  The interaction of oxygen with noble metals such as silver has been an
important topic of research for many decades. Here, we show occurrence of a
peak in the density of states (DOS) at the Fermi level ($E_F$) when oxygen
atoms occupy disordered substitutional positions in noble metals such as Ag, Au
or Ag-Au alloy. This results in large enhancement of DOS at $E_F$ with respect
to Ag or Au metal. Its origin is attributed to O 2$p$ related disorder
broadened flat band that straddles almost all the high symmetry directions of
the Brillouin zone. Our work suggests that if a large concentration of
disordered oxygen can be realized in nano-structures of noble metals, it may
lead to interesting phenomenon.

Materials Science