Boron atoms boring into metal nanoparticles

Abstract

Boron can be intentionally or unintentionally incorporated into transition metal (TM) surfaces when borohydride, boric acid, or diborane are used during materials synthesis. As a result, boron treatment could strongly affect the properties of many TM catalysts. In this study, we employ density functional (DFT) calculations to investigate the thermodynamics and kinetics of boron incorporation into ~1.5 nm particles and extended (111) surfaces of fcc metals, namely, Ir, Rh, Ni, Pd, Pt, Cu, Ag, Au, and Al. Our results reveal that boron exhibits high thermodynamic stability in interstitial subsurface sites of (111) surfaces and nanoparticles (NPs) of Rh, Pt, and Pd. In addition, we find a new type of “in-surface” sites for B incorporation between surface atoms in nanostructured metals, which is highly stable in Rh, Ir, and Ni NPs. Furthermore, nanostructuring decreases the activation energies of boron incorporation to <0.4 eV on all metals except Ir. Notably, B incorporation induces significant charges and d-band center shifts in adjacent metal atoms, which indicates its pronounced impact on the catalytic activity of all considered transition metals.