Photocatalytic activity of Ag@AgI sensitized K2Ti4O9 nanoparticles under visible light irradiation

Plasmonic Ag@AgI-sensitized K2Ti4O9 composite photocatalysts (hereafter designated as Ag@AgI/K2Ti4O9) were synthesized via a facile hydrothermal deposition-photoreduction method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis), X-ray photoelectron spectroscopy (XPS), etc. The synthesized Ag@AgI in the composite photocatalyst possessed hexagonal structure, while the K2Ti4O9 crystal was monoclinic. The size of Ag@AgI nanoparticles, which were uniformly scattered on the surface of K2Ti4O9, was distributed in the range of 100–200 nm. The prepared Ag@AgI/K2Ti4O9 samples also exhibited superior visible light absorption compared to the pure K2Ti4O9. The photocatalytic activity of the prepared materials for organics degradation was examined under visible light irradiation, and the effect of Ag@AgI loading amount was studied and was found to influence the absorption spectra observed. The Ag@AgI (15 wt.%)/K2Ti4O9 composite photocatalyst synthesized by hydrothermal-deposition-photoreduction method exhibited the highest photocatalytic activity, degrading 95.26% of methylene blue (MB) after 2 h of irradiation. The catalyst stability was also investigated. The high photocatalytic activity of the prepared composite can be attributed to the surface plasmon resonance effect of Ag nanoparticles and synergy with the layered host material, and a mechanism of photocatalysis was discussed.