The quantum mechanics derived atomistic mechanism underlying the acceleration of catalytic CO oxidation on Pt(110) by surface acoustic waves

Abstract

Experimental evidence that surface acoustic waves (SAW) can significantly enhance the rate of catalytic oxidation of CO to CO 2 over the Pt(110) catalyst surface [S. Kelling et al. Faraday Disc. 1997, 107, 435−444] is examined using quantum mechanics (QM) simulations. First we determined the QM based mechanism for the O 2 -rich régime of the reaction, and the energy landscape of CO interacting with an O-covered reconstructed Pt(110) surface at both static and dynamic levels, but in the absence of SAW. We then utilized ab initio molecular dynamic (AIMD) simulations to determine how SAW might modify the kinetics. We focus here on the short (picosecond time scale) shock spikes induced by switching of domains in the piezoelectric driver on which the catalyst is deposited. We find that SAW-induced spikes promote dynamic changes in the diffusion and desorption, from which we estimate the influence of SAW on CO oxidation rate over Pt(110). We find good agreement with the experimentally observed catalytic enhancement by SAW. With an atomistic mechanism in place one can now consider how to use SAW to enhance other catalytic reactions.

The Catalytic Mechanics of Dynamic Surfaces: Stimulating Methods for Promoting Catalytic Resonance

“…Surface acoustic waves have been observed using a Doppler imaging method with an oscillation amplitude of several nanometers up to 200 nm normal to the surface. ,, These dynamic deformations when propagating through films of Cu, Au, and Pd metal were observed by photoelectron emission microscopy to shift the work function of these catalytic surfaces . The resulting deformation-derived electronic tuning of the material has been attributed to several unique catalytic behaviors including increased rates of CO oxidation on Pt , and ethanol oxidation to acetaldehyde on Pd . While the precise mechanism(s) leading to variation in binding energy and catalytic turnover remain under discussion, definitive evidence exists of significant physical and electronic catalyst changes in the presence of Rayleigh surface acoustic waves.…”

On the Promotion of Catalytic Reactions by Surface Acoustic Waves

“…Experimentally, a smaller enhancement of the surface diffusion coefficient of Au clusters on a Si(111) surface by a factor of 19 was found [13] . Similarly, in a MD simulation the non‐linear properties of SAWs were made responsible for the promotion of catalytic CO oxidation on a (110) oriented Pt surface [14] . The promotion effect was attributed to shock spikes caused by SAWs, which would enhance the diffusion and desorption of adsorbed CO molecules.…”

“…[13] Similarly,i naM D simulation the non-linear properties of SAWs were made responsible for the promotion of catalytic CO oxidation on a( 110) oriented Pt surface. [14] Thep romotion effect was attributed to shock spikes caused by SAWs,w hich would enhance the diffusion and desorption of adsorbed CO molecules. None of the above cited explanations can explain the time scale with which the reaction rate responds to SAWs.…”

Platinum Graphene Catalytic Condenser for Millisecond Programmable Metal Surfaces

“…Our results above demonstrate that the Pt/graphene catalytic condenser can statically shift the electronic properties of Pt active sites, but the next opportunity for applying this technology is the dynamic oscillation of active sites to accelerate and control catalytic reactions. (70,71) We have recently outlined a strategy for achieving significantly faster catalytic turnover frequencies, even beyond the Sabatier limit, by oscillating the energetic properties of catalyst sites. (72,73,74) Using the descriptor of the surface binding energy of a reaction intermediate, rate acceleration becomes substantial at an active site that is oscillating the binding energy of the selected intermediate in excess of ~0.2 eV (19.3 kJ mol -1 ).…”