Connecting structural, optical, and electronic properties and photocatalytic activity of Ag3PO4:Mo complemented by DFT calculations

Abstract

The present join experimental and theoretical work provides in-depth understanding on the relationship among structural, optical, and electronic properties and photocatalytic activity of Ag3PO4:Mo microcrystals. We prepared Ag3PO4 and (Mo-doped) Ag3PO4:Mo microcrystals using the chemical precipitation method. The as-synthetized samples have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, transmission electron microscopy, high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray spectroscopy (EDS) techniques, and photoluminescence (PL) emission. Density functional theory calculations have been performed to complement the experimental results and understand the physical phenomena taking place in the structure, electronic and optical properties involved in the Mo doping process on the Ag3PO4, and consequently the photocatalytic performances of these new materials. XRD analysis showed that at a doping level below 2% the samples did not present any secondary phases, demonstrating that the Mo cations have been actually incorporated in the Ag3PO4 structure. Moreover, HAADF-STEM and EDS mapping showed that the samples were homogeneous, especially with respect to the Mo cations, and showed no signs of segregation. The Egap value and PL measurements indicated that the doping process caused structural defects in the Ag3PO4 structure. The photocatalytic activity of both the pure and Mo-doped materials was tested for the degradation of Rhodamine B under visible light irradiation. The results demonstrated that the sample of Ag3PO4:Mo with 0.5% Mo had a faster degradation rate, approximately 92% after 5 min of irradiation, while the degradation rate of the pure sample was only 46% during the same time.