Plasmon-enhanced Catalytic Ozonation for Efficient Removal of Recalcitrant Water Pollutants

Abstract

Ag-Doped MnFe2O4 catalyst (Ag/MnFe2O4) was synthesized by a simple sol–gel method followed by H2 reduction. Utilizing the localized surface plasmon resonance (LSPR) of Ag, ∼35-fold and ∼7-fold degradation rate increases for a representative ozone-resistant water pollutant (atrazine) were achieved with a low photon flux (∼10–10 Einstein L–1), as compared to ozonation and catalytic ozonation, respectively, which also outperformed the homogeneous peroxone (O3/H2O2) process. The plasmon-mediated enhancement was realized through energy transferred from plasmonic Ag nanostructures to ozone adsorptive sites during the LSPR decay, leading to an accelerated ozone decomposition and subsequent radical generation (e.g., ·OH, O2·–, and 1O2) at both existing and newly activated catalytic active sites. Ag LSPR also helps maintain Ag0 in an oxidizing aqueous environment, which is crucial to sustain the high catalytic activity. Because of these plasmonic effects, more than 90% removal was achieved in tap water under realistic water treatment conditions.