Plasmon-resonance-based generation of cathodic photocurrent at electrodeposited gold nanoparticles coated with TiO2 films.

Reversed photoresponse: Indium tin oxide (ITO)/Au nanoparticle (NP)/TiO2 electrodes (see picture) exhibit cathodic photocurrents and positive photopotentials under visible light, whereas ITO/TiO2/Au NP electrodes show an inverted response. This behavior indicates that electron transfer occurs from the plasmon-excited Au NPs to the TiO2 film. An enhanced O2 photoreduction activity is found for ITO/Au NP/TiO2/Pt electrodes.