Macroporous Ni foam-supported Co3O4 nanobrush and nanomace hybrid arrays for high-efficiency CO oxidation.

Herein, we reported the synthesis of well-defined Co3O4 nanoarrays (NAs) supported on a monolithic three-dimensional macroporous nickel (Ni) foam substrate for use in high-efficiency CO oxidation. The monolithic Co3O4 NAs catalysts were obtained through a generic hydrothermal synthesis route with subsequent calcination. By controlling the reaction time, solvent polarity and deposition agent, these Co3O4 NAs catalysts exhibited various novel morphologies (single or hybrid arrays), whose physicochemical properties were further characterized by using several analytical techniques. Based on the catalytic and characterization analyses, it was found that the Co3O4 NAs-6 catalyst with nanobrush and nanomace arrays displayed enhanced catalytic activity for CO oxidation, achieving an efficient 100% CO oxidation conversion at a gas hourly space velocity (GHSV) 10,000hr-1 and 150°C with long-term stability. Compared with the other Co3O4 NAs catalysts, it had the highest abundance of surface-adsorbed oxygen species, excellent low-temperature reducibility and was rich in surface-active sites (Co3+/Co2+=1.26).