Nanostructured Au33Pd67
alloy films were fabricated on glass using one-step air
plasma DC magnetron sputtering. The films exhibited highly sensitive detection of
dye molecules (RhB and CV) by the surface-enhanced Raman scattering (SERS).
The synthesized films also showed good catalytic properties for the reduction in
4-nitrophenol at pH ≈ 9.8. Such unique characteristic of the films was linked to the
evolution of nanostructure, which can be controlled simply by the sputtering time.
At the shorter sputtering time (10 and 20 s), the film was composed of isolated particles.
By increasing the sputtering time (30 and 40 s), agglomeration of such nanoparticles
resulted in the formation of the partially connected island nanostructures
(about 38 nm) which can be confirmed by TEM and electrical resistivity measurement.
The detection limit of 1 × 10–12 M RhB and 1 × 10–8 M CV with an enhancement
factor of 7 × 107 and 3.3 × 104, respectively, was achieved over the film synthesized
at the sputtering time of 30 s. The high sensitivity of this film can be ascribed
to the strong electromagnetic field at the junction spots formed between the two
adjacent islands. Moreover, this film has a slightly lower SERS, and better catalytic
properties, in contrast to Au (30 s) film. Finally, the film providing efficient SERS
enhancement is not the most active catalyst. Unlike the SERS, the catalytic activity
depends highly on the amount of AuPd deposited.