Experimental and Theoretical Study on the Structure, Optical Properties, and Growth of Metallic Silver Nanostructures in Ag₃PO₄

Abstract

Theoretical and experimental studies were performed on the structure, optical properties, and growth of silver nanostructures in silver phosphate (Ag 3 PO 4 ). This material was synthesized by the coprecipitation method and processed in a microwave-assisted hydrothermal system at 150 °C for different times. The structural behavior was analyzed by means of X-ray diffraction, Rietveld refinement, and Raman spectroscopy. Field emission gun scanning electron microscopy as well as transmission electron microscopy revealed the presence of irregular spherical-like Ag 3 PO 4 microparticles; metallic silver nanostructures were found on their surfaces. The growth processes of Ag nanostructures when irradiated with an electron beam were explained by theoretical calculations. First-principles calculations, within a quantum theory of atoms in molecules framework, have been carried out to provide deeper insight and understanding of the observed nucleation and early evolution of Ag nanoparticles on Ag 3 PO 4 crystals, driven by an accelerated electron beam from an electronic microscope under high vacuum. The Ag nucleation and formation is a result of structural and electronic changes of the AgO 4 tetrahedral cluster as a constituent building block of Ag 3 PO 4 , consistent with Ag metallic formation. The optical properties were investigated by ultraviolet−visible spectroscopy and photoluminescence (PL) measurements at room temperature. PL properties of this phosphate were explained by the recombination phenomenon of electron−hole pairs via cluster-to-cluster charge transfer.

Photoluminescence and Photocatalytic Properties of Ag3PO4 Microcrystals: An Experimental and Theoretical Investigation

“…The E gap value of 2.2 eV is in good agreement with results reported in the literature . The calculated indirect band gap (M−Γ) is 2.72 eV, which is higher than the value reported in other studies by using a similar methodology, that is, from 2.13 to 2.36, 2.43, and 2.49 eV . The Brillouin zone with the path used, as well as the band structure and DOS projected on atoms, are presented in Figure b.…”

“…performed a morphology‐controlled synthesis, by deposition–precipitation in the presence of ammonia, of Ag 3 PO 4 microcubes with enhanced visible‐light‐driven photocatalytic activity . Recently, we published an experimental and theoretical study on the structure, optical properties, and growth of metallic silver nanostructures in Ag 3 PO 4 …”

In Situ Photoactivated Plasmonic Ag3PO4@silver as a Stable Catalyst With Enhanced Photocatalytic Activity Under Visible Light

“…As can be seen, pure Ag 3 PO 4 exhibits a steep absorption edge in the UV and visible range shorter than 530 nm. According to the previous document 16 , the strong absorption below a wavelength of 530 nm is associated with the optical band gap of Ag 3 PO 4 . The indirect band gap of Ag 3 PO 4 is estimated to be 2.32 eV, as well as, direct transition is 2.40 eV.…”

Insights Into Highly Improved Solar-Driven Photocatalytic Oxygen Evolution Over Integrated Ag3PO4/MoS2 Heterostructures

“…The peak at 1002.4 cm −1 is ascribed to the asymmetric stretching vibrations of O–P–O bonds in [PO 4 ] clusters. The broad peak located at 554.4 cm −1 arises from the asymmetric stretch of P–O–P bonds, while the peak centered at 406.1 cm −1 corresponds to the symmetric bending vibration modes related to [PO 4 ] clusters (Botelho et al, 2015). For pure MoS 2 , characteristic Raman shifts located at 375.8 and 402.1 cm −1 are assigned to the E 2g and A 1g modes, while the peak appearing at 446.2 cm −1 is suggested to come from the interaction of the longitudinal acoustic phonon and Raman inactive A 2u modes (Koroteev et al, 2011; Lukowski et al, 2013).…”