Boosting the singlet oxygen production from HO activation with highly dispersed Co-N-graphene for pollutant removal.

Singlet oxygen (O) is a promising reactive species for the selective degradation of organic pollutants. However, it is difficult to generate O from HO activation with high efficiency and selectivity. In this work, a graphene-supported highly dispersed cobalt catalyst with abundant Co-N active sites (Co-N-graphene) was synthesized for activating HO. The Co-N-graphene catalyzed HO reaction system selectively catalyzed O production associated with the superoxide radical (O˙) as the critical intermediate, as proven by scavenger experiments, electron spin resonance (ESR) spin trapping and a kinetic solvent isotope effect study. This resulted in excellent degradation efficiency towards the model organic pollutant methylene blue (MB), with an outstanding pseudo-first-order kinetic rate constant of 0.432 min (g L ) under optimal reaction conditions ( = 400 mM, initial pH = 9). Furthermore, this Co-N-graphene catalyst enabled strong synergy with HCO in accelerating MB degradation, whereas the scavenger experiment implied that the synergy herein differed significantly from the current Co-HCO reaction system, in which contribution of O˙ was only validated with a Co-N-graphene catalyst. Therefore, this work developed a novel catalyst for boosting O production from HO activation and will extend the inventory of catalysts for advanced oxidation processes.