How surface acoustic waves can enhance catalytic activity

An international team of researchers have studied the mechanism by which surface acoustic waves (SAW) enhance catalytic activity. They were able for the first time to measure the effect of SAW on the electronic structure of a Pt model catalyst and achieved a remarkable precision with the new experimental setup at the CIRCE beamline in the ALBA Synchrotron.

The enhancement of catalytic activity (i.e. how certain materials help interesting chemical reactions to take place easier, faster, more directed or under more desirable conditions like lower temperature) by surface acoustic waves (SAW) is an established phenomenon, but its mechanism is still not well understood. Previous experiments showed that the electronic work function of model catalyst (e.g. Platinum, Pt) change within seconds to minutes when SAW are applied. This work function change was thought responsible for the SAW induced catalytic enhancement.

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Image: Figure: Work function oscillation in a thin Pt film imaged by stroboscopic X-ray photoemission electron microscopy (XPEEM). It is caused by the elastic deformation of the surface region by a Surface Acoustic Wave (SAW) in an underlying LiNbO3 substrate, The strong oscillation in the lower area is in the bare substrate and shows a large piezoelectric ampltiude. The periodicity serves as reference for the much smaller effect in the metallic Pt film. In the inset, a line profile extracted from the white box in the upper part of the image, indicates a work function oscillation of 455 µeV amplitude in Pt.