Rational Design of W-Doped Ag₃PO₄ as an Efficient Antibacterial Agent and Photocatalyst for Organic Pollutant Degradation

Abstract

Bacterial and organic pollutants are major problems with potential adverse impacts on human health and the environment. A promising strategy to alleviate these impacts consists in designing innovative photocatalysts with a wider spectrum of application. In this paper, we report the improved photocatalytic and antibacterial activities of chemically precipitated Ag₃PO₄ microcrystals by the incorporation of W at doping levels 0.5, 1, and 2 mol %. The presence of W directly influences the crystallization of Ag₃PO₄, affecting the morphology, particle size, and surface area of the microcrystals. Also, the characterization via experimental and theoretical approaches evidenced a high density of disordered [AgO₄], [PO₄], and [WO₄] structural clusters due to the substitution of P⁵⁺ by W⁶⁺ into the Ag₃PO₄ lattice. This leads to new defect-related energy states, which decreases the band gap energy of the materials (from 2.27 to 2.04 eV) and delays the recombination of e'-h^• pairs, leading to an enhanced degradation process. As a result of such behaviors, W-doped Ag₃PO₄ (Ag₃PO₄:W) is a better visible-light photocatalyst than Ag₃PO₄, demonstrated here by the photodegradation of potential environmental pollutants. The degradation of rhodamine B dye was 100% in 4 min for Ag₃PO₄:W 1%, and for Ag₃PO₄, the obtained result was 90% of degradation in 15 min of reaction. Ag₃PO₄:W 1% allowed the total degradation of cephalexin antibiotic in only 4 min, whereas pure Ag₃PO₄ took 20 min to achieve the same result. For the degradation of imidacloprid insecticide, Ag₃PO₄:W 1% allowed 90% of degradation, whereas Ag₃PO₄ allowed 40%, both in 20 min of reaction. Moreover, the presence of W-dopant results in a 16-fold improvement of bactericidal performance against methicillin-resistant <i>Staphylococcus aureus</i>. The outstanding results using the Ag₃PO₄:W material demonstrated its potential multifunctionality for the control of organic pollutants and bacteria in environmental applications.