  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.
