CC BY-NC 4.0 Unportedvon Boehn, BernhardFoerster, Michaelvon Boehn, MoritzPrat, JordiMacià, FerranCasals, BlaiKhaliq, Muhammad WaqasHernández-Mínguez, AlbertoAballe, LuciaImbihl, Ronald2021-09-172021-09-172020https://oa.tib.eu/renate/handle/123456789/6841https://doi.org/10.34657/5888Surface acoustic waves (SAW) allow to manipulate surfaces with potential applications in catalysis, sensor and nanotechnology. SAWs were shown to cause a strong increase in catalytic activity and selectivity in many oxidation and decomposition reactions on metallic and oxidic catalysts. However, the promotion mechanism has not been unambiguously identified. Using stroboscopic X-ray photoelectron spectro-microscopy, we were able to evidence a sub-nanosecond work function change during propagation of 500 MHz SAWs on a 9 nm thick platinum film. We quantify the work function change to 455 μeV. Such a small variation rules out that electronic effects due to elastic deformation (strain) play a major role in the SAW-induced promotion of catalysis. In a second set of experiments, SAW-induced intermixing of a five monolayers thick Rh film on top of polycrystalline platinum was demonstrated to be due to enhanced thermal diffusion caused by an increase of the surface temperature by about 75 K when SAWs were excited. Reversible surface structural changes are suggested to be a major cause for catalytic promotion. © 2020 The Authors. Published by Wiley-VCH GmbHenghttps://creativecommons.org/licenses/by-nc/4.0/540heterogeneous catalysisLEEMPEEMSurface acoustic waveswork functionArticle