Mesoporous reduction state cobalt species-doped silica nanospheres: An efficient Fenton-like catalyst for dual-pathway degradation of organic pollutants

Abstract

A novel heterogeneous Co-containing Fenton-like catalyst consisting of mesoporous reduction state cobalt (RSCo)-doped silica (SiO2) nanospheres (mp-RSCo-SiO2 NSs) was prepared by an enhanced hydrothermal process. The catalyst exhibited very high activity and stability for a series of refractory pollutant degradation in a very wide pH range of 3.1–10.9. The Fenton-like reaction rate constant of this Co-containing catalyst was approximately 290 times higher than that of Co3O4 for pollutant degradation under the neutral and mild conditions. Based on the characterization, the catalyst possessed a porous nanosphere morphology, and the reduction state cobalt species, including nano-zero-valent cobalt (nZVCo) and Co2+, were found to be generated in the SiO2 framework through forming CoOSi bonds. During the Fenton-like reaction, the electron donation effect of organic pollutants was successfully realized through the interaction of “Pollutants → Co2+/0-SiO2”. The obtained electrons from pollutants were transferred to the catalyst surface and captured by H2O2, resulting in the generation of hydroxyl radicals (OH). Therefore, a dual-pathway degradation of the pollutants was realized: (I) oxidation and degradation as the electron donors for the system and (II) attacking and destruction by OH radicals. This work provided a new perspective on the effective utilization of the electrons of pollutants and the improvement of Fenton reaction efficiency.