Theoretical evidence for new adsorption sites of CO$_2$ on the Ag electrode surface

TL;DR

This paper uses density functional theory to identify new preferred adsorption sites for CO₂ on silver electrodes, revealing terrace sites are more favorable than previously thought, which impacts understanding of CO₂ electroreduction.

Contribution

It provides the first theoretical evidence that terrace sites are the dominant adsorption sites for CO₂ on Ag surfaces, challenging prior assumptions about step sites.

Findings

Terrace sites are the preferred adsorption sites for CO₂ on Ag surfaces.

Adsorption populations follow the order (211) > (110) > (111) > (100).

Adsorption characteristics correlate with d-band theory and charge transfer analysis.

Abstract

Nowadays, electrochemical reduction of CO$_2$ has been considered as an effective method to solve the problem of global warming. The primary challenge in studying the mechanism is to determine the adsorption states of CO$_2$, since complicated metal surfaces often result in many different adsorption sites. Based on the density functional theory (DFT) calculations, we performed a theoretical study on the adsorption of CO$_2$ on the Ag electrode surface. The results show that the adsorption populations of CO$_2$ are extremely sensitive to the adsorption sites. Importantly, we found that the preferable adsorption positions are the terrace sites, rather than the previous reported step sites. The adsorption populations were found with the order of (211) > (110) > (111) > (100). Subsequently, the adsorption characteristics were correlated with the d-band theory and the charge transfers between Ag surfaces and CO$_2$.