Photoelectrochemical Hydrogen Isotope Separation on Advanced Semiconductor-Electrocatalyst Systems

现代同位素分离技术的最大挑战之一是以高纯度、低成本和最小的能量投入分离同位素混合物。氢(2H2或D2)和氚(3H2或T2)的有效分离在各种工业和科学应用中是不可替代的，创造了巨大的经济价值。目前的分离方法由于氢同位素的化学性质相似，以及多个耗能和成本高的分离步骤，导致分离效率低下。电解是氢同位素分离最有效的过程之一，因为H/D和H/T分离因子(S)是由电极表面的析氢反应动力学决定的。目前，高效的半导体-电催化体系被开发用于光电化学产生氢气，作为一种所谓的太阳能燃料，将表面修饰的光伏串联吸收体与高活性电催化剂相结合，产生了迄今为止最高的太阳能-化学转换效率和稳定性。在本项目中，我们研究了这些用于光电化学氢同位素分离的光电极系统，以实现两个主要目标。我们的目的是利用同位素水溶液的不同电化学性质来加深对电极-电解液界面上的HER动力学的理解，从而得出HER与温度、pH、电解液组成和外加电位(I)之间的依赖关系的机理结论，其次，为开发一种高效的以太阳能为主要能源的光电化学氢同位素分离工艺奠定科学基础(II)。

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).