MONOLAYER CATALYST AS TRANSFORMATIVE CONCEPT FOR EFFICIENT ELECTROLYTIC HYDROGEN ISOTOPE SEPARATION

brankovic, Stanko r . .研究了铂（Pt）和钯（Pd）单层催化剂中正应变对电解氢同位素分离效率的影响，如从正常水中分离重氘水（D2O）。提高分离效率将有助于为目前的裂变型核反应堆生产更便宜的慢化剂材料，并为未来的聚变反应堆提供关键的燃料组件。这些技术将有助于为我国实现一个安全的能源未来，同时促进安全的核能实施和扩散。更广泛地说，为氢同位素分离开发的技术也可以应用于许多其他的电解同位素分离。这个想法是建立在金属单层薄膜的前提下，由外延与衬底失配引起的正应变增加了过电位区域中吸附氢键的强度，在过电位区域中氢原子的重组是析氢反应的速率决定步骤。因此，与体Pt和Pd电极相比，单层Pt和Pd的氢同位素分离效率有望提高。正应变也增加了吸附氢原子的表面扩散屏障。这种效应有利于质量较小的同位素的重组。随着表面的拉伸，相邻的吸附位点相互分离，这对重氢同位素的影响更大，导致它们的重组概率更低，从而提高了分离效率。为了研究Pt和Pd单层催化剂中的应变效应，我们提出利用电化学沉积和表面限制氧化还原取代反应沉积在Au（111）上合成连续Pt和Pd单层催化剂。采用红外光谱法研究氢同位素的吸附强度。这些结果将用作我们的DFT计算和理论分析的起始输入。计算得到的Pt和Pd单层及相应体电极的氢氘复合速率与分离因子之比将与实验测量值进行比较。如有需要，我们会根据输入参数、近似值和考虑的影响，进一步完善理论模型/计算。这一迭代过程将有助于充分理解和量化分离应变对Pt和Pd单层分离效率的影响。此外，该项目将为研究生提供一个高度跨学科的学习环境，涉及电化学，材料科学和催化的要素，这些都对我国的技术领先至关重要。

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.