceria exhibits a much stronger variation of the exchange rate-by almost five orders of magnitude from 0.6 to 20 mol% Pr doping-emphasizing the importance of redox-active centers. The equilibrium exchange rates are low for Nb, Nb/Pr, and Nb/Gd co-doped ceria, emphasizing the important role of oxygen vacancies for oxygen dissociation and incorporation. The oxygen partial pressure dependence indicates that molecular oxygen species are involved in the rate-determining step (in addition to oxygen vacancies).Publicationtype: Journal Article9 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Low powered, tunable and ultra-light aerographite sensor for climate relevant gas monitoring(Royal Society of Chemistry (RSC), 2016-09-27); ; ; ; Increasing atmospheric CO2 gas pollution and emergence of new types of green energy sources require continuous environmental monitoring. In this context, fast, efficient, light, robust, and reliable gas sensors that can work at room temperature are in high demand. We report on a low-powered type of ultra-light sensor, based on a 3-D-microtube network from a 2-D graphene/nanographite, called aerographite, and a method to tune the nanosensor’s selectivity by a simple variation of the applied bias voltage. Adequate selectivity to CO2 and ultra-fast sensing of H2 by applying 1 V and 5 V, respectively, is obtained. At ultra-low applied bias voltages (1–100 mV) only very low power consumption (z3.6 nW for 1 mV) is needed. This is most important, as it can be run by energy harvesting methods. The presented results are of the highest interest in terms of low-cost production of ultra-light and ultra-low-power consumption gas sensors for environmental monitoring of greenhouse gases and their simplicity from the technological/engineering points of view.Publicationtype: Journal ArticleScopus© Citations 49 388 420 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Nanostructural changes in crystallizable controlling units determine the temperature-memory of polymers(Royal Society of Chemistry (RSC), 2015-03-03); ; ; ; Temperature-memory polymers remember the temperature, where they were deformed recently, enabled by broad thermal transitions. In this study, we explored a series of crosslinked poly[ethylene-co-(vinyl acetate)] networks (cPEVAs) comprising crystallizable polyethylene (PE) controlling units exhibiting a pronounced temperature-memory effect (TME) between 16 and 99 °C related to a broad melting transition (∼100 °C). The nanostructural changes in such cPEVAs during programming and activation of the TME were analyzed via in situ X-ray scattering and specific annealing experiments. Different contributions to the mechanism of memorizing high or low deformation temperatures (Tdeform) were observed in cPEVA, which can be associated to the average PE crystal sizes. At high deformation temperatures (>50 °C), newly formed PE crystals, which are established during cooling when fixing the temporary shape, dominated the TME mechanism. In contrast, at low Tdeform (<50 °C), corresponding to a cold drawing scenario, the deformation led preferably to a disruption of existing large crystals into smaller ones, which then fix the temporary shape upon cooling. The observed mechanism of memorizing a deformation temperature might enable the prediction of the TME behavior and the knowledge based design of other TMPs with crystallizable controlling units.Publicationtype: Journal ArticleScopus© Citations 17 367 214 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Correlating surface cation composition and thin film microstructure with the electrochemical performance of lanthanum strontium cobaltite (LSC) electrodes(Royal Society of Chemistry (RSC), 2014-02-26); ; ; ; La0.6Sr0.4CoO3-δ thin films of varying thicknesses (20-170 nm) were prepared by pulsed laser deposition on yttria-stabilized zirconia (100) substrates, and their electrochemical electrode performance was correlated with the chemical surface composition and microstructure (e.g. porosity, surface area). The surface cation composition was analyzed by an atomic etching procedure with on-line inductively coupled plasma optical emission spectrometry detection. The surface sensitivity of the method was increased by dynamically switching the etching reagent during the on-line analysis and quantitative results for even the top atomic layer were obtained. A water-soluble Sr-rich surface species could be quantified on top of the LSC films and in combination with electrochemical analysis of the films by impedance spectroscopy an improved understanding of the surface exchange resistance could be obtained. Microstructural features such as the effective porosity of the films became accessible by a combination of these methods.Publicationtype: Journal ArticleScopus© Citations 52 75 121