Fabrication of Z-scheme Ag3PO4/TiO2 Heterostructures for Enhancing Visible Photocatalytic Activity

Abstract

In this paper, a synthetical study of the composite Ag₃PO₄/TiO₂ photocatalyst, synthesized by simple two-step method, is carried out. Supplementary characterization tools such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy were adopted in this research. The outcomes showed that highly crystalline and good morphology can be observed. In the experiment of photocatalytic performance, TiO₂400/Ag₃PO₄ shows the best photocatalytic activity, and the photocatalytic degradation rate reached almost 100% after illuminating for 25 min. The reaction rate constant of TiO₂400/Ag₃PO₄ is the largest, which is 0.02286 min^-1, twice that of Ag₃PO₄ and 6.6 times that of the minimum value of TiO₂400. The degradation effect of TiO₂400/Ag₃PO₄ shows good stability after recycling the photocatalyst four times. Trapping experiments for the active catalytic species reveals that the main factors are holes (h⁺) and superoxide anions (O·- 2), while hydroxyl radical (·OH) plays partially degradation. On this basis, a Z-scheme reaction mechanism of Ag₃PO₄/TiO₂ heterogeneous structure is put forward, and its degradation mechanism is expounded.