One-pot synthesis of a novel hierarchical Co(II)-doped TiO2 nanostructure: Toward highly active and durable catalyst of peroxymonosulfate activation for degradation of antibiotics and other organic pollutants

A novel hierarchical Co(II)-doped TiO2 (hCTO) nanostructure with abundant and easily accessible active sites was fabricated through a simple one-pot hydrothermal route and innovatively studied as the potential alternative to conventional cobalt-based catalysts for peroxymonosulfate (PMS) activation. Detailed characterization indicated that hCTO was well organized by two-dimensional porous crystalline nanosheets, exhibiting a corollalike morphology with large surface area (131.2 m(2) g(-1)) and highly open structure. More interestingly, the Co(II) ions were found to be preferentially doped into TiO2 surface lattice, which led to a high density of surface active sites. Due to the combination of multiple unique characteristics, hCTO displayed an excellent catalytic efficiency in PMS solution, enabling almost complete removal of ofloxacin in a short time period, with a rate constant (1.22 min(-1)) significantly higher than that (0.099 min(-1)) of Co3O4. Through identification of active radicals and intermediate products in the degradation process, the catalytic mechanism and the potential degradation pathway were proposed. Moreover, hCTO was demonstrated to be highly efficient in activating PMS for degradation of other recalcitrant organic pollutants including norfloxacin, rhodamine B, and methyl orange. Besides, the hCTO exhibited excellent catalytic reusability, without obvious activity loss after reuse several times. This work provides a promising approach on the rational design of cost-effective, highly active, and durable PMS activators for environmental remediation.