Efficient degradation of chlorinated phenolic compounds by Fe@Cu materials with enhanced oxygen reduction reaction

Abstract

Purification of wastewater that contains residual chlorinated phenolic compounds is important for water conservation. Fe@Cu bimetallic materials have the capability of degrading chlorinated phenolic pollutants, but the processes of electron transfer and active species generation have not been verified directly. In this work, the Fe@Cu bimetallic material, of which copper exhibits a special surface, obtained by a facile displacement reaction, was applied for 2,4-dichlorophenol (2,4-DCP) degradation. The degradation efficiency of 2,4-DCP, which is highly related to H2O2 generation and •OH production, can reach 100% at 30 min with an Fe@Cu dosage of 2 g/L in ambient atmosphere. The porous shell structure of Fe@Cu provides convenient channels for iron ion release and electron transport and transformation. According to DFT (density functional theory) calculations, Cu2O (111) on the surface of particles and Cu (111) with Fe doping possess higher selectivity and catalytic activity for H2O2 in situ generation through the 2e− oxygen reduction reaction (ORR) than Cu (111). The ⋅OH, which was the following product of *OOH and H2O2, was a strategic radical for 2,4-DCP degradation. The coexistence of •OH and •H in the Fe-Cu degradation system was directly proven. The intermediate products of 2,4-DCP degradation were identified, and the degradation intermediates revealed that the degradation function for 2,4-DCP mainly resulted from the synergistic action of ⋅H and ⋅OH. The highly efficient self-catalyst Fe@Cu can be a promising material for chlorinated phenolic compound removal in wastewater purification.