Pyrolyzed iron–nitrogen–carbon hybrids for efficient contaminant decomposition via periodate activation: Active site and degradation mechanism

The practical application of periodate-based advanced oxidation technologies (PI-AOTs) for wastewater treatment requires efficient and cost-effective activators. Pyrolyzed Fe–N/C materials are potential candidates, however, their actual active sites and activation mechanisms are yet to be fully understood. Herein, a series of Fe–N/C samples (denoted as Fe@NC- X ) with differing structures and iron components were delicately synthesized. Experimental studies on the structure–activity relationship and density functional theory (DFT) computations revealed that Fe–N x species serve as the dominant active site for periodate activation, while the inactive iron-based particles (i.e., Fe 0 and Fe 3 C) optimized the binding affinity of surrounding carbon layers with periodate, resulting in enhanced activity. In-depth exploration of the oxidative mechanism revealed that Fe@NC- X activated periodate through an electron transfer regime. Our results also showed that the optimal Fe@NC-0.2/periodate system was highly effective in catalyzing the oxidation of 4-CP, outperforming many reported activators. These findings provide an indispensable foundation for the rational development of advanced Fe–N/C activators and offer vital insights into the mechanism underlying pollutant destruction through PI-AOTs.