Ferroelectric Bi2Fe4O9 for efficient peroxymonosulfate activation: The overlooked role of spontaneous polarization

Bi 2 Fe 4 O 9 is a ferroelectric material successfully implemented in advanced oxidation processes to activate peroxymonosulfate (PMS). However, the role of its ferroelectricity in activating PMS remains unclear, and the crucial effect of spontaneous polarization is largely overlooked. This study elucidates the highly efficient capability of ferroelectric Bi 2 Fe 4 O 9 to activate PMS from the perspective of ferrocatalysis. Through experimental and theoretical analysis, it is proposed that the intrinsic ferrocatalytic activity is attributed to the spontaneous polarization that promotes the PMS adsorption process and accelerates the electron transfer. Bi 2 O 2 and FeO 6 surfaces of Bi 2 Fe 4 O 9 accumulate charge because of spontaneous polarization and elongate the O-O bond of PMS. The interfacial electron transfer between Bi 2 Fe 4 O 9 and PMS results in the generation of •OH and •SO 4 - for rapidly removing organic contaminants. This study presents atomic-scale insight into possible active sites and mechanisms of ferrocatalytic PMS activation, which may enlighten the exploitation of more effective ferroelectric materials for water treatment.