Synergistic oxidation and reduction of complex pollutants in wastewater using a self-cycling piezo-photocatalytic...

Simultaneous organic pollutant oxidation and heavy metal ion reduction may enhance ocean and medical wastewater treatment. Here a self-cycling piezo-photocatalytic Fenton (SPF) system was developed using an Na-Sm bimetal-doped layered ferroelectric perovskite SrBi₂Nb₂O₉ (NS-SBNO) and Fe^2 + ions. The experimental results and density functional theory calculations demonstrated that bimetal doping induced an enhanced internal electric field, improving electron-hole pair separation and transmission. NS-SBNO exhibited increased adsorption energy and electron transfer capacity of H₂O, leading to H₂O₂ production at 497 μmol g^-1 h^-1 through a two-electron water oxidation reaction without any sacrificial reagent. Furthermore, compared with traditional Fenton systems, the SPF system afforded higher Fe²⁺/Fe³⁺ interconversion efficiency and hydroxyl and superoxide radical yields, highlighting the system's excellent redox capabilities. The SPF system also demonstrated enhanced oxidation and reduction of complex pollutants in wastewater [e.g., BPA, TC, 2, 4-DCP, NOR, LVX, U(VI), and Cr(VI)], demonstrating promising practical applicability.