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Item type:Publication, Access status: without files , Light tuning CO/H2 composition on Ag: unraveling CO2 mass transfer and electron-phonon coupling in plasmon-enhanced electrocatalysisPlasmon-enhanced electrocatalysis (PEEC) is an emerging approach to mitigate CO2 emissions. The mechanisms behind CO2 adsorption and reduction at the catalyst–electrolyte interface in PEEC still need to be further explored. Herein, we employ a well-defined Ag nanostructure to elucidate these pivotal issues. By shining light with wavelengths of 625, 525, 405 nm on Ag, an adjustable CO/H2 ratio from 35 to 1 can be obtained. The reaction pathway changing under plasmonic excitation does not originate from the lowered CO2 mass transfer in the vicinity of Ag, as the electrochemical quartz crystal microbalance results unravel that a slightly elevated temperature in bulk electrolyte caused by light irradiation cannot weaken the CO2 adsorption at the Ag catalyst–electrolyte interface. Theoretical calculations reveal that optical excitation towards shorter wavelengths leads to a progressive lowered energy barrier for H2 formation together with an enhanced energy barrier for *COOH formation. Although thermodynamically suppressed, CO2 reduction can still be improved kinetically by optimizing the excitation wavelength and intensity, being accompanied with the enhanced photocurrent. Transient absorption spectroscopy results further correlate the higher photocurrent with a prolonged electron-phonon coupling time, verifying that the improvement of CO2 reduction kinetics in PEEC can be realized by hot electron harnessing.Publicationtype: Journal Article12 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Laser-generated high entropy metallic glass nanoparticles as bifunctional electrocatalystsHigh entropy metallic glass nanoparticles (HEMG NPs) are very promising materials for energy conversion due to the wide tuning possibilities of electrochemical potentials offered by their multimetallic character combined with an amorphous structure. Up until now, the generation of these HEMG NPs involved tedious synthesis procedures where the generated particles were only available on highly specialized supports, which limited their widespread use. Hence, more flexible synthetic approaches to obtain colloidal HEMG NPs for applications in energy conversion and storage are highly desirable. We utilized pulsed laser ablation of bulk high entropy alloy targets in acetonitrile to generate colloidal carbon-coated CrCoFeNiMn and CrCoFeNiMnMo HEMG NPs. An in-depth analysis of the structure and elemental distribution of the obtained nanoparticles down to single-particle levels using advanced transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) methods revealed amorphous quinary and senary alloy phases with slight manganese oxide/hydroxide surface segregation, which were stabilized within graphitic shells. Studies on the catalytic activity of the corresponding carbon-HEMG NPs during oxygen evolution and oxygen reduction reactions revealed an elevated activity upon the incorporation of moderate amounts of Mo into the amorphous alloy, probably due to the defect generation by atomic size mismatch. Furthermore, we demonstrate the superiority of these carbon-HEMG NPs over their crystalline analogies and highlight the suitability of these amorphous multi-elemental NPs in electrocatalytic energy conversion. [Figure not available: see fulltext.]Publicationtype: Journal ArticleScopus© Citations 37 99 240 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Nanoporous magnesium(2018-12-01); ; ; ; In this study, we present freestanding nanoporous magnesium as a novel lightweight material with high potential for structural and functional applications. Thus far, the high reactivity of Mg with oxygen and aqueous media prevented the fabrication of nanoporous Mg. First, in order to synthesize nanoporous Mg, we fabricated a bicontinuous nanocomposite consisting of interpenetrating Mg and non-Mg phases by liquid metal dealloying. The non-Mg phases in the nanocomposite protect Mg against corrosion. Second, we etched the non-Mg phases from the nanocomposite, leaving nanoporous Mg, using HF solution. This process is advantageous because the nanoporous Mg was passivated by a MgF2 layer during the etching. Our approach is very flexible, and we demonstrate that versatile microstructures of the nanoporous Mg—e.g., nanoscale bicontinuous network, hierarchical, or plate-like structures—can be designed for the given needs. More importantly, these nanoporous Mg samples can readily be exposed to air without being harmed by corrosion. [Figure not available: see fulltext.].Publicationtype: Journal Article97