Potential to stabilize 16-vertex tetrahedral coinage-metal cluster architectures related to Au20

Abstract

DFT calculations were carried out on a series of tetrahedral 16-atom superatomic clusters having 20 or 18 jellium electrons (je) and structurally related to Au₂₀, namely, [M₁₆]^4−/2− (M = Cu, Ag, and Au) and [M₄′M₁₂′′]^0/2+ (M′ = Zn, Cd, Hg; M′′ = Cu, Ag, Au). While the bare homonuclear 20-je species required further stabilization to be isolated, their 18-je counterparts exhibited better stability. Lowering the electron count led to structural modification from a compact structure (20-je) to a hollow sphere (18-je). Such a change could be potentially controlled by tuning redox properties. Among the 20-je heteronuclear [M₄′M₁₂′′] neutral series, [Zn₄Au₁₂] appeared to meet the best stability criteria, but their 18-je relatives [M₄′M₁₂′′]⁺, in particular [Zn₄Cu₁₂]²⁺ and [Cd₄Au₁₂]²⁺, offered better opportunities for obtaining stable species. Such species exhibit the smallest models for the M(111) surface of fcc metals, which expose designing rules towards novel high-dopant-ratio clusters as building blocks of nanostructured materials.