NiCo 2 O 4 hollow microsphere–mediated ultrafast peroxymonosulfate activation for dye degradation

Morphology and dispersity are key factors for activating peroxymonosulfate (PMS). In this study, we designed a recyclable open-type NiCo 2 O 4 hollow microsphere via a simple hydrothermal method with the assistance of an NH 3 vesicle. The physical structure and chemical properties were characterized using techniques such as scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), N 2 adsorption and X-ray photoelectron spectroscopy (XPS). The test results confirm that the inner and outer surfaces of open-type NiCo 2 O 4 hollow-sphere can be efficiently utilized because of the hole on the surface of the catalyst, which can minimize the diffusion resistance of the reactants and products. Under optimized conditions, the total organic carbon (TOC) removal efficiency of rhodamine B (RhB) can reach up to 80% in 40 min, which is almost 50% shorter than the reported values. The reactive radicals were identified and the proposed reaction mechanism was well described. Moreover, the disturbances of HCO 3 − , NO 3 − , Cl − and H 2 PO 4 − were further investigated. As a result, HCO 3 − and NO 3 − suppressed the reaction while Cl − and H 2 PO 4 − had a double effect on reaction.