Understanding electrochemical switchability of perovskite-type exsolution catalysts

• DOI: 10.1038/s41467-020-18563-w
• Publication Date: 2020-09-23T10:03:33Z
• Authors: Alexander K. Opitz; Andreas Nenning; Vedran Vonk; Sergey Volkov; Florian Bertram; Harald Summerer; Sabine Schwarz; Andreas Steiger-T...; Johannes Bernardi; Andreas Stierle; Jürgen Fleig
• Keywords: Science; Q; 500; 01 natural sciences; 7. Clean energy; Article; info:eu-repo/classification/ddc/500; 0104 chemical sciences

AbstractExsolution of metal nanoparticles from perovskite-type oxides is a very promising approach to obtain catalysts with superior properties. One particularly interesting property of exsolution catalysts is the possibility of electrochemical switching between different activity states. In this work, synchrotron-based in-situ X-ray diffraction experiments on electrochemically polarized La0.6Sr0.4FeO3-δthin film electrodes are performed, in order to simultaneously obtain insights into the phase composition and the catalytic activity of the electrode surface. This shows that reversible electrochemical switching between a high and low activity state is accompanied by a phase change of exsolved particles between metallic α-­Fe and Fe-oxides. Reintegration of iron into the perovskite lattice is thus not required for obtaining a switchable catalyst, making this process especially interesting for intermediate temperature applications. These measurements also reveal how metallic particles on La0.6Sr0.4FeO3-δelectrodes affect the H2oxidation and H2O splitting mechanism and why the particle size plays a minor role.