This work deals with the preparation and investigation of polymer electrolyte membrane fuel cell (PEMFC) electrodes, which are obtained using gas diffusion layers coated with graphene related material (GRM) serving as a catalyst support for platinum nanoparticles. PEMFC electrocatalysts have been prepared by pulsed electrochemical deposition of platinum particles from hexachloroplatinic acid. Prior to GRM decoration with platinum, the graphene structures are functionalized by oxygen plasma treatment. This leads to oxygen containing functional groups on the GRM outer surface, providing an improved hydrophilic behavior, thus favoring the Pt deposition process. Membrane electrode assemblies (MEAs) with the so prepared electrodes are investigated in-situ in our fuel cell test system. Polarization plots (in-situ cell performance) using these MEAs have been tested under different operational conditions.

Femtosecond laser-induced nano structuring offers a novel approach to enhance the performance of porous transport layers (PTLs) in anion-exchange membrane water electrolysis. By applying ultrashort laser pulses to nickel felts, distinct surface morphologies were generated, including high-spatial-frequency laser-induced periodic surface structures (HSFL-LIPSS), irregular ablated surfaces, and hybrid structures. Surface area analysis revealed increases of up to 4-fold for LIPSS, 6-fold for hybrid structures (LIPSS+Ablation), and 9-fold for ablated surfaces compared to untreated fibers. Electrochemical testing showed reduced overpotentials for laser-treated samples, comparable to state-of-the-art electrodes despite the absence of catalyst layers. Overpotentials could be reduced by up to 6.5 % at 10 mA cm−2 and by up to 9.6 % at 100 mA cm−2 compared to the unprocessed felt. Notably, ablated structures, with the highest surface areas, exhibited microcavities that may entrap oxygen bubbles, limiting active site and reaction rates. The LIPSS structures demonstrated the lowest activation losses and highest current density (1.32 A cm⁻² at 2.0 V) due to their periodic morphology and enhanced electrolyte flow, representing a 17 % improvement at 2.0 V compared to the untreated felts. Moreover, Tafel slopes down to 66 mV dec−1 denote a performant kinetic while oxidation charge measurements revealed pronounced peaks for laser-treated samples, with ablated surfaces achieving the highest charge of 16.76 ± 1.64 C cm⁻². Chronopotentiometry revealed the LIPSS structures showing the highest resistance to degradation among the structured samples. These findings suggest femtosecond laser nano structuring as a promising method to improve PTL performance. Further application of catalyst layers could amplify the electrochemical efficiency of these advanced materials.

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.

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.

In this experimental work polymer electrolyte membrane fuel cell (PEMFC) electrodes are analysed, which are prepared by the use of two sorts of carbon nano fibres (CNF) serving as support material for platinum nano particles. Those CNFs, which are heat treated subsequently to their production, have a higher graphitisation degree than fibres as produced. The improved graphitisation degree leads to higher electrical conductivity, which is favourably for the use in PEMFC electrodes. Samples have been analysed, in order to determine graphitisation degree, electrical conductivity, as well as morphology and loading of the prepared electro catalyst. Membrane electrode assemblies manufactured from prepared electrodes are analysed in-situ in a PEM fuel cell test environment. It has been determined that power output for samples containing CNFs with higher graphitisation degree is increased by about 13.5%.