Ultrafine ZnCoO QD-incorporated carbon nitride mediated peroxymonosulfate activation for norfloxacin oxidation: performance, mechanisms and pathways.

Recently, peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) are being actively investigated as a potential technology for water decontamination and many efforts have been made to improve the activation efficiency of PMS. Herein, a 0D metal oxide quantum dot (QD)-2D ultrathin g-CN nanosheet (ZnCoO/g-CN) hybrid was facilely fabricated through a one-pot hydrothermal process and used as an efficient PMS activator. Benefiting from the restricted growth effect of the g-CN support, ultrafine ZnCoO QDs (∼3-5 nm) are uniformly and stably anchored onto the surface. The ultrafine ZnCoO possesses high specific surface areas and shortened mass/electron transport route so that the internal static electric field () formed in the interface between p-type ZnCoO and the n-type g-CN semiconductor could speed up the electron transfer during the catalytic reaction. This thereby induces the high-efficiency PMS activation for rapid organic pollutant removal. As expected, the ZnCoO/g-CN hybrid catalysts significantly outperformed individual ZnCoO and g-CN in catalytic oxidative degradation of norfloxacin (NOR) in the presence of PMS (95.3% removal of 20 mg L of NOR in 120 min). Furthermore, the ZnCoO/g-CN-mediated PMS activation system was systematically studied in terms of the identification of reactive radicals, the impact of control factors, and the recyclability of the catalyst. The results of this study demonstrated the great potential of a built-in electric field-driven catalyst as a novel PMS activator for the remediation of contaminated water.