Boosting the singlet oxygen production from H 2 O 2 activation with highly dispersed Co-N-graphene for pollutant removal.

Singlet oxygen ( 1 O 2 ) is a promising reactive species for the selective degradation of organic pollutants. However, it is difficult to generate 1 O 2 from H 2 O 2 activation with high efficiency and selectivity. In this work, a graphene-supported highly dispersed cobalt catalyst with abundant Co-N x active sites (Co-N-graphene) was synthesized for activating H 2 O 2 . The Co-N-graphene catalyzed H 2 O 2 reaction system selectively catalyzed 1 O 2 production associated with the superoxide radical (O 2 ˙ - ) 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 -1 (g L catalyst -1 ) -1 under optimal reaction conditions ( C H 2 O 2 = 400 mM, initial pH = 9). Furthermore, this Co-N-graphene catalyst enabled strong synergy with HCO 3 - in accelerating MB degradation, whereas the scavenger experiment implied that the synergy herein differed significantly from the current Co 2+ -HCO 3 - reaction system, in which contribution of O 2 ˙ - was only validated with a Co-N-graphene catalyst. Therefore, this work developed a novel catalyst for boosting 1 O 2 production from H 2 O 2 activation and will extend the inventory of catalysts for advanced oxidation processes.