Hierarchical Pt/MnO₂–Ni(OH)₂ Hybrid Nanoflakes with Enhanced Room-Temperature Formaldehyde\nOxidation Activity

Abstract

Nickel\nfoam (NF)-supported Pt/MnNi@NF catalyst was prepared via\nin situ hydrothermal growth of manganese dioxide–nickel­(II)\nhydroxide (MnO₂–Ni­(OH)₂) hierarchical\nnanosheets and subsequent impregnation–borohydride reduction\nto deposit well-dispersed platinum (Pt) nanoparticles (NPs). The free-standing\ncomposite catalyst exhibited improved performance for room-temperature\nformaldehyde (HCHO) oxidation due to synergistic effect of Pt, MnNi\nnanosheets, and the NF substrate, considering the lack of HCHO oxidation\nactivity in the absence of Pt or MnO₂–Ni­(OH)₂ and low activity of powder-like Pt/MnO₂–Ni­(OH)₂ in the absence of NF. Surface hydroxyl (OH) groups of MnO₂ and Ni­(OH)₂ were helpful for the adsorption of\nHCHO, while Pt NPs facilitated the formation of active oxygen species.\nBesides, oxygen vacancies on the surface of MnO₂ were beneficial\nfor the migration of active oxygen species. The NF not only served\nas a substrate but also contributed to the formation of thinner nanosheets\nwith larger lateral size and smaller grain size, thus exposing more\nactive sites and improving the homogeneous dispersion of Pt nanoparticles.\nTherefore, this NF-supported free-standing composite catalyst holds\ngreat promise for application in indoor HCHO abatement.