Fabrication and photoelectrochemical study of Ag@TiO2 nanoparticle thin film electrode

Ag@TiO2 nanoparticle thin film was fabricated for photoelectrochemical water splitting in the visible light region. Under the irradiation of UV light, positive photocurrent was enhanced in both electrolytes of 0.1 M HNO3 and 0.1 M NaOH owing to the excitation of photoelectrons within the TiO2 shells. However, under the irradiation of visible light, the enhancement of positive photocurrent was observed only in 0.1 M HNO3 because of the formation of a Schottky barrier band bending at the Ag–TiO2 core-shell interface and the generation of photoelectrons resulted from the surface plasmon resonance of Ag cores. In 0.1 M NaOH, significant negative photocurrent was enhanced due to the influences of higher pH on the surface state and energy level of TiO2 shells. Such a visible light-induced photoresponse enhancement and photocurrent direction switching made the Ag@TiO2 nanoparticle thin film useful not only as a photoelectrode for water splitting but also as a photo-switch in a basic electrolyte.

► Ag@TiO2 nanoparticle thin film was fabricated for photoelectrochemical water splitting.
► Positive photocurrent was enhanced under the irradiation of UV light.
► Visible light irradiation induced photocurrent direction switching in a basic electrolyte.