Manipulating high-valent cobalt-oxo
[Co(IV)O]
species in
a catalytic system is pivotal; however, it is challenging due to the
inefficiency and unsustainability of Co(IV)O generation. In
this study, we fabricated macroscopic porous Co/N codoped carbon beads
(Co–NC) and identified Co(IV)O as the prominent species
in peroxymonosulfate (PMS) activation. Specifically, Co(IV)O
species on a Co–NC-900/PMS system was regarded as the crucial
driver of tetracycline (TC) removal (with a degradation efficiency
of 97.3% and an initial concentration of 20 mg L–1) through quenching experiments, methyl phenyl sulfoxide (PMSO) degradation,
and methyl phenyl sulfone (PMSO2) generation. Importantly,
Co–N
x
active sites are responsible
for the formation of Co(IV)O species, which contribute as
much as 98.33% to TC degradation based on the calculation of the steady-state
concentration. In addition, the relative contributions of Co(IV)O
toward various micropollutants are substrate-specific and related
to their ionization potential (IP). The practical application of Co–NC-900
was further evaluated in the continuous flow mode, and it showed excellent
durability and performance. Overall, we have aroused the importance
of Co(IV)O on micropollutants removal in heterogeneous systems
and provided an alternative macroscopic catalyst that can be potentially
exploited in real water decontamination scenarios.