Fabrication of visible-light-driven Ag/TiO₂ heterojunction composites induced by shock wave

Using metatitanic acid (H₂TiO₃) and silver nitrate (AgNO₃) as titanium precursor and silver source respectively, a visible-light responsible Ag/TiO₂ heterojunction photocatalyst is successfully prepared by shock wave with detonation-driven flyer impact. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence (PL) emission spectra are employed to characterize the phase structure, morphology, chemical composition and optical property of the recovered samples. The results indicate the metatitanic acid transforms to pure rutile TiO₂ phase by shock wave which possess large surface area. Ag nanoparticles cover on the surface of TiO₂ uniformly and a nanojunction structure is formed efficiently, which play important roles as an electron-conduction bridge and in the surface plasmon resonance effect. Ag modification feasibly improves the separation efficiency for photoinduced electron-hole pairs and enhances the visible-light response. Furthermore, due to the further enhanced separation for photogenerated charges resulting from close interfacial contact of the hetero structure, the obtained Ag/TiO₂ photocatalyst exhibit remarkably improved photocatalytic activities (88% within 2 h) than that of P25 and shock induced pure TiO₂ for the degradation of Rhodamine B under simulated sunlight irradiation. The experimental result shows the shock loading is an effective method to get Ag/TiO₂ photocatalyst and offers new ideas to fabricate other heterojunction composite materials.