Non-precious bifunctional oxygen catalysts for regenerative seawater electrolyzers

不断增加的可再生太阳能和风能容量的不确定性推动了对越来越多合适的分子能量存储的需求。由电和水组成的氢被认为是最有前途的储能分子。今天，水分解是使用淡水进行的。更需要的是有效的电化学分解原始盐水。可逆海水电解槽，即将海水分解为氢气并将氢气转化为电力和淡水的组件，将使沙漠地区附近的海水能够实现自给自足的能源和淡水供应。为此，需要用于可逆氢电极和氧电极的新的合适的双功能电催化剂。这种催化剂尚未被探索。将在本项目框架内对此进行调查。总体目标是识别和分子理解的结构活性关系的新型非贵金属双功能催化剂的再生海水分裂可逆操作的膜基电解槽。为了实现这一目标，该项目将探索双组分催化剂系统的概念，作为在混合材料表面产生特殊活性位点的一种方式，其中每个组分将专门用于选择性海水裂解或将氢转化为电力和淡水。已有的结果表明，这种杂化材料表现出突出的双功能活性。然而，这种材料概念的分子机制和局限性仍然不清楚。为了解决这个问题，电化学活性和稳定性研究将与结构分析相结合，以开发可逆催化剂系统的结构，反应性和稳定性关系。将特别强调增强氯化物腐蚀和分子降解。新的基本材料的见解将在一个单电池可逆电解槽组件验证。由此，将产生关于碱性离聚物-催化剂-反应物三相边界及其稳定性的额外新知识。该项目针对结构，电荷传输，电催化稳定性和活性的广泛分析方法组合将提供基本的理解，但也将产生这种混合催化剂在更复杂的电解环境中如何表现的初步感觉。总之，该项目是对可再生能源储存材料科学的根本性贡献。

The intermittency of ever increasing renewable solar and wind energy capacities drives up demand for more and more suitable molecular energy storage. Hydrogen, made of electricity and water, is regarded the most promising energy storage molecule. Today, water splitting is carried out using fresh water. Much more desirable would be the efficient electrochemical splitting of raw saline sea water. Reversible seawater electrolyzers, i.e. assemblies that split seawater in hydrogen as well as convert the hydrogen in electricity and freshwater, will enable a self-sufficient energy and fresh water supply in seawater near desert regions. For that purpose new suitable bifunctional electrocatalysts for reversible hydrogen- and oxygen-electrodes are required. Such catalysts have not been explored yet. This will be investigated within the framework of this project. The overall goal is the identification and molecular understanding of structure activity relationships of novel non precious bifunctional catalyst for regenerative seawater splitting in reversibly operating membrane-based electrolyzers. To achieve this goal this project will explore the concept of two-component-catalyst systems as a way to generate special active sites at the surface of the hybrid material, where each component will be specialized to either the selective seawater splitting or the conversion of hydrogen in electricity and fresh water. Own prior results have shown that such hybrid materials exhibit outstanding bifunctional activity. Molecular mechanisms and limitations of this materials concept, however, are still unclear. To address this, electrochemical activity and stability investigations will be combined with structural analysis to develop structure-, reactivity- and stability-relationships for reversible catalyst systems. Special Emphasis will be put on enhanced chloride corrosion and molecular degradation. New fundamental materials insights will be verified in a single cell reversible electrolyzer assembly. Thereby, additional new knowledge about the alkaline ionomer-catalyst-reactant three-phase boundary and their stabilities will be generated. The broad analytical method portfolio of this project targeting structure, charge transport, electrocatalytic stability and activity will provide fundamental understanding, yet will also yield a first sense of how such hybrid catalyst perform in more complex electrolytic environments. In all this project is a fundamental contribution to the Materials Science of renewable energy storage.