RSC Adv. 2022 Jun 16;12(28):17864-17872. doi: 10.1039/d2ra02491h. eCollection 2022 Jun 14.
Singlet oxygen (1O2) is a promising reactive species for the selective degradation of organic pollutants. However, it is difficult to generate 1O2 from H2O2 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 H2O2. The Co-N-graphene catalyzed H2O2 reaction system selectively catalyzed 1O2 production associated with the superoxide radical (O2˙-) 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 Lcatalyst-1)-1 under optimal reaction conditions (C H2O2 = 400 mM, initial pH = 9). Furthermore, this Co-N-graphene catalyst enabled strong synergy with HCO3- in accelerating MB degradation, whereas the scavenger experiment implied that the synergy herein differed significantly from the current Co2+-HCO3- reaction system, in which contribution of O2˙- was only validated with a Co-N-graphene catalyst. Therefore, this work developed a novel catalyst for boosting 1O2 production from H2O2 activation and will extend the inventory of catalysts for advanced oxidation processes.