Photophysical and Photocatalytic Properties of Core-Ring Structured NiCo2O4 Nanoplatelets

Abstract

The innovative core-ring structured NiCo 2 O 4 nanoplatelets were found to be novel and promising photocatalysts. The physical and photophysical properties of the photocatalyst were characterized by SEM, TEM, XPS, UV−vis absorption, and photoluminescence, respectively. The core-ring NiCo 2 O 4 nanoplatelets were composed of much smaller nanocrystallines, with an average size of 80−150 nm, compared to the ordinary NiCo 2 O 4 prepared through a conventional hydroxide decomposition method. Moreover, the optical band gap energies of the core-ring NiCo 2 O 4 nanoplatelets were estimated to be 2.06 and 3.63 eV from the UV−vis absorption spectra. The core-ring structured NiCo 2 O 4 photocatalyst exhibited a much higher photocatalytic activity for the degradation of methylene blue than the ordinary NiCo 2 O 4 and TiO 2 under visible light irradiation (>420 nm). This enhanced photocatalytic activity of the core-ring NiCo 2 O 4 nanoplatelets was attributed to their higher optical absorption ability, smaller particle size, and more active internal electron transitions. On the basis of all the results, the band structure of the photocatalyst was discussed.