(6e) Microkinetic Modeling Guided CO Electroreduction to Acetate in Multiphase System

Acetate, a key chemical reagent across many industries, is produced through methods like bacterial fermentation, chemical synthesis, and, notably, electrocatalysis. Derived from the reduction of carbon dioxide, carbon monoxide serves as an effective feedstock for electrochemical reduction processes in liquid/gas/solid triple phase with lower energy use and reduced greenhouse gas emissions, operating under moderate conditions and showing a high selectivity for C2+ products. The transformation from CO to acetate, involving six proton-electron transfers, competes with the production of methane, ethanol, and ethylene. Factors such as solvation, cations, applied potential, pH, and CO pressure affect the activity and selectivity towards acetate. However, the current experimental approach relies on trial and error, limited by a lack in understanding the reaction kinetics, critical intermediates, rate/selectivity determining steps under operational conditions.

In response to these challenges, this study presents a detailed microkinetic model (MKM) that integrates the reaction pathways from CO to a range of potential products on Cu(100), informed by grand-canonical density function theory (GC-DFT) calculations with simulating the reaction energetics and barriers under constant potentials under explicit solvation and cation effects for electrochemical systems.¹ The GC-DFT results further incorporate into transition state theory to calculate the equilibrium constants and reaction rate constants for each proposed elementary step within CORR. Consequently, a detailed MKM is established, which shows the key intermediates, reaction kinetics and selectivity of CORR to different products under a range of potentials, pH, temperature, and CO partial pressure. Through sensitive analysis, the model identifies the potential rate-limiting step and selectivity determining step for acetate formation. Our MKM can provide the design rules for enhancing the energy efficiency, activity, and selectivity of acetate synthesis via CORR electrocatalysis.

References

(1) Xu, Y.; Che, F. Microkinetic Modeling Guided CO Electroreduction to Acetate in Multiphase System. In Preparation 2024.