Highly efficient porous electrodes of nanocrystalline metal-metalloid-powder coatings through short-time sintering

碱性电解水被认为是实现无碳能源循环的大规模制氢关键技术。为了提高这些设施的效率和经济性，需要对所有系统组件，特别是电极材料及其生产工艺进行持续的进一步发展。在这方面，高效电极需要良好的机械稳定性，良好定义的多孔样品表面以及高的固有电催化活性。后一种要求可以通过合适的化学成分和具有高密度表面缺陷的纳米晶状态来获得。特别是添加了Co、Mo、Si、B的非晶和纳米晶铁、镍基合金表现出优异的电催化活性。在这方面，短时间烧结技术，火花等离子烧结（SPS/FAST），可用于制造纳米晶金属半成品，节省时间和资源。此外，粗糙和多孔表面由于具有较高的活性表面积和优化的气泡管理而提高了电极的效率。在这个dfg项目中，计划将SPS/FAST技术用于具有多孔和纳米晶结构的薄层涂层，这些涂层粘合在金属基板上。这为根据要实现的应用实现高效的气体产生电极提供了机会。将合成由具有一定厚度和孔隙率的纳米晶金属-金属-粉末（MMP）组成的电催化活性涂层，该涂层将结合纳米晶材料和粗糙多孔表面结构的优点以及良好的机械稳定性。重点将是更好地理解mmp -涂层的短时烧结行为和结构性能的演变（晶粒尺寸、孔隙率、相形成和烧结颈的形成），这将通过烧结参数（压力、温度、加热速率和保温时间）的系统变化来研究。此外，还将评估涂层与基体之间界面的机械稳定性。在此基础上，研究了烧结mmp -涂层-基体-复合材料的电催化活性和长期稳定性与mmp -涂层结构性能的关系。从mmp -衬底复合材料的结构-性能关系中，我们将推导出高效和长期稳定的电极材料，用于可持续的水电解以及其他电化学制气过程。

The alkaline electrolysis of water is considered as a key technology for the hydrogen production at large-scale to fulfill a carbon-free energy circle. In order to enhance the efficiency and thereby the economy of such facilities, the consistent further development of all system components and, in particular, the electrode materials and their production processes are needed. In this regard, highly efficient electrodes require a good mechanical stability, a well-defined porous sample surface as well as a high intrinsic electrocatalytic activity. The latter requirement can be obtained by a suitable chemical composition and a nanocrystalline state which exhibits a high density of surface defects. Particularly, amorphous and nanocrystalline Fe- and Ni-base alloys with additives of Co, Mo, Si, B show excellent electrocatalytic activity. In this regard, the short-time sintering technology, spark plasma sintering (SPS/FAST), can be used to manufacture nanocrystalline metallic semi-finished products by saving time and resources. Furthermore, it is established that rough and porous surfaces improve the efficiency of the electrode due to a high active surface area and an optimized management of gas bubbles.In this DFG-project it is planned to utilize the SPS/FAST technology for thin layer coatings with a porous and nanocrystalline structure, which are bonded on a metallic substrate. This offers the opportunity to realize highly efficient, gas-generating electrodes in accordance with the application to be fulfilled. Electrocatalytic active coatings which consist of nanocrystalline metal-metalloid-powders (MMP) with a defined thickness and porosity will be synthesized, which shall combine the advantage of nanocrystalline materials and rough, porous surface structures together with a good mechanical stability. The focus will be the better understanding of the short-time sintering behavior and the evolution of the structural properties of the MMP-coating (grain size, porosity, phase formation and formation of sintering necks), which will be investigated by a systematic variation of the sintering parameters (pressure, temperature, heating rate and holding time). Furthermore, the mechanical stability of the interface between the coating and substrate will be evaluated. Based on this, the electrocatalytic activity as well as the long-term stability of the sintered MMP-coating-substrate-composite in dependence on the structural properties of the MMP-coating will be investigated. From the structural-properties relationship of the MMP-substrate composites valuable conclusions for highly efficient and long-term stable electrode materials for sustainable water electrolysis but also for other electrochemical processes of gas production will be deduced.