Natural illite-based ultrafine cobalt oxide with abundant oxygen-vacancies for highly efficient Fenton-like catalysis

[Display omitted] •Oxygen-vacancy-rich Co3O4/illite can activate peroxymonosulfate (PMS) efficiently.•Modulating crystallization of Co3O4 by illite resulted in rich oxygen vacancies.•Theoretical calculations were employed to elucidate catalytic mechanism for PMS.•Rich oxygen vacancies accelerated electron-transfer and reduced adsorption energy.•SO4-•, OH and 1O2 were generated and functioned in Co3O4/illite/PMS system. Natural illite microsheets were firstly utilized to induce oxygen vacancies into ultrafine cobalt oxide (Co3O4) for highly efficient Fenton-like catalysis via activation of peroxymonosulfate (PMS). The results indicated that presence of illite microsheets regulated multi-directional crystallization of Co3O4 nanospheres and resulted in reduced grain size and crystallinity. The smaller grain size provided more reactive edge sites for PMS catalysis. The numerous indistinct lattice boundaries caused by reduced crystallinity created abundant oxygen vacancies. Density functional theory (DFT) calculations illustrated that presence of oxygen vacancies significantly reduced adsorption energy and accelerated electron transfer, which further faciliated PMS activation. The oxygen vacancy-rich Co3O4/illite exhibited superior catalytic efficiency in real water matrix. Apart from sulfate and hydroxyl radicals, singlet oxygen generated from oxygen vacancy-based reaction pathway also played a significant role in atrazine degradation. This strategy provided a new insight for future designing of natural mineral-based catalysts for efficient wastewater treatment via Fenton-like process.