Interface-engineered cavity-structured cobalt oxide as a boosted activator for peroxymonosulfate to degrade environmental hormones in water: Structural defects and oxygen vacancies-induced enhancement

While heterogeneous cobalt (Co) catalysts are useful peroxymonosulfate (PMS) activators, the development of a heterogeneous Co-based catalyst with intriguing physicochemical properties and outstanding catalytic activities is still of great interest. Herein, a unique cavity-structured grassy-like cobalt oxide (Co₃O₄) (CGCO) is proposed and fabricated through two-step modifications of partial sculpting and calcination using Co-based metal organic framework (Co-MOF) as an initial precursor. The as-prepared CGCO exhibits a cavity structure covered by grassy-like outer shells, thus possessing special physicochemical properties and enriched oxygen vacancy. These features enable CGCO a much more advantageous activator than commercial Co₃O₄ for activating PMS, and would efficiently remove 100% of bisphenol A (BA) rapidly. The activation energy (E_a) of BA degradation by CGCO+PMS is only 31.2 kJ/mol, which is lower than the recently-reported values. The density function theory calculation is performed to investigate the degradation pathway, and the corresponding eco-toxicity is also studied to realize the environmental implication of BA by CGCO-activated PMS as the toxicities and environmental impact of BA are significantly reduced. This work provides valuable information in term of preparation strategy of cavity structured metal oxide materials, which should be propitious for the degradation of environmental hormones via advanced oxidation reactions.