Precise Design and Construction of 3D Nanoflowers Hollow Spherical NiO@MnMO_x (M = Co, Cu, and Fe) Catalysts for Efficiently Catalytic Elimination of 1,2-Dichlorobenzene

In this work, a series of three-dimensional (3D) Ni-based catalysts with hollow spherical shell and nanoflowers structures were successfully synthesized by hydrothermal and interfacial reaction methods, including Ni/C–Ar@MnCo NPs, NiO@MnCo NPs, NiO@MnCu NPs, and NiO@MnFe NPs. The Ni-based catalysts exhibited outstanding catalytic performance for the catalytic oxidation removal of 1,2-dichlorobenzene (o-DCB). What was interesting was that the NiO@MnCoO_x catalyst derived from a NiO@MnCo NPs precursor exhibited a best catalytic performance with the temperature corresponding to 90% conversion (T₉₀) at 375 °C for the catalytic oxidation of (o-DCB). Through Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H₂-temperature programmed reduction (H₂-TPR), and temperature-programmed desorption of NH₃/O₂(NH₃/O₂-TPD) characterizations, it is found that NiO@MnCoO_x catalyst possessed large specific surface area, more surface Ni²⁺, Mn⁴⁺, and Co³⁺ species, rich reactive oxygen species, strong redox ability, and a large number of strong acid sites, which jointly promoted the conversion of o-DCB at lower temperatures. Furthermore, a possible catalytic mechanism relating to Langmuir–Hinshelwood (L–H) models was proposed based on the active oxygen source on account of XPS, O₂-TPD, and in situ DRIFTS measurements on catalytic performance. This strategy provides a new idea for the design of Ni-based composite catalysts and is of high importance for the design and synthesis of hollow nanoflowers.