Ordered Mesoporous Cobalt Containing Perovskite as a High-Performance Heterogeneous Catalyst in Activation of...

An ordered mesoporous perovskite, La₂CoMnO_6-δ (MLCMO), was synthesized for the first time using a facile method of evaporation-induced self-assembly. The N₂-sorption, scanning electron microscopy, and transmission electron microscopy measurements indicated that the optimized MLCMO possessed a high specific surface area (58.7 m²/g) and was uniformly mesoporous (11.6 nm). The MLCMO exhibited superior catalytic performance in peroxymonosulfate (PMS) activation for atrazine (ATZ) degradation. From a comparison view, the catalytic activity of the mesoporous MLCMO outperformed that of the bulk La₂CoMnO_6-δ (LCMO) and other common PMS activators, including α-MnO₂, Co₃O₄, and CoFe₂O₄. The mechanisms of PMS activation by the MLCMO were investigated by X-ray photoelectron spectroscopy, electron spin resonance, and quenching tests. SO₄^•-, ^•OH, ¹O₂, and O₂^•- were identified as main reactive oxygen species generated from PMS activation. The Co and Mn in MLCMO were the active sites responsible for active radical generation. The lattice oxygen reversible redox sites (O_L^-/O_L^2-), which were involved in the electron transfer of the Mn^III/Mn^IV cycle, were demonstrated as redox partners to the cation active sites. In addition, the SO₄^•-/^•OH radical conversion was promoted at pH 11, which accelerated the consumption of PMS and seriously inhibited the degradation of ATZ.