(230b) Tuning Reactivity in Trimetallic Dual Atom Alloys: Molecular-like States and Ensemble Effects

Single-atom alloys (SAAs) have drawn significant attention in recent years due to their excellent catalytic properties. Controlling the structure and electronic structure of localized catalytic active sites is of fundamental and technological importance. Dual-atom alloys (DAAs) bring increased tunability and a larger active site, as compared to SAAs. The nature of hetero-DAAs’ catalytic activity needs to be further investigated both theoretically and experimentally. Here, we computationally examined the electronic structure of various SAAs and DAAs. DOS and wavefunctions show that combining two SAAs into a dimer site can result in molecular-like hybridization. This kind of structure not only inherits the small interaction between dopants and hosts, but can also bring new properties due to dopant-dopant interactions, leading to changes in the chemical reactivity of each atom. Furthermore, the formation energy suggests some hetero-dual-atom sites are more stable in the surface than homo-dual-atom sites and single-atom sites, which makes them likely synthesizable. Subsequent experimental studies based on the calculations indeed suggest that heterometallic dual-atom sites can be created. Additionally, when changing from an SAA to a DAA, the CO adsorption energy can be either enhanced or weakened due to electronic effects result from dopant-dopant interactions. On the other hand, ensemble effects can lead to stronger adsorption on bridge sites, providing another strategy to controllably tune the catalytic properties. This work provides insights into DAA’s unique catalytic properties, and opens up new possibilities in design of catalytic active sites for particular reactions.