Synergistic Piezoelectric-Nanoscale Zero-Valent Iron Catalyst for Peroxyacetic Acid Activation: A Self-Driven Advanced Oxidation Process

Conventional advanced oxidation processes (AOPs) that utilize iron-based catalysts encounter several limitations, including rapid deactivation and low electron transfer efficiency. Although piezoelectric materials have shown potential for mechanochemical energy conversion, their practical application is often hindered by the need for substantial external energy inputs. This requirement results in considerable energy consumption and waste. Herein, we innovatively designed a symbiotic self-driven nZVI@BTO catalyst through dual incorporation of nZVI within the barium titanate (BTO) lattice and its surface, achieving breakthrough synergy between piezoelectric activation and peracetic acid (PAA)-mediated oxidation. The nZVI@BTO/PAA system completely degraded sulfamethoxazole (SMX) within 10 min, exhibiting 12-fold enhancement in k_obs compared to the nZVI/PAA system. The hydraulic vortex-induced piezoelectric polarization of nZVI@BTO generated a surface-enhanced built-in electric field (BIEF), creating a localized reducing microenvironment. This enhanced charge carrier separation and promoted the efficient regeneration of Fe²⁺, ensuring a sustained abundance of active Fe²⁺ sites on the catalyst surface. Surface Fe²⁺ sites enabled rapid PAA activation, generating hydroxyl radical (^•OH), singlet oxygen (¹O₂), and acetylperoxy radical (CH₃C(O)OO^•). Our findings demonstrated the efficiency, stability (maintaining >80% SMX removal after 5 cycles), and practicality of the nZVI@BTO/PAA system for real-world applications. The nZVI@BTO/PAA system represented a sustainable strategy for AOPs, advancing the development of environmentally resilient water treatment technologies.