Electrocatalytic activity and dissolution stability of high entropy alloys at the atomic scale

ended

The Covid-19 pandemic and the international conflicts are now having a significant impact on energy systems around the world, potentially slowing the expansion of clean energy applications. European energy safety can only be ensured by accelerating the development of cheap and clean energy. Catalysts for the chemical reactions in energy conversion and storage, such as fuel cells and water-splitting, are critical to achieve large-scale clean energy production. However, the scarcity of noble metals (such as Pt, Ir), currently the state-of-the-art catalysts, limit their apllications. Co, Fe and Ni oxides are proved to be earth abundant alternative catalysts. Corrosion of these transition metal-based electrocatalysts is inevitable, particularly for the oxygen evolution reaction of water splitting. Transition metal-based high entropy alloys (HEAs), the homogeneous “mixtures” at the atomic level of at least 5 transition metals, exhibit high electrocatalytic activity compared to binary oxides and also high corrosion resistance compared to stainless steels. These unusual properties of HEAs arise from atomically ordered but elementally disordered structures, which are poorly understood. I will explore, for the first time, the surface disorder of HEAs at the atomic scale, by synthesizing nanofilms of 5-element alloys in ultra-high vacuum (UHV) and using advanced surface analytical techniques (mainly STM, XPS). I will perform electrochemical measurements on synthesized model HEAs’ surfaces in a home-made movable reaction cell that can be connected to different UHV systems, in order to correlate atomic-scale structures with catalytic and anti-corrosion properties. I will merge my previous expertise in STM, XPS techniques and surface reactivity of ternary alloys into the host’s experience in thin film alloy synthesis and catalysis. The overall objective of this project is to find the balance between the activity and the stability of HEAs for water splitting electrocatalysis.