Plasmonic Ag@Ag3(PO4)1−xnanoparticle photosensitized ZnO nanorod-array photoanodes for water oxidation

Abstract

We report the new design of a high-activity model for photocatalytic nanosystem comprising an Ag core covered with an approximately 2 nm thick nanoshell of Ag₃(PO₄)_1–x (Ag@Ag₃(PO₄)_1–x) on the ZnO NRs that are visible-light-sensitive photofunctional electrodes with strong photooxidative capabilities to evolve O₂ from water. The maximum photoconversion efficiency that could be successfully achieved was 2%, with a significant photocurrent of 3.1 mA cm⁻². Furthermore, in addition to achieving a maximum IPCE value of 90%, it should be noted that the IPCE of Ag@Ag₃(PO₄)_1−x photosensitized ZnO photoanodes at the monochromatic wavelength of 400 nm is up to 60%. Our photoelectrochemical performances are comparable to those of many oxide-based photoanodes in recent reports. The improvement in photoactivity of PEC water-splitting may be attributed to the enhanced near-field amplitudes resulting from localized surface plasmon resonance (LSPR) of Ag–core and absorption edge of the Ag₃(PO₄)_1−x nanoshell, which increase the rate of formation of electron–hole pairs at the nearby surface of Ag₃(PO₄)_1−x nanoshell and ZnO nanorod, thus enlarging the amount of photogenerated charge contributing to photocatalysis. The capability of developing highly photoactive Ag@Ag₃(PO₄)_1−x-photosensitized ZnO photoanodes opens up new opportunities in various photocatalytic areas, particularly solar-hydrogen fields.