Critical role of dissolved oxygen and iron–copper synergy in dual-metal/char catalyst systems

Abstract

Additional energy or oxidants are usually needed in advanced oxidation processes (AOPs) to achieve high reaction efficiency, which has emerged as a major hindrance to their application. Herein, a low-temperature (250 °C) iron–copper modified biochar (Fe/Cu-BC) was constructed to activate dissolved oxygen (DO) for efficient degradation of refractory organic pollutants without external energy and oxidants. The generation of reactive oxygen species (ROS) including O₂˙⁻, ·OH, and ¹O₂ were detected in the Fe/Cu-BC system. Metal shielding experiments were performed to distinguish the contribution of multiple components. The conversion of Cu species in Fe/Cu-BC dominated DO activation to produce ROS. More importantly, the synergistic catalysis of Fe and Cu was a crucial factor for activity enhancement, which improved the electron donor capacity of Cu and promoted the redox cycle of Fe. Fe/Cu-BC exhibited excellent performance over a wide pH range and with interference from various background substances in natural water bodies. Overall, this work proposes a valuable strategy for the degradation of refractory organic pollutants by metal–carbon hybrid materials without the addition of external energy and oxidants, and a new insight into the enhancement of DO activation by iron–copper synergy.