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 (∼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.

Nanoporous gold (NPG) catalysts were made by free corrosion and the effect of alkali-treatment on NPG has been investigated for the oxidation of CO. After being immersed in alkaline (NaOH or ammonia) solutions, the catalytic activity could be promoted dramatically while used for the room temperature reaction, and this promotional effect could be adjusted by varying the pH values of the alkaline solutions or immersing time. The roles of the alkaline were to provide OH -anions to form Au-OHsites, which were the active sites to form hydroxyl carbonyl (Au-OCOH -) with CO and activated the oxygen with hydroxyl carbonyl. A probable reaction mechanism was proposed.