Tunable S doping from Co3O4 to Co9S8 for peroxymonosulfate activation: Distinguished Radical/Nonradical species and generation pathways

The introduction of non-metal heteroatoms is an effective way to improve the catalytic properties of heterogeneous catalysts to peroxymonosulfate. Unfortunately, the influence of foreign elements on the catalytic process has not been deeply revealed. Herein, we reported a series of Co9S8 nanorods catalysts from Co3O4 precursor with different S doping ratios. S doping effectively enhanced the catalytic properties, and the catalytic process gradually switched from non-radical (O-1(2)) into radical (SO4 center dot-) with the increase of S doping ratio. Moreover, quenching experiments, EPR, XPS, and radicals quantification indicated that the concentration of O-1(2) exhibited a linear relationship with Delta OL. Indicating that O-1(2) was derived from the reaction between PMS and OL. S doping also altered the valency of cobalt. In Co3O4/PMS, ROS was generated through Co3+/Co2+ catalytic circle. However, in Co9S8/PMS, Co3+/Co2+/Co-0 were all involved and accounted for the generation of ROS due to the low redox potential of S2-. Our work may provide some new clues and strategies for studying the influence of foreign elements on the catalytic process in PMS-based heterogeneous catalytic system.

Automated summary

The study introduced a series of Co9S8 nanorods catalysts with different S doping ratios to improve catalytic properties, revealing the mechanism of S doping on the catalytic process. The work may offer new insights into the influence of foreign elements on catalytic processes in PMS-based heterogeneous catalytic systems.