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.