NiCo2N nanosheets catalyzed peroxymonosulfate activation to generate 1O2 and SO4'- for efficient pollutant degradation: The role of nitrogen atoms

Advanced heterogeneous catalysts are essential for enhancing peroxymonosulfate (PMS) activation. Herein, a novel and highly highly-efficient PMS activation catalyst, NiCo2N nanosheets (NiCo2N NS), is reported. Owing to the strong electron transfer ability of Ni-N and Co-N, the NiCo2N NS/PMS system exhibit outstanding degradation performance and high cycling stability (100 % degradation after four cycles). The Co 3d orbital electrons in NiCo2N are closer to the to the Fermi level than that in NiCo2O4 NS, resulting in its higher chemical reactivity with PMS. When PMS is adsorbed onto Ni-N and Co-N sites through a "bridge" mode, the O-O bond is broken instantaneously to generate SO4'- and HO*. The formed HO* is then deprotonated to O*, followed by a reaction with another O* to generate 1O2. This study reports the first use of transition-metal nitride as a heterogeneous catalyst in PMS activation and provides insights into the key role of N atoms.