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- Annamalai, Alagappan, et al.
(författare)
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Influence of Sb5+ as a Double Donor on Hematite (Fe3+) Photoanodes for Surface-Enhanced Photoelectrochemical Water Oxidation
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:19, s. 16467-16473
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Tidskriftsartikel (refereegranskat)abstract
- To exploit the full potential of hematite (α-Fe2O3) as an efficient photoanode for water oxidation, the redox processes occurring at the Fe2O3/electrolyte interface need to be studied in greater detail. Ex situ doping is an excellent technique to introduce dopants onto the photoanode surface and to modify the photoanode/electrolyte interface. In this context, we selected antimony (Sb5+) as the ex situ dopant because it is an effective electron donor and reduces recombination effects and concurrently utilize the possibility to tuning the surface charge and wettability. In the presence of Sb5+ states in Sb-doped Fe2O3 photoanodes, as confirmed by X-ray photoelectron spectroscopy, we observed a 10-fold increase in carrier concentration (1.1 × 1020 vs 1.3 × 1019 cm–3) and decreased photoanode/electrolyte charge transfer resistance (∼990 vs ∼3700 Ω). Furthermore, a broad range of surface characterization techniques such as Fourier-transform infrared spectroscopy, ζ-potential, and contact angle measurements reveal that changes in the surface hydroxyl groups following the ex situ doping also have an effect on the water splitting capability. Theoretical calculations suggest that Sb5+ can activate multiple Fe3+ ions simultaneously, in addition to increasing the surface charge and enhancing the electron/hole transport properties. To a greater extent, the Sb5+- surface-doped determines the interfacial properties of electrochemical charge transfer, leading to an efficient water oxidation mechanism.
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- Ekspong, Joakim, et al.
(författare)
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Stable Sulfur‐Intercalated 1T′ MoS2 on Graphitic Nanoribbons as Hydrogen Evolution Electrocatalyst
- 2018
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Ingår i: Advanced Functional Materials. - : WILEY-VCH VERLAG GMBH. - 1616-301X .- 1616-3028. ; 28:46
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Tidskriftsartikel (refereegranskat)abstract
- The metastable 1T′ polymorph of molybdenum disulfide (MoS2) has shown excellent catalytic activity toward the hydrogen evolution reaction (HER) in water‐splitting applications. Its basal plane exhibits high catalytic activity comparable to the edges in 2H MoS2 and noble metal platinum. However, the production and application of this polymorph are limited by its lower energetic stability compared to the semiconducting 2H MoS2 phase. Here, the production of stable intercalated 1T′ MoS2 nanosheets attached on graphitic nanoribbons is reported. The intercalated 1T′ MoS2 exhibits a stoichiometric S:Mo ratio of 2.3 (±0.1):1 with an expanded interlayer distance of 10 Å caused by a sulfur‐rich intercalation agent and is stable at room temperature for several months even after drying. The composition, structure, and catalytic activity toward HER are investigated both experimentally and theoretically. It is concluded that the 1T′ MoS2 phase is stabilized by the intercalated agents, which further improves the basal planes′ catalytic activity toward HER.
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- Geissinger, Andrea, 1987-
(författare)
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Platforms in Liquid Modernity : Essays about the Sharing Economy, Digital Platforms, and Institutions
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The year 2020 feels like the beginning of a crescendo of change. As environmental and social challenges reach an all-time high, the organization of our societies is coming under scrutiny. We, as a society, turn to technology to reinvent the organization of social life after disruptive episodes. Inspired by Bauman's theorizing to describe the cultural and societal zeitgeist, this thesis explains the institutionalization of one of the most promising alternative forms of organization of the past decade: the sharing economy.Comprised of nine essays centered around three focal areas: (1) Organizational change, (2) Market change, and (3) Societal change, this thesis aims to explain the institutionalization of digital sharing platforms in liquid modern society.This thesis finds that digital sharing platforms act as societal organizers on several dimensions of “in-betweenness.” As this moment in time can also be characterized as a period of “interregnum”—another moment of in-betweenness—where old structures are continuously disrupted but no clear new path has emerged, digital platform providers fill a structural void in our highly individualized society. Digital platform providers use community as an anchor, a belief, and sets of practices to create an emerging (intermediary) institution around which different forms of organization manifest.Digital sharing platforms have, however, remained a grace note on systemic change: ornamental and practically non-essential. Still, digital platforms are setting new norms in all areas of organizational, market, and societal life. By evoking both elements of community and market, digital platforms are playing an important part in creating a symphony of our future societal order.
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- Gustafsson, Robin, et al.
(författare)
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Towards an Integrative Digital History Approach in Organization Studies
- 2016
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Ingår i: Academy of Management Proceedings. - : Academy of Management.
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Konferensbidrag (refereegranskat)abstract
- Recent developments in digitizing of historical data and advances in software tools for structured analysis of digitized historical data, are creating opportunities to unleash previously untapped ways to use historical data. We build on recent suggestions for methodological integration, for outlining an integrative digital history approach, with the methodological rigor to unleash creative synthesis of business history and organization studies. Methodological integration constitutes an inter-meshing of methods that takes place already from the outset of the research process and remains so throughout the collection of sources, interpretation, and analysis. This places at the center a careful research design with a relational database for the collection and digitizing of data, structuring and coding of historical sources, historical interpretation, and analytics to be used. We outline key design issues, steps and processes for an integrative digital history approach. Following, we present the strengths of this approach in comparison to existing ‘analog’ business history and organizational studies methods. We end the paper by discussing future avenues and opportunities for digital history.
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- Hu, Guangzhi, et al.
(författare)
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Atomistic understanding of the origin of high oxygen reduction electrocatalytic activity of cuboctahedral Pt3Co-Pt core-shell nanoparticles
- 2016
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Ingår i: Catalysis Science & Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 6:5, s. 1393-1401
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Tidskriftsartikel (refereegranskat)abstract
- PtM-based core-shell nanoparticles are a new class of active and stable nanocatalysts for promoting oxygen reduction reaction (ORR); however, the understanding of their high electrocatalytic performance for ORR at the atomistic level is still a great challenge. Herein, we report the synthesis of highly ordered and homogeneous truncated cuboctahedral Pt3Co-Pt core-shell nanoparticles (cs-Pt3Co). By combining atomic resolution electron microscopy, X-ray photoelectron spectroscopy, extensive first-principles calculations, and many other characterization techniques, we conclude that the cs-Pt3Co nanoparticles are composed of a complete or nearly complete Pt monolayer skin, followed by a secondary shell containing 5-6 layers with similar to 78 at% of Pt, in a Pt3Co configuration, and finally a Co-rich core with 64 at% of Pt. Only this particular structure is consistent with the very high electrocatalytic activity of cs-Pt3Co nanoparticles for ORR, which is about 6 times higher than commercial 30%-Pt/Vulcan and 5 times more active than non-faceted (spherical) alloy Pt3Co nanoparticles. Our study gives an important insight into the atomistic design and understanding of advanced bimetallic nanoparticles for ORR catalysis and other important industrial catalytic applications.
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- Hunter, Amanda, et al.
(författare)
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Effect of wood smoke exposure on vascular function and thrombus formation in healthy fire fighters
- 2014
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Ingår i: Particle and Fibre Toxicology. - : BioMed Central (BMC). - 1743-8977. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Myocardial infarction is the leading cause of death in fire fighters and has been linked with exposure to air pollution and fire suppression duties. We therefore investigated the effects of wood smoke exposure on vascular vasomotor and fibrinolytic function, and thrombus formation in healthy fire fighters. Methods: In a double-blind randomized cross-over study, 16 healthy male fire fighters were exposed to wood smoke (~1 mg/m3 particulate matter concentration) or filtered air for one hour during intermittent exercise. Arterial pressure and stiffness were measured before and immediately after exposure, and forearm blood flow was measured during intra-brachial infusion of endothelium-dependent and -independent vasodilators 4–6 hours after exposure. Thrombus formation was assessed using the ex vivo Badimon chamber at 2 hours, and platelet activation was measured using flow cytometry for up to 24 hours after the exposure. Results: Compared to filtered air, exposure to wood smoke increased blood carboxyhaemoglobin concentrations (1.3% versus 0.8%; P < 0.001), but had no effect on arterial pressure, augmentation index or pulse wave velocity (P > 0.05 for all). Whilst there was a dose-dependent increase in forearm blood flow with each vasodilator (P < 0.01 for all), there were no differences in blood flow responses to acetylcholine, sodium nitroprusside or verapamil between exposures (P > 0.05 for all). Following exposure to wood smoke, vasodilatation to bradykinin increased (P = 0.003), but there was no effect on bradykinin-induced tissue-plasminogen activator release, thrombus area or markers of platelet activation (P > 0.05 for all). Conclusions: Wood smoke exposure does not impair vascular vasomotor or fibrinolytic function, or increase thrombus formation in fire fighters. Acute cardiovascular events following fire suppression may be precipitated by exposure to other air pollutants or through other mechanisms, such as strenuous physical exertion and dehydration.
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