| 1. |
- Borup, Anders Bæk, et al.
(författare)
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Unveiling the formation mechanism of PbxPdy intermetallic phases in solvothermal synthesis using in situ X-ray total scattering
- 2023
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Ingår i: Nanoscale. - 2040-3364. ; 15:45, s. 18481-18488
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Tidskriftsartikel (refereegranskat)abstract
- Pd possesses attractive catalytic properties and nano-structuring is an obvious way to enhance catalytic activity. Alloying Pd with Pb has been shown to enhance the catalytic effect of alcohol oxidation. Further optimization of the catalytic effect can be accomplished by controlling the particle size and key to this is understanding the formation mechanism. By monitoring solvothermal syntheses using in situ X-ray total scattering, this study unveils the formation mechanism of PbxPdy intermetallic nanoparticles. The formation occurs through a multi-step mechanism. Initially, Pd nanoparticles are formed, followed by incorporation of Pb into the Pd-structure, thus forming PbxPdy intermetallic nanoparticles. By varying the reaction time and temperature, the incorporation of Pb can be controlled, thereby tailoring the phase outcome. Based on the in situ solvothermal syntheses, ex situ autoclave syntheses were performed, resulting in the synthesis of Pb3Pd5 and Pb9Pd13 with a purity above 93%. The catalytic effect of these intermetallic phases towards the hydrogen evolution reaction (HER) is assessed. It is found that Pd, Pb3Pd5, and Pb9Pd13 have comparable stabilities, however, the overpotential increases with increasing amounts of Pb.
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| 2. |
- Hansen, Teis, et al.
(författare)
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Path creation in Nordic energy and road transport systems – the role of technological characteristics
- 2017
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Ingår i: Renewable & Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321. ; 70, s. 551-562
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews path-creation processes in road transport systems in the Nordic countries: e-mobility in Denmark, hydrogen and fuel-cell electrical vehicles in Norway, and advanced biofuels in Finland and Sweden. The study builds on the path creation literature, which seeks to explain the emergence of new technological pathways. Drawing on recent insights concerning the differences between design- and manufacturing-intensive technologies, the paper analyses the influence of technological characteristics on path creation processes. The case comparison indicates that technological characteristics seem to have greater influence on the content of activities in the later phase rather than the early phase of path creation processes. The analysis also emphasises that barriers to path creation processes differ depending on technological characteristics. This highlights the importance of considering technological characteristics in energy and transport policies.
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| 3. |
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| 4. |
- Zhang, Jiawei, et al.
(författare)
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New Insight on Tuning Electrical Transport Properties via Chalcogen Doping in n-type Mg3Sb2-Based Thermoelectric Materials
- 2018
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6832. ; 8:16
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Tidskriftsartikel (refereegranskat)abstract
- n-type Mg3Sb1.5Bi0.5 has recently been discovered to be a promising thermoelectric material, yet the effective n-type dopants are mainly limited to the chalcogens. This may be attributed to the limited chemical insight into the effects from different n-type dopants. By comparing the effects of different chalcogen dopants Q (Q = S, Se, and Te) on thermoelectric properties, it is found that the chalcogen dopants Q become more efficient with decreasing electronegativity difference between Q and Mg, which is mainly due to the increasing carrier concentration and mobility. Using density functional theory calculations, it is shown that the improving carrier concentration originates from the increasing doping limit induced by the stabilizing extrinsic defect. Moreover, the increasing electron mobility with decreasing electronegativity difference between Q and Mg is attributed to the smaller effective mass resulting from the enhancing chemical bond covalency, which is supported by the decreasing theoretical density of states. According to the above trends, a simple guiding principle based on electronegativity is proposed to shed new light on n-type doping in Zintl antimonides.
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