Realization of interstitial boron ordering and optimal near-surface electronic structure in Pd-B alloy electrocatalysts

Abstract

The fundamental understanding and precise tuning of interatomic s,p-d orbital hybridization are critical to the design of interstitial alloy catalysts containing light constituent atoms. Here, we present a joint theoretical and experimental study that reveals the importance of distribution, concentration and ordering of interstitial boron atoms in Pd-B alloy’s near-surface electronic structure and catalytic performance. Our theoretical results demonstrate that the sub-surface location of interstitial boron atoms with a Pd:B atomic ratio of 2:1 is necessary to ensure an appropriate degree of interatomic s,p-d orbital hybridization, and thereby an optimal surface electronic structure for the hydrogen evolution reaction (HER). We experimentally achieve this with highly-crystalline intermetallic Pd2B. Due to its optimal electronic structure and ordered arrangement of interstitial boron atoms, the intermetallic Pd2B exhibits Pt-like catalytic activity for HER and has excellent catalytic stability for over seven days.