Synthesis of cellular-like Co3O4 nanocrystals with controlled structural, electronic and catalytic properties

Abstract

This work reports on the preparation of cellular-like Co3O4 nanocrystals with tailored physical properties via a seeded method by high temperature disposal. By increasing the disposal temperature, Co(OH)2 seeds can be efficiently transformed to Co3O4 nanocrystals. Systematic sample characterization using combined techniques of X-ray diffraction, scan electron microscope, Fourier transformed infrared spectra, UV–visible diffuse reflectance spectra, Barrett–Emmett–Teller technique and XPS spectra indicates that Co3O4 nanocrystals showed a monotonically lattice expansion with particle size reduction, which can be well-defined as a function of particle sizes as well as valence state of cobalt ions. As the consequence of lattice expansion of Co3O4 nanocrystals, the ν1 and ν2 modes of Co3O4 in infrared spectra showed systematic red shift from 580, 669 to 568, 663cm−1, respectively. Co3O4 nanocrystals prepared at 300°C displayed highest catalytic property for HCHO conversion, which can be explained by the balance of surface absorbed OH groups, BET surface area and charge state of cobalt ions.