Catalytic Resonance Theory: Forced Dynamic Promotion of (Electro)Catalytic Reactions

Abstract

Catalysis is central to our way of life and will play a pivotal role in the transition to clean energy and carbon-neutral manufacturing. While the current industrial processes used to synthesize chemicals from fossil-fuel derived feedstocks are highly optimized, development of higher-performance catalysts is needed for new, carbon-free processes based on renewable electricity and feedstocks to reach cost parity with current methods. Catalyst design is, however, far from trivial. One catalytic material must balance numerous elementary steps occurring on the same active site, each with unique energetic requirements, and the binding energies of these reaction intermediates are usually correlated, meaning a catalyst cannot independently stabilize a single species without impacting the other reaction intermediates in a similar manner. These limitations give rise to the Sabatier principle, which stipulates that the optimal catalyst for a reaction must bind molecules with intermediate strength. Too weak, and adsorption or reactant activation is insufficient; too strong, and product desorption is inhibited. This leads to a framework through which catalyst design has been rationalized, with significant research efforts devoted to overcoming the Sabatier limit by breaking the associated energy scaling relations. However, no significant advances have been reported in recent decades. In this dissertation, we discuss an alternative strategy for enhancing catalyst performance. Instead of optimizing a single site to balance the various elementary steps of a reaction, we propose designing catalysts with dynamic (tunable) active sites that can be optimized at the timescale of a catalytic turnover. This dynamic (“programmable”) catalyst is no longer constrained by the Sabatier principle because the active site can be tuned to accommodate the energetics of all kinetically relevant elementary steps during reaction, and can, in theory, surpass the Sabatier limit. Herein, we use microkinetic modeling to investigate the unique capabilities of dynamic catalysts, including accelerating rates beyond the Sabatier limit, achieving supra-equilibrium conversion, imparting net directionality into a closed reaction loop, and decreasing the overpotential of the electrocatalytic oxygen evolution reaction. The robustness of the predictions of these models are interrogated using a Monte Carlo-based uncertainty and variance-based global sensitivity analysis, which account for error in the parameterization of these dynamic catalysts. Finally, we propose a method for fabricating programmable catalysts based on parallel plate capacitors (“catalytic condensers”), and through a combination of experimental and computational investigations, demonstrate that catalytic condensers can tune the reactivity of both alumina and platinum thin film catalysts supported on graphene.