Change search
Refine search result
1 - 2 of 2
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Iakunkov, Artem
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Skrypnychuk, Vasyl
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nordenström, Andreas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shilayeva, Elizaveta A.
    Korobov, Mikhail
    Prodana, Mariana
    Enachescu, Marius
    Larsson, Sylvia H.
    Talyzin, Aleksandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Activated graphene as a material for supercapacitor electrodes: effects of surface area, pore size distribution and hydrophilicity2019In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084Article in journal (Refereed)
    Abstract [en]

    Activated reduced graphene oxide (a-rGO) is a material with a rigid 3D porous structure and high specific surface area (SSA). Using variation of activation parameters and post-synthesis mechanical treatment we prepared two sets of materials with a broad range of BET (N2) SSA ∼1000–3000 m2 g−1, and significant differences in pore size distribution and oxygen content. The performance of activated graphene as an electrode in a supercapacitor with KOH electrolyte was correlated with the structural parameters of the materials and water sorption properties. a-rGO is a hydrophobic material as evidenced by the negligibly small BET (H2O) SSA determined using analysis of water vapor sorption isotherms. However, the total pore volume determined using water vapor sorption and sorption of liquid water is almost the same as the one found by analysis of nitrogen sorption isotherms. Ball milling is found to provide an improved bulk density of activated graphene and collapse of all pores except the smallest ones (<2 nm). A decrease in the activation temperature from 850 °C to 550 °C is found to result in materials with a narrow micropore size distribution and increased oxygen content. Elimination of mesopores using ball milling or a lower activation temperature provided materials with better specific capacitance despite a significant decrease (by ∼30%) of the BET (N2) SSA. The best gravimetric and volumetric capacitances in KOH electrolyte were achieved not for samples with the highest value of the BET (N2) SSA but for materials with 80–90% of the total pore volume in micropores and an increased BET (H2O) SSA. Comparing the performance of electrodes prepared using rGO and a-rGO shows that a more hydrophilic surface is favorable for charge storage in supercapacitors with KOH electrolyte.

  • 2.
    Zäll, Erik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nordenström, Andreas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Mossegård, Jonatan
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Electroplating of selective surfaces for concentrating solar collectors2018In: PROCEEDINGS OF THE ISES EUROSUN 2018 CONFERENCE - 12TH INTERNATIONAL CONFERENCE ON SOLAR ENERGY FOR BUILDINGS AND INDUSTRY / [ed] Haberle, A, International Solar Energy Society, 2018, p. 1086-1095Conference paper (Refereed)
    Abstract [en]

    A spectrally selective surface is produced by electrodeposition of a Co-Cr coating on a stainless steel substrate. The plating bath consisted of CrCl3 center dot 6H(2)O and CoCl2 center dot 6H(2)O dissolved in a deep eutectic solvent (DES) of choline chloride and ethylene glycol. This DES enables the use of trivalent (Cr(III)) instead of hexavalent chromium (Cr(XI)) which significantly reduces health risks associated with chromium electroplating. The selective surface exhibits an absorptance (alpha) of 0.96 and an emittance (epsilon) of 0.13 at 100 degrees C making it well adapted for mid- to lowtemperature concentrating solar collectors. The 1.8 mu m thick coating exhibits a porous structure on the surface as well as throughout the entire coating. The surface of the coating comprises of Co oxides and hydroxides, while the bulk consists of metallic and oxidized Co and only small fractions of Cr compounds. Initial tests of the thermal stability indicate that the coating does not maintain optical properties at an acceptable level over a lifetime of 25 years. At approximately 438 degrees C significant parts of the coating is oxidized in an oxygen rich environment.

1 - 2 of 2
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf