Programmable chemical sensitivities scale with extent of reaction, not time

The programmable oscillation of external energetic stimuli to drive a catalytic surface between distinct regimes of kinetic control has emerged as a strategy to surpass steady-state Sabatier limitations, yet experimental probes of the underlying kinetic origins of rate enhancement remain limited. Here, we demonstrate that chemical sensitivities such as apparent reaction orders, activation energies, and the Gibbs free energy, scale with reaction events (extent of reaction) under oscillatory conditions and not time. Using formic acid electro-oxidation on polycrystalline Pt as a model system, an analytical framework demonstrating that transient kinetic parameters are governed by reaction event weighting was developed, rather than time-weighted averages based on duty cycle. Experimentally observable charge transfer during potentiodynamic oscillations provided a direct and quantitative measure for the extent of reaction, enabling prediction of dynamic chemical sensitivities across a wide range of oscillation timescales (10 -3 - 10 1 Hz) and reaction conditions (285-305 K, 0.05-2.5 M HCOOH). The extent of reaction formalism accurately reconciled experimentally observed potentiodynamic reaction orders and activation barriers with steady-state behavior. Although developed for electrochemical potential oscillations, the extent of reaction weighting framework is universal and readily applicable to any catalytic system driven by programmable energetic stimuli (e.g. electrical, photonic, mechanical).