Insights into the stability of gold nanoparticles supported on metal oxides for the base-free oxidation of glucose to gluconic acid

Gold (Au) catalysts have been rarely investigated for the oxidation of glucose in the absence of a base. These conditions are critical, however, to enable the sequential one-pot combination of cellulose hydrolysis and glucose oxidation. Here we evaluate the catalytic performance and stability of Au nanoparticles supported on metal oxides for the oxidation of glucose to gluconic acid under unadjusted pH and acidic conditions. The study provides insights into the deactivation of the catalysts caused by leaching and hydrothermal sintering of Au nanoparticles, as well as by adsorption of reactive species. We found that lowering the surface density of Au on metal oxides decreases the sintering rate of the Au nanoparticles and hence enhances the stability and activity of the catalysts.