Co single-atom catalyst outperforms its homogeneous counterpart for peroxymonosulfate activation to achieve efficient and rapid removal of nitenpyram

Peroxymonosulfate (PMS) based advanced oxidation processes have shown great potential to remove refractory organic pollutants. Developing catalysts that can effectively activate PMS and rapidly degrade pollutant in complex water environment remains a challenge. This study focused on the development of heterogeneous catalyst with high activity comparable to its homogeneous counterpart. The cobalt nanocrystals and single cobalt atom was anchored on porous N-doped graphene fabricating Co-NC and Co SAC, respectively. The PMS activation performance by Co2+, Co-NC, and Co SAC was evaluated by nitenpyram (NPR) degradation. Co SAC/PMS was determined as the radical and nonradical hybrid system, exhibiting great interference capability (100 % degradation of nitenpyram within 15 min in tap water, groundwater, river water, and seawater), high stability (maintaining similar to 100 % NPR removal efficiency over a 10-hour operation period), and broad pH suitability (effective from pH 3.0 to 11.0). The identification of catalytic site and the oxidation mechanism of NPR were further elucidated through theoretical calculation, revealing the synergistic oxidation of O-1(2), (OH)-O-center dot, and SO4 center dot- for NPR degradation. The content of Co2+ in the used Co SAC increased while the content of Co3+ decreased, implying that the role of HSO5- acted as electron donors to transfer electrons to Co site, forming O-1(2). Results in this study provided practical application of PMS activation based on single-atom catalyst, which outperforms its homogeneous counterpart.