Visible light driven photoelectrochemical properties of Ti@TiO2 nanowire electrodes sensitized with core-shell Ag@Ag2S nanoparticles.

We present a model electrode system comprised of nanostructured Ti electrode sensitized with Ag@Ag2S core-shell nanoparticles (NPs) for visible light driven photoelectrochemistry studies. The nanostructured Ti electrode is coated with Ti@TiO2 nanowires (NW) to provide a high surface area for improved light absorption and efficient charge collection from the Ag@Ag2S NPs. Pronounced photoelectrochemical responses of Ag@Ag2S NPs under visible light were obtained and attributed to collective contributions of visible light sensitivity of Ag2S, the local field enhancement of Ag surface plasmon, enhanced charge collection by Ti@TiO2 NWs, and the high surface area of the nanostructured electrode system. The shell thickness and core size of the Ag@Ag2S core-shell structure can be controlled to achieve optimal photoelectrochemical performance. XPS, XRD, SEM, high resolution TEM, AC impedance, and other electrochemical methods are applied to resolve the structure-function relationship of the nanostructured Ag@Ag2S NP electrode.