Nb Implanted BaO as a Support for Gold Single Atoms

TL;DR

This study demonstrates through first-principles modeling that Nb-doped BaO can effectively stabilize gold single atoms by charge transfer, preventing agglomeration and enabling new support techniques for noble metals.

Contribution

It introduces a novel method of stabilizing gold single atoms on transition metal-doped oxides, specifically Nb-doped BaO, using charge transfer mechanisms.

Findings

Au atoms are stabilized by charge transfer from Nb dopants.

Charged Au atoms repel each other, maintaining atomic dispersion.

Interstitial Nb doping can bind more Au atoms than substitutional doping.

Abstract

Using first-principles modelling based on density functional theory we show that oxides implanted with transition metal can act as support for Au single atoms, which are stable against agglomeration. In our previous work we have shown that implanted transition metal, doped in BaO is stable as interstitial in various charge states by transferring the excess charge to an acceptor level close to VBM. Taking Nb as an example we show that single atom Au has its Fermi level close to the VBM of BaO and hence is able to accept charge from the dopant. This charge transfer process between Nb and Au helps Au atoms bind strongly on the doped BaO support. We also show that these charged Au atoms repel each other and prefer to remain atomically dispersed preventing cluster formation. Substitutional doping of transition metals have earlier been reported to bind Au atoms. However, if doped at interstitial sites, they can bind more Au atoms; for example, 5 Au atoms can be anchored per Nb dopant present in BaO interstitial, compared to 3 Au atoms when Nb is doped at substitutional site. This work paves the way for an altogether new technique of stabilizing noble metal single atoms on transition metal doped oxides.