Solvothermal synthesis and gas-sensing performance of Co 3O 4 hollow nanospheres

Abstract

Co 3O 4 hollow nanospheres with a diameter of 200–300 nm were synthesized by a surfactant-assisted solvothermal method. X-ray diffraction and Raman spectrum measurements demonstrate that the products are pure face-centered cubic Co 3O 4. Transmission electron microscopy and selected area electron diffraction analyses reveal that the walls of Co 3O 4 hollow nanospheres have a uniform thickness of ∼40 nm and are constructed by an oriented aggregation of Co 3O 4 nanocrystals. The optical absorption properties of the Co 3O 4 hollow nanospheres were investigated by UV–vis spectroscopy and the results indicate that the Co 3O 4 hollow nanospheres are semiconducting with direct band gaps of 2.23, 1.25 and 1.00 eV. The gas-sensing performance of the as-prepared Co 3O 4 hollow nanospheres was investigated towards a series of typical organic solvents and fuels. The Co 3O 4 hollow nanospheres show good sensing performances towards toluene and acetone vapors with rapid response and high sensitivity at low operating temperature.