Photoelectrochemical Hydrogen Isotope Separation on Advanced Semiconductor-Electrocatalyst Systems

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One of the greatest challenges of modern isotope separation technologies is to separate isotope mixtures at high purity, low costs and minimal energy input. The efficient separation of deuterium (2H2 or D2) and tritium (3H2 or T2) which are irreplaceable for various industrial and scientific applications creates an immense economic value. Current separation methods suffer from low separation efficiencies owing to the similar chemical properties of hydrogen isotopes and multiple, energy and cost-intensive separation steps. Electrolysis is one of the most effective processes for hydrogen isotope separation since the H/D and H/T separation factors (S) are determined by the hydrogen evolution reaction (HER) kinetics at the electrode surface. Presently, highly efficient semiconductor-electrocatalyst systems are developed for the photoelectrochemical generation of hydrogen as a so-called 'solar fuel' which have yielded the hitherto highest solar-to-chemical conversion efficiencies and stabilities when combining surface modified photovoltaic tandem absorbers with high activity electrocatalysts. In this project, we investigate these photoelectrode systems for photoelectrochemical hydrogen isotope separation in order to achieve two main goals. We aim at using the different electrochemical properties of isotopic aqueous electrolyte solutions to advance the understanding of HER kinetics at the electrode-electrolyte interface to draw mechanistic conclusions on the dependence of HER on temperature, pH, electrolyte composition and applied potential (i) and secondly, to lay the scientific foundations for the development of an efficient technologically relevant process for photoelectrochemical hydrogen isotope separation utilising solar energy as the main energy source (ii).