Surface Composition Evolution of Bimetallic Alloys under Reaction Conditions

Surface composition is a critical factor determining the chemical and physical properties of bimetallic alloys, which highly depends on the alloy surface segregation behaviors. Recent in situ experiments revealed the dynamic and reversible alloy segregation changes in reaction conditions, leading to distinctive catalytic performances. Thus, how to predict and control the surface composition during catalytic reactions becomes crucial for nanoalloy catalysts. However, the experimental results are mostly complicated and sometimes contradictory, which can hardly be understood by current theoretical models. Herein, we propose an environmental segregation energy (Eeseg), which precisely describes the surface segregation behavior at a given temperature and gas pressure. Using CO as a probe, we reveal insights into the flexible alloy segregation trends under changing gas conditions and perfectly explain the existing experimental results. The surface composition evolutions of 72 binary alloys under various CO conditions are presented in the segregation maps. This work provides a guide to high-throughput prescreening of the desired surface composition under optimal conditions, which paves the way for tuning the alloy structure in real catalytic reactions.