Role of Bismuth Topological and Trivial Surface States in Molecular Adsorption.

Topological materials have recently been proposed as a new class of catalysts, where robust surface states near the Fermi level are expected to influence adsorption and reactivity. In this Letter, using first-principles calculations, we systematically investigate molecular adsorption on bismuth (Bi) slabs across a wide range of adsorbates, spanning both trivial and topological electronic regimes. We find that open-shell adsorbates strongly hybridize with both topological and trivial surface states near the Fermi energy. Although adsorption is primarily governed by conventional chemical bonding, we quantitatively assess how surface states modulate binding energetics by comparing slabs (with surface states) to a monolayer. The COHP analysis further confirms that surface-state hybridization strongly reshapes the bonding and antibonding contributions near the Fermi level, thereby modulating the adsorption energetics. This framework also qualitatively accounts for the distinct catalytic performance between bulk-like slabs and monolayer Bi. Overall, topological character appears to play a more indirect role, while a surface-state-centric perspective may provide a useful framework for understanding catalytic behavior.