Plasmon‐Induced Charge Separation in Au and Ag Nanoparticle–Polyoxometalate Systems

Plasmon‐induced charge separation (PICS), which is based on electron injection from plasmonically excited nanoparticles (NPs) into an electron collector, has predominantly employed wide‐bandgap semiconductors such as TiO ₂ as the electron collector. If polyoxometalates (POMs), which can serve as capping agents to assist the dispersion of plasmonic metal NPs in water, could also function as electron collectors, metal–POM nanocomposites would be promising as photocatalysts. In the present study, commercially available α‐H ₄ SiW ₁₂ O ₄₀ (SiW ₁₂ ) was used as a POM and assembled as thin films on electrodes by a layer‐by‐layer method. PICS via electron injection from Au NPs and that from Ag NPs into SiW ₁₂ was demonstrated by photoelectrochemical measurements and visible absorption spectroscopy, respectively.