Dopant-Dependent Boron Arrangement and Chemistry of Metal Boride Surface

Borides, an emerging family of materials with rich and diverse stoichiometries and structures, have exhibited boron-dependent catalytic properties where boron instead of the metal governs the surface chemistry. However, boron motifs are inherently polymorphic and can be prone to fluxional rearrangement, making it difficult to resolve or control the active site structures. Here, we show that metal doping can direct the arrangement of surface boron and thereby tune the accessible surface boron configurations. Using extensive global optimization searches combined with ab initio thermodynamics, we identify synthesizable surface phases across a range of surface boron stoichiometries. The resulting surfaces display a wealth of geometric and electronic structures, whose origins are traced to dopant-stabilized boron rearrangements. These nonuniform multisite surfaces bind different adsorbates through distinct modes, thus making it impossible to comply with conventional catalysis models such as scaling relations. We further demonstrate that multiobjective searches can efficiently navigate this chemical space and reveal candidates that deliberately escape traditional activity-selectivity-durability trade-offs. The results establish a promising catalyst system with highly controllable reactivity enabled by dopant-dependent boron arrangements, and provide a generalizable workflow for other fluxional catalytic systems.