Carbon Monoxide Oxidation over rGO-Mediated Gold/Cobalt Oxide Catalysts with Strong Metal-Support Interaction.

The strong interaction between Au nanoparticles and support (Au-metal oxide interface) usually governs the performance of a supported Au catalyst in heterogeneous catalysis. In this study, a series of Au/reduced graphene oxide (rGO)/three-dimensionally ordered macroporous (3DOM) Co3O4 catalysts with similar textural properties were prepared using the poly(methyl methacrylate)-templating and poly(vinyl alcohol)-protected reduction strategies. It was found that introducing reduced graphene oxide (rGO) as an electron-transfer bridge between Au and 3DOM Co3O4 could significantly strengthen the strong metal-support interaction (SMSI), thus enhancing the catalytic activity for CO oxidation. Among all of the catalysts, 1.86 wt % Au/2 wt % rGO/3DOM Co3O4 (1.86Au/2rGO/3DOM Co3O4) showed the highest catalytic activity: the CO reaction rate at 40 °C (432.8 μmol/(gAu s)) was 2 times higher than that (208.2 μmol/(gAu s)) over 1.87Au/3DOM Co3O4. The introduction of rGO could improve the activation of oxygen molecules and hence increase the low-temperature catalytic activity. The strategy for strengthening the SMSI via rGO mediation would guide the designing of highly efficient supported metal catalysts for low-temperature oxidation of CO.