In this work, three Co3O4 nanostructures
with different morphologies (cubes, rods, and sheets) were synthesized
using a hydrothermal method and tested for the CO2 hydrogenation
reaction. The physicochemical properties of the structured Co3O4 were well characterized by X-ray diffraction
(XRD), Raman spectroscopy, field-emission scanning electron microscopy
(FESEM), transmission electron microscopy (TEM), high-resolution transmission
electron microscopy (HRTEM), hydrogen temperature-programmed reduction
(H2-TPR), and X-ray photoelectron spectroscopy (XPS) techniques.
Based on the characterization, cube, rod, and sheet Co3O4 nanostructures were found to expose the (100), (110),
and (112) planes, respectively. The effect of cobalt oxide morphologies
with different exposed surfaces on the activity and selectivity toward
CO2 hydrogenation reaction in a plug-flow reactor operated
between 200 and 400 °C under atmospheric pressure conditions
was explored. The results establish a correlation of the catalytic
activity with morphological structures in the order rods > sheets
> cubes. H2-TPR and XPS studies demonstrated that the
high
reducibility of Co3O4 rod makes it an excellent
catalyst for CO2 hydrogenation.