| 1. |
- Abi Ghaida, Fatima, et al.
(författare)
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Enzymatic N2 activation : general discussion
- 2023
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Ingår i: Faraday discussions. - : Royal Society of Chemistry. - 1359-6640 .- 1364-5498. ; 243, s. 287-295
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 2. |
- Lindahl, Niklas, 1981, et al.
(författare)
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High Specific and Mass Activity for the Oxygen Reduction Reaction for Thin Film Catalysts of Sputtered Pt3Y
- 2017
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Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 4:13
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Tidskriftsartikel (refereegranskat)abstract
- Fuel cells have the potential to play an important role in sustainable energy systems, provided that catalysts with higher activity and stability are developed. In this work, it is found that thin alloy films of single-target cosputtered platinum-yttrium exhibit up to seven times higher specific activity (13.4 +/- 0.4 mA cm(-2)) for the oxygen reduction reaction (ORR) than poly-crystalline platinum, and up to one order of magnitude higher mass activity (3.5 +/- 0.3 A mg(-1)) than platinum nanoparticles. These alloys have the highest reported ORR activity for an as-deposited material, i.e., without any additional chemical or thermal treatment. The films show an improvement in stability over the same materials in nanoparticulate form. Physical characterization shows that the thin films form a platinum overlayer supported on an underlying alloy. The high activity is likely related to compressive strain in that overlayer. As sputtering can be used to mass-produce fuel cell electrodes, the results open new possibilities for the preparation of platinum-rare earth metal alloy catalysts in commercial devices.
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| 3. |
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| 4. |
- Frydendal, Rasmus, et al.
(författare)
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Benchmarking the Stability of Oxygen Evolution Reaction Catalysts: The Importance of Monitoring Mass Losses
- 2014
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Ingår i: ChemElectroChem. - : Wiley. - 2196-0216. ; 1:12, s. 2075-2081
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Tidskriftsartikel (refereegranskat)abstract
- Because of the rising need for energy storage, potentially facilitatedby electrolyzers, improvements to the catalysis of theoxygen evolution reaction (OER) become increasingly relevant.Standardized protocols have been developed for determiningcritical figures of merit, such as the electrochemical surfacearea, mass activity and specific activity. Even so, when new andmore active catalysts are reported, the catalyst stability tendsto play a minor role. In this work, we monitor corrosion onRuO2 and MnOx by combining the electrochemical quartz crystalmicrobalance (EQCM) with inductively coupled plasma massspectrometry (ICP–MS). We show that a meaningful estimationof the stability cannot be achieved based on purely electrochemicaltests. On the catalysts tested, the anodic dissolutioncurrent was four orders of magnitude lower than the total current.We propose that even if long-term testing cannot be replaced,a useful evaluation of the stability can be achievedwith short-term tests by using EQCM or ICP–MS.
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| 5. |
- Palacin, M. R., et al.
(författare)
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Roadmap on multivalent batteries
- 2024
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Ingår i: JPhys Energy. - 2515-7655. ; 6:3
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Forskningsöversikt (refereegranskat)abstract
- Battery technologies based in multivalent charge carriers with ideally two or three electrons transferred per ion exchanged between the electrodes have large promises in raw performance numbers, most often expressed as high energy density, and are also ideally based on raw materials that are widely abundant and less expensive. Yet, these are still globally in their infancy, with some concepts (e.g. Mg metal) being more technologically mature. The challenges to address are derived on one side from the highly polarizing nature of multivalent ions when compared to single valent concepts such as Li+ or Na+ present in Li-ion or Na-ion batteries, and on the other, from the difficulties in achieving efficient metal plating/stripping (which remains the holy grail for lithium). Nonetheless, research performed to date has given some fruits and a clearer view of the challenges ahead. These include technological topics (production of thin and ductile metal foil anodes) but also chemical aspects (electrolytes with high conductivity enabling efficient plating/stripping) or high-capacity cathodes with suitable kinetics (better inorganic hosts for intercalation of such highly polarizable multivalent ions). This roadmap provides an extensive review by experts in the different technologies, which exhibit similarities but also striking differences, of the current state of the art in 2023 and the research directions and strategies currently underway to develop multivalent batteries. The aim is to provide an opinion with respect to the current challenges, potential bottlenecks, and also emerging opportunities for their practical deployment.
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| 6. |
- Pedersen, Anders F., et al.
(författare)
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Operando XAS Study of the Surface Oxidation State on a Monolayer IrOx, on RuOx and Ru Oxide Based Nanoparticles for Oxygen Evolution in Acidic Media
- 2018
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 122:2, s. 878-887
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Tidskriftsartikel (refereegranskat)abstract
- Herein we present surface sensitive operando XAS L-edge measurements on IrOx/RuO2 thin films as well as mass-selected RuOx and Ru nanoparticles. We observed shifts of the white line XAS peak toward higher energies with applied electrochemical potential. Apart from the case of the metallic Ru nanoparticles, the observed potential dependencies were purely core-level shifts caused by a change in oxidation state, which indicates no structural changes. These findings can be explained by different binding energies of oxygenated species on the surface of IrOx and RuOx. Simulated XAS spectra show that the average Ir oxidation state change is strongly affected by the coverage of atomic O. The observed shifts in oxidation state suggest that the surface has a high coverage of O at potentials just below the potential where oxygen evolution is exergonic in free energy. This observation is consistent with the notion that the metal-oxygen bond is stronger than ideal.
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| 7. |
- Siahrostami, Samira, 1982, et al.
(författare)
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Enabling direct H2O2 production through rational electrocatalyst design
- 2013
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 12:12, s. 1137-1143
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Tidskriftsartikel (refereegranskat)abstract
- Future generations require more efficient and localized processes for energy conversion and chemical synthesis. The continuous on-site production of hydrogen peroxide would provide an attractive alternative to the present state-of-the-art, which is based on the complex anthraquinone process. The electrochemical reduction of oxygen to hydrogen peroxide is a particularly promising means of achieving this aim. However, it would require active, selective and stable materials to catalyse the reaction. Although progress has been made in this respect, further improvements through the development of new electrocatalysts are needed. Using density functional theory calculations, we identify Pt-Hg as a promising candidate. Electrochemical measurements on Pt-Hg nanoparticles show more than an order of magnitude improvement in mass activity, that is, Ag-1 precious metal, for H2O2 production, over the best performing catalysts in the literature.
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| 8. |
- Stoerzinger, Kelsey A., et al.
(författare)
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Orientation-Dependent Oxygen Evolution on RuO2 without Lattice Exchange
- 2017
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 2:4, s. 876-881
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Tidskriftsartikel (refereegranskat)abstract
- RuO2 catalysts exhibit record activities toward the oxygen evolution reaction (OER), which is crucial to enable efficient and sustainable energy storage. Here we examine the RuO2 OER kinetics on rutile (110), (100), (101), and (111) orientations, finding (100) the most active. We assess the potential involvement of lattice oxygen in the OER mechanism with online electrochemical mass spectrometry, which showed no evidence of oxygen exchange on these oriented facets in acidic or basic electrolytes. Similar results were obtained for polyoriented RuO2 films and particles, in contrast to previous work, suggesting lattice oxygen is not exchanged in catalyzing OER on crystalline RuO2 surfaces. This hypothesis is supported by the correlation of activity with the number of active Ru-sites calculated by density functional theory, where more active facets bind oxygen more weakly. This new understanding of the active sites provides a design strategy to enhance the OER activity of RuO2 nanoparticles by facet engineering.
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