The improved activity of Co₃O₄ nanorods using silver in the catalytic oxidation of toluene

Co₃O₄ nanorods with diameters of ~0.15 μm and lengths of ~1 μm were prepared using a hydrothermal method via the assembly of microcrystals and tested in the catalytic oxidation of toluene. The catalytic performance of Co₃O₄ nanorods was improved by the addition of Ag at various concentrations, and the 7% Ag/Co₃O₄ catalyst achieves a toluene conversion of 90% at 256 °C with a space velocity of 78,000 mL g^-1 h^-1, which is much lower than that of the pristine Co₃O₄ (269 °C). The addition of Ag promoted the activation of the surface oxygen species and the formation of more oxygen vacancies, improving the relative low-temperature reducibility of Co₃O₄, which is favorable for toluene oxidation. Moreover, the 7% Ag/Co₃O₄ catalyst showed an excellent stability for toluene oxidation at 250 and 260 °C for 50 h under the same conditions.