Electrocatalysts and polymer thin films for solar-driven vapour phase water splitting. An investigation by electrochemical impedance and nuclear magnetic resonance spectroscopy

A zero carbon society will require not only renewable electricity, but also renewable fuels. One of the attractive options are devices that mimick natural photosynthesis and produce hydrogen from water using solar energy. Even more elegant is a recently developed type of device which uses ambient air as the source of water. This could be installed anywhere, since only sunlight and air are needed. The production of hydrogen from water involves water splitting reactions (water oxidation and hydrogen evolution) that require a certain electrical potential to occur. The efficiency of solar energy conversion can be enhanced by minimizing the required potential. This can be done by incorporating catalysts which facilitate these reactions. The best known catalysts, noble metals, are rare and expensive. Therefore alternatives are being developed based on low cost elements that are abundant in the Earth's crust. Those elements are the same ones found in the enzymes of plants that carry out the same reactions. However, they have only been tested in liquid solutions. In this project those low cost materials will be investigated in vapour phase, covered by a thin polymer material. This will be done by electrochemical measurements and by more advanced methods to give insight in their molecular structure and dynamics during the reaction. If a suitable catalyst can be found which is active and stable, it can be used in an airbased solar hydrogen device.