Experimental and theoretical investigation on photocatalytic activities of 1D Ag/Ag₂WO₄ nanostructures

Ag₂WO₄ is a significant photocatalyst that responds to UV light irradiation only, which greatly hinders it for further practical application for solar light. To address this problem, herein, 1D plasmonic Ag/Ag₂WO₄ photocatalysts have been fabricated by a successive process including hydrothermal synthesis to obtain Ag₂WO₄ followed by an additional in situ chemical-reduction process for Ag decoration. Then, the structural features, optical properties, and electronic structures of Ag₂WO₄ and Ag/Ag₂WO₄ nanowires were systematically investigated via a combination of theoretical calculations and experimental evidence. The plasmon-enhanced Ag/Ag₂WO₄ nanowires exhibited higher visible-light-driven photocatalytic activity, which performed a desired photodestruction ratio of 91.2% on methylene blue within 60 min and good stability in five cycles. The Ag decoration greatly facilitates visible-light harvesting and thus promotes photogenerated radical oxidation to dye, which is evidenced by the higher hydroxyl radical level of Ag/Ag₂WO₄ detected in the ESR test during the photocatalytic process. The theoretical calculation based on density functional theory indicates that Ag nanoparticles formed on the surface of Ag₂WO₄ could narrow the band gap of Ag₂WO₄. In addition, the surface plasmon resonance absorption effect and fast charge transfer effect in the metal-semiconductor system contribute to the photocatalytic performance of Ag/Ag₂WO₄.