TY - THES ID - 135299762 TI - Development of a scalable, sunlight-driven and water vapour-fed electrolyzer for hydrogen production AU - Denis, Paulien AU - Martens, Johan. AU - Rongé, Jan AU - KU Leuven. Faculteit Bio-ingenieurswetenschappen. Opleiding Master in de bio-ingenieurswetenschappen. Milieutechnologie (Leuven) PY - 2018 PB - Leuven KU Leuven. Faculteit Bio-ingenieurswetenschappen DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:135299762 AB - In the future, hydrogen will be able to play an important role as a transportation fuel and storage medium for renewable sources. Current hydrogen production is still dominated by steam reforming of fossil fuels, but the share of more sustainable alternatives such as alkaline and proton exchange membrane (PEM) electrolysis is growing. However, these systems pose different issues, of which the high capital costs and high prices of the required noble metal catalysts are most prominent. A vapour-fed solar hydrogen generator implementing an anion exchange membrane was investigated as an interesting and cost-saving alternative. The objective of the thesis was to develop an electrolyzer, integrating different alternatives for three components: the electrolyzer frame, the current collector and the membrane electrode assembly (MEA). It was aimed to operate using water vapour from ambient air and solar energy captured by a solar panel as only resources. An electrolyzer frame was designed and 3D printed in a polymer material, VeroWhitePlus. Various alternatives were evaluated as current collectors of which the most promising configuration, with a negligible Ohmic resistance, was a combination of nickel foil as current collector and nickel foam as gas diffusion layer (GDL). The most essential component influencing electrolyzer performance is the MEA. A KOH-impregnated PVA membrane was used in all MEAs. Ionomer spraying, electrodeposition of NiFe (anode) and NiMo (cathode) on the Ni foam GDL and the catalyst coated membrane (CCM) method were evaluated as methods to increase activity and stability of the MEA. Spraying of the Ni foam with ionomer did not show any significant benefits. The only long term stable CCM, sprayed with a Ni nanoparticle and PVA ionomer ink (ratio 2:1), attained a current density of 10 mA/cm² at 2.59 V. The most promising combination was a MEA with the membrane sandwiched between two Ni foams electrodeposited with NiFe and NiMo and sprayed with FAA ionomer, with an active surface of 4 cm². Stable current densities of 10 mA/cm² were attained at a potential of 1.82 V. This MEA was scaled-up to an active surface of 25 cm² and tested with ambient air as water vapour supply. The electrolyzer was coupled to a solar panel with a DC/DC converter providing a constant potential of 1.808 V. The experiment proved successful, attaining current densities of 4 mA/cm² and an estimated solar-to-hydrogen efficiency of 1.38%. Further research is needed to investigate long term stability and to optimize all integrated components of the electrolyzer. ER -