A series of ordered mesoporous carbon (OMC)-supported Au catalysts were successfully prepared by nano-replication, followed by colloidal gold deposition method. Structural analysis showed that the mesopore sizes of the catalysts can be tuned controllably in the range of 3.2–7.6 nm by adjusting the dosage of boric acid used to prepare the carbon supports. TEM observations revealed that the Au nanoparticles were dispersed uniformly in the mesopore channels of the carbon supports. These Au/OMC catalysts were tested for the aerobic oxidation of glucose to produce gluconic acid at 40 °C and pH 9. As demonstrated by the structural analysis and reaction results, the activities of these catalysts were closely related to their mesopore sizes. The catalyst with a mesopore size of 5.4 nm exhibited a superior catalytic activity with a TOF of 4.308 molglucose molAu−1 s−1 to the catalysts reported previously by other researchers. This high activity was mainly ascribed to its unique structure, consisting of 5.4 nm mesopore channels incorporated with 3.3 nm Au nanoparticles, which facilitates contact between glucose molecules and Au nanoparticles. Besides, the abundant active oxygen species existing on this catalyst surface also promote glucose oxidation.

A series of Au-Cu/Co3O4 catalysts with different mass fractions of Cu were synthesized by a two-step method that consists of depositing gold and copper onto a Co3O4 support, which was synthesized by coprecipitation. The effect of copper on the catalytic activity of Au-Cu/Co3O4 was evaluated for the complete oxidation of ethylene at different temperatures and the prepared catalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), H-2 temperature-programmed reduction (H-2-TPR), and O-2 temperature-programmed desorption (O-2-TPD). The results show that Au-Cu/Co3O4 bimetal catalysts exhibit higher catalytic activities than the Au/Co3O4 catalyst. At a gold loading amount of 4% (w, mass fraction) the AuCu3/Co3O4 catalyst gives higher catalytic activity compared to catalysts AuCu/Co3O4 and Au3Cu/Co3O4. Ethylene conversion was 15.3% for AuCu3/Co3O4 even at 0 degrees C whereas at 120 degrees C the full conversion of ethylene was obtained. The results of XRD and HRTEM indicate the formation of an Au-Cu alloy in AuCu3/Co3O4. However, we have found that the majority of Cu is present in the form of Cu2O in Au3Cu/Co3O4. The interaction between Au and Cu on the surface of the catalysts decreases the particle size of the gold and, therefore, it is much easier to activate ethylene. H-2-TPR and O-2-TPD results show that the high reduction ability and the high intensity of surface oxygen active species contribute to the excellent catalytic activity of the AuCu3/Co3O4 catalyst.

Formaldehyde is regarded as the major indoor pollutant emitted from widely used building and decorative materials in airtight buildings, which should be eliminated under indoor environmental conditions. We report here catalytic oxidation process of formaldehyde over mesoporous Co3O4, Co3O4-CeO2, Au/Co3O4, and Au/Co3O4-CeO2 catalysts and their excellent catalytic performances at room temperature. These catalysts were prepared by a "nanocasting" method with the mesostructure generated from SBA-15 silica with 2D structure. The adsorbed surface species in the formaldehyde oxidation process are analyzed, and some key steps in the oxidation pathway, active sites, and intermediate species are proposed. Among the detected species, some kinds of formate species formed on the catalysts were indentified as intermediates, which further transformed into bicarbonate or carbonate and which decomposed to carbon dioxide. The role of the mesoporous Co3O4 and the gold nanoparticles in the mechanism are also revealed.

Au/Co3O4 catalysts with different morphologies (nanorods, nanopolyhedra and nanocubes) were successfully synthesized and evaluated for ethylene complete oxidation. We found that support morphology has a significant effect on catalytic activity, which is related to the exposed planes of different morphological Co3O4. HRTEM revealed the Co3O4-nanorods predominantly exposes {110} planes, while the dominant exposed planes of Co3O4-nanopolyhedra and -nanocubes are {011} and {001} planes, respectively. Compared with {011} and {001} planes, {110} planes exhibit the maximum amount of oxygen vacancies, which play a major role in ethylene oxidation. Therefore, Au/Co3O4-nanorods exhibits extraordinary catalytic activity, yielding 93.7% ethylene conversion at 0°C.