Synthesis and Application of Silver Phosphate as Photocatalyst

Original Article:
Silver phosphate Ag3PO4 is a photocatalyst that can be excited by visible light. The article reviews applications and synthesis methods of silver phosphate as photocatalyst. Alfa Chemistry supplies high-quality silver phosphate for research use.

Qingfa Tan, et al.

Chem. Commun., 2021,57, 3018-3021

10.1039/D1CC00262G

Silver phosphate (Ag₃PO₄) is a photocatalyst that can be excited by visible light, and its band gap energy is about 2.43 eV. In general, pure Ag₃PO₄ photocatalysts can absorb solar energy with wavelengths less than 530 nm. In addition, Ag₃PO₄ has strong oxidizing properties, and its quantum efficiency in water oxidation can reach about 90%. Ag₃PO₄ has been widely reported as a photocatalyst to treat environmental pollutants, such as phenol and phenol derivatives, humic acid, Cr (VI), dyes, endocrine disrupting compounds, pharmaceuticals and personal care products, etc. In this work, the authors summarize a variety of synthetic methods for silver phosphate photocatalysts.

Factors Affecting the Synthesis of Ag₃PO₄-Based Photocatalysts

There are four basic steps in the photocatalytic process: generation of electron-hole pairs, photoinduced separation of electron-hole pairs, migration of electron-hole pairs to the surface, and redox reactions. The migration of electron-hole pairs to surface processes is usually affected by particle size, surface state, crystallinity, crystal structure, etc.

Methods For Ag₃PO₄-Based Photocatalyst Synthesis

• Ion-exchange method
  The ion exchange method is the most commonly used method to prepare Ag₃PO₄. It utilizes the different solubility of raw materials such as AgM and NPO4 (M and N are ions or ion groups other than Ag⁺ and PO₄^3- respectively), and replaces M or N³⁺ with PO₄^3- or Ag⁺ to form Ag₃PO₄ particles.

Schematic illustration of the ion exchange method from Ag₂WO₄.

• Precipitation method
  The precipitation method is also commonly used in the manufacture of Ag₃PO₄. Past studies have shown that samples prepared by precipitation method have higher photooxidative ability in degrading humic acid than those prepared by ion exchange method.
• Hydrothermal method
  By controlling the basic synthesis parameters such as hydrothermal temperature and pressure strength, the hydrothermal method can obtain Ag₃PO₄ products with few defects, good directionality, regular shape and high purity.
• Colloidal method
  The Ag₃PO₄ samples prepared by the colloidal method were uniformly spherical and well-distributed. Experiments show that under the same conditions, the photocatalytic ability of the sample prepared by the colloid method is 2.6 times that of the sample prepared by the precipitation method.
• Heteroepitaxial growth method
  Researchers have prepared concave trioctahedral Ag₃PO₄ crystallites surrounded by {221} and {332} facets by heteroepitaxial growth method. High-index faces typically have an extremely high density of atomic steps, flanges, kinks, dangling bonds, and higher chemical reactivity compared to low-index faces.

Chemicals Related in the Paper:

Catalog Number	Product Name	CAS Number
ACM7784090	Silver phosphate, 98%	7784-09-0