On the correlation between the oxygen in hydrogen content and the catalytic activity of cathode catalysts in PEM water electrolysis

Altogether five platinum group metal (PGM) and PGM-free cathode catalysts were investigated in full PEM water electrolysis cells regarding their polarisation behaviour and their hydrogen and oxygen recombination properties. It was shown that the recombination activity of permeated oxygen and evolved hydrogen within the cathodic catalyst layer correlates with the activity of the oxygen reduction reaction (ORR) which was determined ex situ with linear sweep voltammetry. We found that the investigated PGM-free cathode catalysts had a low activity for the ORR resulting in higher measurable oxygen in hydrogen volume fractions compared to the PGM catalysts, which are more active for the ORR. Out of the three investigated PGM-free catalysts, only one commercially available material based on a Ti suboxide showed a similar good polarisation behaviour as the state of the art cathode catalyst platinum, while its recombination activity was the lowest of all catalysts. In addition to the recombination of hydrogen and oxygen on the electrocatalysts, we found that the prevalent carbon-based cathodic porous transport layers (PTL) also offer catalytically active recombination sites. In comparison to an inactive PTL, the measurable oxygen flux using carbon-based PTLs was lower and the recombination was enhanced by microporous coatings with high surface areas. © 2021 The Author(s)

On the Correlation between the Oxygen in Hydrogen Content and the Catalytic Activity of Cathode Catalysts in PEM Water Electrolysis

Altogether five platinum group metal (PGM) and PGM-free cathode catalysts were investigated in full PEM water electrolysis cells regarding their polarisation behaviour and their hydrogen and oxygen recombination properties. It was shown that the recombination activity of permeated oxygen and evolved hydrogen within the cathodic catalyst layer correlates with the activity of the oxygen reduction reaction (ORR) which was determined ex situ with linear sweep voltammetry. We found that the investigated PGM-free cathode catalysts had a low activity for the ORR resulting in higher measurable oxygen in hydrogen volume fractions compared to the PGM catalysts, which are more active for the ORR. Out of the three investigated PGM-free catalysts, only one commercially available material based on a Ti suboxide showed a similar good polarisation behaviour as the state of the art cathode catalyst platinum, while its recombination activity was the lowest of all catalysts. In addition to the recombination of hydrogen and oxygen on the electrocatalysts, we found that the prevalent carbon-based cathodic porous transport layers (PTL) also offer catalytically active recombination sites. In comparison to an inactive PTL, the measurable oxygen flux using carbon-based PTLs was lower and the recombination was enhanced by microporous coatings with high surface areas.BMBF, 03SF0536F, Verbundvorhaben PowerMEE: Lebensdauer- und Leistungserhöhung (POWER) von Polymerelektrolytmembranelektrolyseuren durch Hochleistungsmembranelektrodeneinheiten (MEE) - Teilprojekt: Herstellung von Membran Elektrodeneinheiten und tomographische Analys

Dissection of the Role of PfEMP1 and ICAM-1 in the Sensing of Plasmodium falciparum-Infected Erythrocytes by Natural Killer Cells

BACKGROUND: Host innate immunity contributes to malaria clinical outcome by providing protective inflammatory cytokines such as interferon-γ, and by shaping the adaptive immune response. Plasmodium falciparum (Pf) is the etiologic agent of the most severe forms of human malaria. Natural Killer (NK) cells are lymphocytes of the innate immune system that are the first effectors to produce interferon-γ in response to Pf. However, the molecular bases of Pf-NK cell recognition events are unknown. Our study focuses on the role of Pf erythrocyte membrane protein 1 (PfEMP1), a major Pf virulence factor. PfEMP1 is expressed on parasitized-erythrocytes and participates to vascular obstruction through the binding to several host receptors. PfEMP1 is also a pivotal target for host antibody response to Pf infection. METHODOLOGY/PRINCIPAL FINDINGS: Using genetically-engineered parasite mutant strains, a human genetic deficiency, and blocking antibodies, we identified two receptor-ligand pairs involved in two uncoupled events occurring during the sensing of Pf infection by NK cells. First, PfEMP1 interaction with one of its host receptor, chondroitin sulfate A, mediates the cytoadhesion of Pf-infected erythrocytes to human NK cell lines, but is not required for primary NK cell activation. Second, intercellular adhesion molecule-1 (ICAM-1), another host receptor for PfEMP1, is mandatory for NK cell interferon-γ response. In this case, ICAM-1 acts via its engagement with its host ligand, LFA-1, and not with PfEMP1, consistent with the obligatory cross-talk of NK cells with macrophages for their production of interferon-γ. CONCLUSION/SIGNIFICANCE: PfEMP1-independent but ICAM-1/LFA-1-dependent events occurring during NK cell activation by Pf highlight the fundamental role of cellular cooperation during innate immune response to malaria

Review of multi-BRP, aggregator settlement models at large-scale connections in the European electricity system

Developments in the electricity grid such as the integration of renewable energy and the deployment of electric transportation and heating will result in a more complex system with higher degree of uncertainty. An increasing role for flexibility can maintain the economic and technical functioning of this grid. Flexibility aggregators enhance the availability of flexibility, but can expose energy suppliers and their BRPs to risks when not subject to a proper market structure. In this paper, five settlement models to structure the interactions between energy suppliers, BRPs and aggregators are reviewed in the context of the European electricity market: the uncorrected, corrected, contractual, central settlement and the combined model

Review of multi-BRP, aggregator settlement models at large-scale connections in the European electricity system

Developments in the electricity grid such as the integration of renewable energy and the deployment of electric transportation and heating will result in a more complex system with higher degree of uncertainty. An increasing role for flexibility can maintain the economic and technical functioning of this grid. Flexibility aggregators enhance the availability of flexibility, but can expose energy suppliers and their BRPs to risks when not subject to a proper market structure. In this paper, five settlement models to structure the interactions between energy suppliers, BRPs and aggregators are reviewed in the context of the European electricity market: the uncorrected, corrected, contractual, central settlement and the combined model