Catalytic resonance theory: Negative dynamic surfaces for programmable catalysts

Abstract

Catalysts that change with time via programmed variation of their electronic occupation to accelerate surface reactions were evaluated in the case of negative adsorption energy scaling relations. Defined as the relative change in adsorption enthalpy, the gamma linear scaling parameter is negative when two adsorbates alternatively weaken and strengthen as catalysts are electronically perturbed. Simulations were conducted of a single transition state connecting two generic adsorbates representative of multiple reaction classes to understand the resulting negative gamma catalytic ratchet mechanism and its ability to accelerate catalytic reactions above the Sabatier peak and away from equilibrium. Relative to conventional positive gamma catalytic ratchets, the Sabatier volcanoes of negative gamma catalysis are narrower with greater enhancement of dynamic turnover frequency when catalysts are electronically oscillated. Promotion of the catalytic surface reaction forward or backward was predictable by a descriptor accounting for the relative rates of forward and reverse kinetics under oscillatory conditions. • Identified the most energy efficient negative dynamic reaction energy profile • Optimized negative scaling dynamic catalysts using their tunable design parameters • Developed a global descriptor to predict reaction selectivity at high conversion The emergence of low-cost solar and wind power requires new catalytic technologies that can achieve faster rates for hydrogen production and ammonia synthesis as a method for storing and moving renewable energy. These two important catalytic reactions are limited by the Sabatier principle, making them too slow by conventional static catalysis for small-scale implementation nearby distributed power sources. However, the application of dynamic programmable catalysts for these chemistries can accelerate the catalytic turnover frequency substantially above the Sabatier limitation. In particular, negative scaling relationships have been predicted for the synthesis of energy-dense liquids, and these negative gamma programmable catalysts achieve high efficiency in both rate acceleration and reaction promotion relative to energy input, making them ideal catalytic devices for energy intensive catalytic chemistry. The promotion of reactions using surfaces that change with time can be achieved with programmable surfaces that feature negative scaling relationships between the reactant and the product. These programmable surfaces exhibit unique catalytic behavior to accelerate reactions and push the extent of conversion away from equilibrium.