Thin silica shell on Ag3PO4 nanoparticles augments stability and photocatalytic reusability

Abstract

Semiconductor photocatalysts are promising cost-effective materials for degrading hazardous organic contaminants in water. Ag₃PO₄ is an efficient visible-light photocatalyst for the oxidation of water and dye degradation. The excited Ag₃PO₄ photocatalyst uses a hole to oxidise water or organic contaminants except the electron, which reduces Ag⁺ to Ag⁰. In the present study, the inherited disadvantage was overcome by a thin silica shell overcoating on Ag₃PO₄ nanoparticles. The silica-coated Ag₃PO₄ nanoparticles retain the photocatalytic activity even after five cycles of photodegradation, while the bare Ag₃PO₄ nanoparticles show a photocatalytic activity declined to half. The study demonstrates that the thin silica shell enhances the photostability, keeping the photocatalytic activity unaffected, even after several cycles of photodegradation of dyes. XPS analysis showed that the Ag⁰ formation on the surface of bare Ag₃PO₄ is greater than that on silica-coated Ag₃PO₄, which declines the photocatalytic activity of Ag₃PO₄ after five cycles of photodegradation. Electrochemical studies identified that the intermediates, such as OH˙ and O₂⁻, formed during water oxidation play a crucial role in the photodegradation of dyes. This study can provide insights into the design of core–shell semiconductor nanostructures for reusable photocatalytic applications.