Atomically Dispersed Cobalt Sites on Graphene as Efficient Periodate Activators for Selective Organic Pollutant Degradation
Yangke Long, Jian Dai, Shiyin Zhao, Yiping Su, Zhongying Wang, Zuotai Zhang
Abstract
Pollutant degradation via periodate (IO 4 – )-based advanced oxidation processes (AOPs) provides an economical, energy-efficient way for sustainable pollution control. Although single-atomic metal activation (SMA) can be exploited to optimize the pollution degradation process and understand the associated mechanisms governing IO 4 – -based AOPs, studies on this topic are rare. Herein, we demonstrated the first instance of using SMA for IO 4 – analysis by employing atomically dispersed Co active sites supported by N-doped graphene (N-rGO-CoSA) activators. N-rGO-CoSA efficiently activated IO 4 – for organic pollutant degradation over a wide pH range without producing radical species. The IO 4 – species underwent stoichiometric decomposition to generate the iodate (IO 3 – ) species. Whereas Co 2+ and Co 3 O 4 could not drive IO 4 – activation; the Co–N coordination sites exhibited high activation efficiency. The conductive graphene matrix reduced the contaminants/electron transport distance/resistance for these oxidation reactions and boosted the activation capacity by working in conjunction with metal centers. The N-rGO-CoSA/IO 4 – system exhibited a substrate-dependent reactivity that was not caused by iodyl (IO 3 · ) radicals. Electrochemical experiments demonstrated that the N-rGO-CoSA/IO 4 – system decomposed organic pollutants via electron-transfer-mediated nonradical processes, where N-rGO-CoSA/periodate* metastable complexes were the predominant oxidants, thereby opening a new avenue for designing efficient IO 4 – activators for the selective oxidation of organic pollutants.