On the promotion of catalytic reactions by surface acoustic waves
Surface 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...
| Autores: | , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:ddd.uab.cat:238791 |
| Acceso en línea: | https://ddd.uab.cat/record/238791 https://dx.doi.org/urn:doi:10.1002/anie.202005883 |
| Access Level: | acceso abierto |
| Palabra clave: | Heterogeneous catalysis LEEM PEEM Surface acoustic waves Work function |
| Sumario: | Surface 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. Surface acoustic waves (SAWs) are dynamic lattice distortions, which can be excited on piezoelectric materials. For many years a promotion of the catalytic activity and selectivity by SAWs has been known, but no mechanistic understanding has been established yet. We quantify the effect that SAWs have on the electronic and geometric structure of a model catalyst, providing a basis for discussing the promotion mechanism of SAWs in catalytic surface reactions. |
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