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Project grant
Title [sv]
Mot bättre förståelse av ytegenskaper under fotokatalytisk sönderdelning av vatten
Title [en]
Towards Improved Understanding of Surface Properties during Photocatalytic Water Splitting
Abstract [en]
Photocatalytic water splitting is a process where the energy of the sunlight is utilized to separate water into molecular oxygen and hydrogen where the latter can be used as an energy carrier. Here, hydrogen from water is particularly interesting since it forms a carbon-free system and, if done effectively enough, could be an important part of a future post-petrochemical-energy systems. We have recently shown that one can obtain over 10% solar-to-hydrogen efficiency by constructing series-connected copper-selenium-based materials with separate materials optimized for the surface catalysis. This is a much cheaper option than tandem concepts and photons with wavelength up to 1200 nm in the solar spectrum can be utilized and give the charge carriers enough potential energy to decompose water with high efficiency. Although promising results have been achieved, the global effort to develop an effective and sustainable solar hydrogen production has now reached a stage where an improved understanding of the fundamental properties of the surface of the catalyst during operation is essential for further progress. In this context, it is crucial that new experimental methods are developed to study the chemical substances that are formed on the surface and the energy levels at the surface during the water splitting process for understanding and improving the plethora of proposed catalysts published during the last decades. In this project we will develop in-situ Raman spectroscopy combined with methods measuring the properties of the surface charges during the catalytic process. Preliminary measurements for bi-metallic alloys of cobalt and nickel show both the presence of Co-hydroxides as well as the dynamic formation and reformation of oxides during the catalysis under different applied potential. It is essential to also measure the populated energy levels and the work function of the catalyst materials to distinguish the oxide forming processes with the charge states that are not reflected in the formation of new species. This is one of the main tasks in this project and the project will start by utilizing our recently developed photoelectrochemical methods for determining absolute energy levels and trap states whereas a Kelvin Probe equipped with surface photovoltage capabilities will be used for measuring the work function of the catalysts. The developed methods and the separation of effects creating new species and the other charge states at the surface can also be important for many adjacent areas that also are dependent on critical processes in interface layers, as in photocatalytic water purification, sensor materials for detecting chemical substances in gas/solution, in battery electrode and electrolyte interfaces, and in some boundary layers in solar cells.
Principal InvestigatorEdvinsson, Tomas
Coordinating organisation
Uppsala University
2016-01-01 - 2019-12-31
National Category
Physical ChemistryMaterials ChemistryChemical Process Engineering
DiVA, id: project:5756Project, id: 2015-03814_VR