Plasmon resonance-based photoelectrochemical tailoring of spectrum, morphology and orientation of Ag nanoparticles on TiO2 single crystals

Abstract

Simultaneous irradiation of a single crystal TiO₂ substrate in solution by filtered UV and filtered visible light is employed to control the colour, size and orientation of Ag nanoparticle monolayers. Particle growth by photocatalytic reduction of Ag⁺ to Ag is kept in check by plasmon-assisted photooxidation of Ag to Ag⁺. As a result, red samples with small Ag nanoparticles, blue samples with large Ag nanoparticles or samples with aligned nanorods are obtained. Computer simulations of the spectra elucidate that growth of anisotropic particles is essential to exhibit a brilliant blue colour.