TY - JOUR

T1 - On the Promotion of Catalytic Reactions by Surface Acoustic Waves

AU - von Boehn, Bernhard

AU - Foerster, Michael

AU - von Boehn, Moritz

AU - Prat, Jordi

AU - Macià, Ferran

AU - Casals, Blai

AU - Khaliq, Muhammad Waqas

AU - Hernández-Mínguez, Alberto

AU - Aballe, Lucia

AU - Imbihl, Ronald

N1 - Funding Information: The authors thank Werner Seidel for technical support in the fabrication of the IDTs, Rolf J. Haug, Hannover, for help in preparation of the samples, and Leo Zhigilei for carefully reading the manuscript. The research leading to this result has been supported by the project CALIPSOplus under Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. LA and MF acknowledge support from Spanish MINECO through Grant No. RTI2018‐095303‐B‐C53. FM and BC acknowledges support from Spanish MINECO through Grants No. RYC‐2014‐16515, No. MAT2015‐69144‐P, No. SEV‐2015‐0496 and No. MAT2017‐85232‐R. Open access funding enabled and organized by Projekt DEAL.

PY - 2020/10/26

Y1 - 2020/10/26

N2 - 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.

AB - 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.

KW - heterogeneous catalysis

KW - LEEM

KW - PEEM

KW - Surface acoustic waves

KW - work function

UR - http://www.scopus.com/inward/record.url?scp=85089899993&partnerID=8YFLogxK

U2 - 10.1002/anie.202005883

DO - 10.1002/anie.202005883

M3 - Article

C2 - 32729648

AN - SCOPUS:85089899993

VL - 59

SP - 20224

EP - 20229

JO - Angewandte Chemie

JF - Angewandte Chemie

SN - 1433-7851

IS - 45

ER -