(707b) Dopant-Dependent Arrangement and Chemistry of Surface B on Metal Diborides

Boron’s polymorphism enables a diverse range of metal boride structures, from intermetallic-like phases to covalent networks. Their stability, electronic properties, and catalytic activity are highly B-dependent, dictated by boron content and coordination. This structural and electronic tunability underpins the versatile reactivity of metal borides for various applications.

In this work, we study the surface doping and B-enriching treatment of metal diboride surfaces. We found that the surface B arrangement depend strongly on the chemical identity of the dopant, leading to polymorphism even at the same B stoichiometry. Upon B-enriching, the surface B arrangement further complicates. The chemical space is sampled by grand canonical global optimization with respect to B, and the synthesizable phases are predicted from ab initio thermodynamics. Those phases, with diverse structural motifs of B, exhibit diverse chemistry as well, as is characterized by a huge variation of adsorption energetics for various common adsorbates. This means that doped metal borides can be a promising model catalysts family with surprisingly high tenability, and all these space can be unlocked by surface B rearrangements.