MONOLAYER CATALYST AS TRANSFORMATIVE CONCEPT FOR EFFICIENT ELECTROLYTIC HYDROGEN ISOTOPE SEPARATION

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1605331Brankovic, Stanko R.The study examines the effects of positive strain in platinum (Pt) and palladium (Pd) monolayer catalysts on the efficiency of electrolytic hydrogen isotope separation in applications such as separation of heavy, deuterated water (D2O) from normal H2O. Improved separation efficiencies would aid the production of cheaper moderator materials for current fission-type nuclear reactors and provide crucial fuel components for future fusion reactors. These technologies would help to achieve a secure energy future for our Nation while promoting safe nuclear energy implementation and proliferation. More broadly, the techniques developed for hydrogen isotope separation can also be applied to a host of other electrolytic isotope separations. The idea is built on the premise that positive strain in a metal monolayer-thin film, induced by epitaxial misfit with a substrate, increases the strength of the adsorbed hydrogen bond in the overpotential region where recombination of hydrogen atoms is the rate determining step in the hydrogen evolution reaction. As a result, an increased hydrogen isotope separation efficiency of Pt and Pd monolayers is expected as compared to bulk Pt and Pd electrodes. The positive strain also increases the surface diffusion barrier for adsorbed hydrogen atoms. This effect favors recombination of isotopes with smaller mass. As the surface is stretched, the neighboring adsorption sites separate from each other which affects heavier hydrogen isotopes more and results in their lower probability for recombination thus increasing separation efficiency. To study these strain effects in Pt and Pd monolayer catalysts we propose to synthesize continuous Pt and Pd monolayers on Au(111) using electrochemical deposition and deposition via a surface-limited redox replacement reaction pioneered by the principal investigator's group. The adsorption strength of hydrogen isotopes will be studied by infra-red spectroscopy. These results will be used as starting input in our DFT calculations and theoretical analysis. The calculated ratio between the rates of hydrogen and deuterium recombination and separation factors for Pt and Pd monolayers and corresponding bulk electrodes will be compared to experimentally measured ones. If necessary, additional sophistication of theoretical model/calculations in terms of the input parameters, approximations and considered effects will be implemented. This iterative procedure will help to gain full understanding and quantification of separate strain effects on separation efficiency of Pt and Pd monolayers. Furthermore, the project will provide a highly inter-disciplinary learning environment for graduate students involving elements of electrochemistry, materials science, and catalysis, all critically important for technological leadership of our country.