Synergy between cobalt and nickel on NiCo2O4 nanosheets promotes peroxymonosulfate activation for efficient norfloxacin degradation

Developing an ultraefficient heterogeneous catalyst for peroxymonosulfate (PMS) activation at a wide pH range is a challenge. Herein, ultrathin NiCo2O4 nanosheets (NiCo2O4NS, ~1 nm), with the dominant exposure of (311) facet, was designed for PMS activation. The NiCo2O4NS/PMS system exhibited superior degradation of norfloxacin (NOR) over a wide pH range. The synergistic effects between Ni and Co were the dominant activation mechanism. Compared with Co3O4, NiCo2O4NS adsorb PMS through a unique “bridge” mode, where both Co and adjacent Ni interact with the same O atom in PMS, increasing the number of electron transfer for enhanced breakage of OO bond. NiCo2O4NS with high cycling stability, could reach 100% degradation of other typical pollutants, and showed higher degradation performance in actual wastewater. This work unveils the intrinsic origin of the superior activity of Co-Ni spinel oxides for PMS activation for the first time, and demonstrates its application potential for organic contaminants degradation.