Understanding the activity of single atom catalysts for CO2 reduction to C2 products: A high throughput computational screening

Abstract

The tunable electronic structure of the central metal atoms in single-atom catalysts (SACs) helps to control the adsorption energy of reactants and different reaction intermediates involved in multistep chemical processes. Although SACs have been recently proposed to be effective for electrochemical CO₂ reduction to C₁ products such as HCOOH, CH₃OH and CH₄, their role in catalysing CO₂ reduction to C₂ products involving more complex reaction pathways is largely unknown. Herein, by means of systematic first-principles simulations, we thoroughly evaluate a total of 27 transition metal-based SACs supported on a g-C₂N monolayer for CO₂ reduction to C₂ products such as ethene and ethanol. Our results demonstrate that the SACs reveal limiting potential values ranging from −1.50 to −2.70 V and are capable of effectively suppressing the competitive hydrogen evolution reaction. The most effective candidates capable of reducing CO₂ to C₂ products were found to be Cu@C₂N, Cr@C₂N, and Fe@C₂N exhibiting limiting potential values of −1.50, −2.23, and −2.27 V, respectively. We further find that the catalytic activities of all the SACs can be correlated with the adsorption free energy of one of the intermediate species (*COCH₂O) making it a suitable descriptor for evaluating their CO₂ reduction activity. Hence, this study provides key inputs regarding CO₂ conversion to C₂ products on SACs and is expected to lead to further explorations for future design of SACs for the formation of multicarbon products.