(187f) Microkinetic Modeling of Carbon Dioxide Electroreduction at Single Metal Atom Catalysts

Increasing CO₂ concentration into the atmosphere has resulted in extensive climate change. Capturing and converting CO₂ into useful chemicals such as alcohols and alkanes is one strategy to address this problem. Atomically dispersed, carbon based single metal atom catalysts have been shown to reduce CO₂ with Faradaic efficiency over 50% at low overpotentials.¹ However, the mechanism of CO₂ eletroreduction at single metal atom catalysts is poorly understood, and further mechanistic understanding will support the optimization of surface chemistry that controls catalytic performance.

In this work, single metal active sites were simulated using first-principle based Density Functional Theory (DFT) to calculate activation energy barriers of the CO₂ reduction reaction and accompanying hydrogen evolution. Marcus theory was implemented to describe the potential dependence of activation energy.² Finally, kinetic parameters obtained from DFT calculations and experiments were incorporated into a microkinetic model, and product evolution was determined as a function of electrode polarization. Binding energies of the adsorbed species, and their impact on surface coverage, plays an important role in CO selectivity.

References:

1. T. Asset et al., ACS Catal., 9, 7668–7678 (2019).
2. S. A. Akhade, N. J. Bernstein, M. R. Esopi, M. J. Regula, and M. J. Janik, Catal. Today, 288, 63–73 (2017).