Facile fabrication of cobalt doped manganese oxide with hierarchical porosity for peroxymonosulfate activation: Performance investigation, mechanistic insight to degrade organic pollutants in water and DFT study

An economical and environment-friendly material as a catalyst is highly desirable to activate peroxymonosulfate (PMS) into reactive oxygen species (ROS). Cobalt-doped dumbbell-shaped manganese oxide (CoX˗MnO x where X  = 1.0, 6.0, 12.0, 18.0, and 24.0 mM) was synthesized as a PMS-activator for degrading organic pollutants in wastewater. We have developed a green, facile, and low-temperature route without any organic solvents, and templates to synthesize Co-doped dumbbell-shaped MnO x with hierarchical porosity. It is the first-ever research to use these materials for peroxymonosulfate activation. The microstructure contained nanoparticles that self-assembled into a maze-like dumbbell-shaped mesostructure. Phenol degradations after 9 min of Co18-MnO x /PMS, MnO x /PMS, Co 3 O 4 /PMS, PMS, and adsorption were 100%, 27%, 33%, 17%, and 5%, respectively. The Co18-MnO x morphology, microstructure, textural properties, and catalytic efficiency were well-retained after recycling. Compared to SO 4 ·− and · OH, 1 O 2 and O 2 ·− were the dominant ROS. The balance among redox couples of different species (Co 2+ /Co 3+ , Mn 3+ /Mn 4+ , O 2− /O 2 ) and PMS decomposition enabled ROS production. The high catalytic activity was assigned to the Mn/Co synergism, hierarchical microstructure, and ROS. Furthermore, the DFT study investigated the difference between the activation mechanism of PMS (adsorption and electron transfer) on MnOx and Co-MnOx surfaces. Our research devised a facile procedure to synthesize other transition metals doped MnO x for advanced oxidation processes and multipurpose applications.