Aerobic oxidation of D-glucose on support-free nanoporous gold

Nanoporous gold (NPG) catalysts, made by dealloying Ag/Au alloys, were found to be novel unsupported Au nanocatalysts that exhibited effective catalytic activity and high selectivity (similar to 99%) for the aerobic oxidation Of D-glucose to D-gluconic acid under mild conditions. Systematic studies have been carried out to discuss this new catalytic system, including the activity dependence as functions of pH value, temperature and NPG ligament size, reaction active sites, and reaction kinetics. The possible contribution from the residual Ag atoms trapped in the NPG ligaments was also discussed, which turned out to be unfavorable for the glucose oxidation. The unexpected observation of the catalytic activity from NPG with a ligament size as large as 60 nm indicated that the low-coordinated surface Au atoms should be the reaction active sites for glucose oxidation.