Figure 2

Scanning electron micrographs of the surface morphologies of different layers of the samples.

(a) FTO glass; (b) Au NPs on FTO glass, deposited by the sputtering process; (c) rough Au film on FTO glass; (d) ALD-deposited TiO₂ film on the rough Au film. The inset in (b) is the histogram of the size of Au NPs.