NSF-DFG Echem: Elucidating Surface Structure Contribution of Facets, Steps and Kinks in Electrocatalysis of the Oxygen Evolution and Reduction Reactions

该项目是科罗拉多矿业学院(美国)、美国国家可再生能源实验室(美国)、德国奥尔登堡卡尔·冯·奥西耶茨基大学(德国)和德国航空航天中心(DLR)之间的国际合作项目。电解是利用可再生能源生产绿色氢气的关键技术，而燃料电池是将储存的能量转化为电能的关键。这两种技术都需要催化剂，而这些催化剂目前正与缓慢的动力学作斗争，限制了它们的效率，因此需要开发改进的电催化剂。目前，电解水器和燃料电池使用的金属稀缺而昂贵，从而限制了大规模商业化。在这项研究计划中，我们的目标是通过基础研究和表面操作，使用富含稀土的材料，如第一排过渡金属(镍、铁、钴、锰或铜)，以金属氧化物的形式作为电催化剂。该项目汇集了美国和德国的科学家和工程师，致力于这一具有挑战性的项目，从而为参与其中的学生提供独特的教育体验。该项目的总体目标是为放氧反应(OER)和氧气还原反应(ORR)创造更高性能、更持久的非贵金属催化剂。由阴离子交换膜(AEM)的化学性质建立的碱性条件使得可以使用替代催化材料来实现AEM水电解(AEMWE)中的OER和AEM燃料电池(AEMFC)中的ORR。岩盐结构可以合成具有(111)或(100)表面的形状可控的金属氧化物颗粒，这是其他晶体结构(如尖晶石或钙钛矿)所不能(容易)实现的，从而可以阐明它们在氧电催化中的作用。此外，这些材料提供了理想的平台来系统地研究用台阶和扭结来裁剪表面以及用类似离子半径的元素(如Co、Mn、Fe)制造多金属氧化物的效果。我们的中心假设是，控制催化剂的表面终止和小面暴露可以改变表面的配位和成键环境，从而改变反应物-催化剂的相互作用和电催化OER/ORR活性。因此，合成、表面形态和电化学性能之间的联系将提供对催化剂设计至关重要的潜在基础知识。这项研究是在NSF-DFG领导机构电合成和电催化活动机会NSF 20-578下资助的。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project is an international collaboration between the Colorado School of Mines (USA), the National Renewable Energy Laboratory (USA), Carl von Ossietzky University Oldenburg (Germany) and the German Aerospace Center-Deutsches Zentrum für Luft- und Raumfahrt (DLR) in Germany. Electrolysis is a key technology to generate green hydrogen using renewable energies while fuel cells are crucial for converting stored energy into electrical energy. Both technologies require catalysts which currently struggle with sluggish kinetics limiting their efficiencies and thus requiring the development of improved electrocatalysts. Currently, water electrolyzers and fuel cells use metals that are scarce and expensive thereby limiting large-scale commercialization. In this research program we target the use of earth abundant materials such as first row transition metals (Ni, Fe, Co, Mn or Cu) in the form of metal oxides as electrocatalysts through fundamental study and manipulation of the surfaces. This project brings together American and German scientists and engineers to work on this challenging project thus providing a unique educational experience for the students involved.The overarching goal of this project is to create higher performing, more durable non-precious metal catalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Alkaline conditions established by the chemical nature of an anion exchange membrane (AEM) enable the usage of alternative catalytic materials for the OER in AEM water electrolysis (AEMWE) and ORR in AEM fuel cells (AEMFC). The rock salt structure enables synthesis of shape-controlled metal oxide particles with (111) or (100) surfaces, which are not (easily) achievable for other crystal structures like spinels or pervoskites, allowing elucidation of their role in oxygen electrocatalysis. Further, these materials offer ideal platforms to systematically study the effects of tailoring the surfaces with steps and kinks and making multi-metal oxides with elements of similar ionic radii (e.g. Co, Mn, Fe). Our central hypothesis is that controlling the surface termination and facet exposure of a catalyst can alter the coordination and bonding environments at the surface thus changing the reactant-catalyst interaction and the electrocatalytic OER/ORR activity. Therefore, the connection between synthesis, surface morphology and electrochemical performance will provide the underlying fundamental knowledge crucial for the design of catalysts.This research was funded under the NSF-DFG Lead Agency Activity in Electrosynthesis and Electrocatalysis (NSF-DFG EChem) opportunity NSF 20-578.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.