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- AEM-Electrolysis (1)
- Electrodeposition (1)
- Elektrolyseure (1)
- Erneuerbare Energien (1)
- Hydraulic compression, Carbon Nano Fibers, PEM Fuel Cells, Catalyst utilization (1)
- Kohlenstoff-Nanoröhre (1)
- Membran-Elektroden-Einheit (1)
- Ni-Mo alloy Catalyst (1)
- PEM Electrolysis, Hydrogen, Hydraulic Compression, High Pressure (1)
- PEM fuel cells; electrode preparation; carbon nanofibers; in-situ performance test (1)
Membrane electrode assemblies (MEA) developed at the Westphalian Energy Institute for polymer electrolyte membrane fuel cells (PEMFC) are high tech systems containing various materials structured in nanoscale, at which electrochemical reactions occur on catalyst nano particle surfaces. For low reactance homogeneous compression of the MEA’s layers is necessary. A novel stack architecture for electrochemical cells, especially PEMFC as well as PEM electrolysers, has been developed according to achieve ideal cell operation conditions. Single cells of such a stack are inserted into flexible slots that are surrounded by hydraulic media. While operation the hydraulic media is pressurised which leads to an even compression and cooling of the stack’s cells. With this stack design it has been possible to construct a test facility for simultaneous characterisation of several MEA samples. As compression and temperature conditions of every single sample are equal, with the novel test system the effect of e.g. different electrode configurations can be investigated. Furthermore, the modular stack design leads to the development of hybrid energy applications combining fuel cells, electrolysers, batteries as well as metal hydride tanks in one system.
Various aqueous citrate electrolyte compositions for the Ni-Mo electrodeposition are explored in order to deposit Ni-Mo alloys with Mo-content ranging from 40 wt% to 65 wt% to find an alloy composition with superior catalytic activity towards the hydrogen evolution reaction (HER). The depositions were performed on copper substrates mounted onto a rotating disc electrode (RDE) and were investigated via scanning electron microscopy (SEM), X-ray fluorescence (XRF) and X-ray diffraction (XRD) methods as well as linear sweep voltammetry (LSV) and impedance spectroscopy. Kinetic parameters were calculated via Tafel analysis. Partial deposition current densities and current efficiencies were determined by correlating XRF measurements with gravimetric results. The variation of the electrolyte composition and deposition parameters enabled the deposition of alloys with Mo-content over the range of 40-65 wt%. An increase in Mo-content in deposited alloys was recorded with an increase in rotation speed of the RDE. Current efficiency of the deposition was in the magnitude of <1%, which is characteristic for the deposition of alloys with high Mo-content. The calculated kinetic parameters were used to determine the Mo-content with the highest catalytic activity for use in the HER.
Hochdruck PEM-Elektrolyse
(2017)
Im Rahmen eines gemeinsamen Forschungsprojekts mit dem Titel „Energieautarke Bohrlochsensorik mittels Brennstoffzellen – GeoFuelCells“ wurde vom Geothermie-Zentrum Bochum und dem Westfälischen Energieinstitut, unterstützt aus dem Förderprogramm Ziel 2 (2007-2013 EFRE) des Landes NRW, ein brennstoffzellenbasiertes Energieversorgungssystem für Bohrloch-Anwendungen entwickelt.
This work deals with the preparation and investigation of PEM fuel cell electrodes, which are obtained using graphene related material (GRM) serving as catalyst support for platinum nanoparticles. Applied GRM are used for the preparation of suspensions in four distinct mixing ratios. Two sorts of GRM have been investigated: carbon nanofibers (CNF) and graphene oxide (GO). Utilized CNFs provide a superior graphitization degree of about 100%, which leads to both high corrosion resistance and low ohmic resistance in PEM fuel cells.
For electrode preparation a GRM containing layer serving as catalyst support is applied onto a gas diffusion layer (GDL). Prior to GRM suspension and deposition onto a GDL, the graphene structures are functionalized by plasma treatment. Due to this step, an improved hydrophilic behavior for facilitating suspension preparation is achieved. In addition, a subsequent platinum nanoparticle deposition by pulsed electrodeposition process is optimized.
This experimental work deals with the preparation and investigation of PEM fuel cell electrodes, which are obtained using Graphene Related Material (GRM) serving as catalyst support material for platinum nanoparticles. The applied GRM belong to the group of carbon nanofibers and exhibits a helical-ribbon structure with dimensions of 50 nm in diameter and an average length up to a few µm. Furthermore, utilized GRM provide a superior graphitisation degree of about 100 %, which leads to both high corrosion resistance and low ohmic resistance. Material stability plays one of the main roles for long term fuel cell operation, whereby a great electrical catalyst contact combined with high specific surface area yields in high fuel cell performances.
Prior to GRM dispersion and deposition onto a gas diffusion layer, the graphene structures are functionalized by oxygen plasma treatment. Through this step, functional oxygen groups are generated onto the GRM outer surface providing an improved hydrophilic behaviour and facilitating the GRM suspension preparation. In addition, the oxygen groups act as anchors for platinum nanoparticles which are subsequently deposited onto the GRM surface through a pulse electrodeposition process.
Membrane electrode assemblies produced with the prepared electrodes are investigated in-situ in a PEM fuel cell test bench.