Principles of Dynamic Heterogeneous Catalysis: Surface Resonance and Turnover Frequency Response

Abstract

Acceleration of catalytic transformation of molecules via heterogeneous materials occurs through design of active binding sites to optimally balance the requirements of all steps in a catalytic cycle. In accordance with

Catalytic resonance theory: parallel reaction pathway control

“…11,12 An alternative strategy for catalytic reaction control proposes a dynamic catalytic surface, whereby the binding energy (i.e., heat of adsorption) of surface intermediates and associated transition state energies oscillate on the time scale of the catalytic turnover frequency. 13 The heat of adsorption of hydrocarbons on metals and metal oxides can be altered by several methods 14,15 including electric and magnetic elds, [16][17][18][19] photocatalysis, 20 surface strain, 21,22 solid electrolytes, [23][24][25][26][27] catalytic diodes, [28][29][30] and back-gated eld effect modulation. [31][32][33] For each combination of catalyst material, chemical mechanism, and method of external stimulus, the dynamic variables including imposed surface binding energy frequency f and amplitude DU comprise a narrow set of conditions which can potentially achieve catalytic turnover frequencies which are orders of magnitude above the static Sabatier maximum (i.e., Balandin-Sabatier volcano peak).…”

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

“…The ideal active site for product desorption is unlikely to also be ideal for surface reaction and reactant adsorption. However, a dynamic catalytic active site that changes on the time scale of the turnover frequency of the reaction could evolve over the catalytic cycle, providing an optimal energetic environment for each step and the overall progression of the reaction sequence (49) . A single active site can be modulated to alternate between ideal characteristics for product desorption, reactant adsorption, and surface reaction.…”

Shining light on the solid–liquid interface:in situ/operandomonitoring of surface catalysis

“…122 The application of modulation excitation methods, in which one or more reaction parameters (such as temperature, reactant composition, pressure or voltage) are switched between different states, will provide unique insight into the nature of reactive intermediates in solid-liquid catalysis. Such studies have proven valuable for gas-phase systems, 167 and furthermore recent modelling 168,169 and experiments 170 have demonstrated that careful tuning of the modulation frequency can result in catalytic resonance offering the tantalising possibility of overcoming the Sabatier principle for static reactions, thereby unlocking rate enhancements of 10-10 000× for reactions such as formic acid electrooxidation. Inducing rapid switching of temperature, pressure and concentration will prove difficult for conventional liquid phase reactors, due to slow heat/mass transfer compared to gas phase catalysis, however the use of microfluidic reactors, and light or electrical 170 excitation for catalytic stateswitching are promising solutions.…”