Investigation of stability of O atom adsorption on silver-based single atom alloys for potential fuel cell applications

Abstract

Anion exchange membrane fuel cell (AEMFC) is an attractive alternative to proton exchange membrane fuel cell (PEMFC). Unlike PEMFC, AEMFC shows an increase in oxidation reduction reaction (ORR) activity and uses low-cost catalysts, namely silver-based materials. Researchers have explored different structures and compositions for silver-based catalysts but there are still catalytic structures that haven’t been extensively studied for ORR. For instance, one type of alloy that has been shown to have significantly improved the catalytic performance of the host material is called single-atom alloys (SAA). Thus, we conducted a density functional theory study about the behavior of O adsorption on silver-based SAA surfaces (X-Ag(111)  where the dopant atom X = Au, Cu, Ir, Ni, Pd, Pt, Co, Rh).  Our results show that O adsorption was stronger on X-Ag(111) systems compared to the pristine Ag(111). Furthermore, we observed that O preferred to bond with the dopant atom for most of the X-Ag(111). Among the X-Ag(111) surfaces, the strongest and weakest O adsorption were measured on Co-Ag(111) and Au-Ag(111), respectively. Charge density difference of the adsorbed O and X-Ag(111) shows  that the adsorption strength of O depends on its interaction with the dopant atom X. Thus, these findings show the potential of silver-based SAA as a catalyst for ORR.