Assessing pH and Voltage Effects on the Binding of CO to Model Copper Catalyst Surfaces Via a DFT-Continuum Theory

Abstract

The electrochemical conversion of CO2 to commodity products such as hydrocarbons and oxygenates is an attractive approach for generating non-fossil derived chemical and fuel stocks and for the storage of energy in chemical bonds. To date, a number of studies have shown that the activity and selectivity of copper-based catalysts for the CO2 reduction reaction towards valuable higher order carbon products are highly sensitive to the local reaction environment. Furthermore, the local electrolyte concentration and local pH is intimately tied to the applied voltage and the mass transport of reactants and products within the interfacial region. In recognition of this, several recent efforts focused on engineering the design of electrochemical reactors to reduce mass transport limitations indicate a pronounced effect on the apparent selectivity of the copper catalyst. While these efforts have highlighted a new direction for improving the efficiency of the CO2 reduction reaction, the rational design of these reactors remains challenging due to the need to optimize features of the reactor across multiple time and length scales. In this talk, we will discuss recent efforts within our laboratory to address the influence of the local pH on the CO2 reduction reaction at the atomistic level. We focus the discussion on the binding of CO, a key reaction intermediate in the CO2 reduction pathway, whose preferential hydrogenation or dimerization leads to the production of C1 and C2 products, respectively. We additionally demonstrate how the use of hybrid approaches employing density functional theory (DFT) and continuum models can help bridge time and length scales within the context of atomistic CO2 electroreduction modeling.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.