Electrically Enhanced Catalytic Activity of Gold Nanocoatings in Carbon Monoxide Oxidation

Measurements are reported of the increase in catalytic CO oxidation rate on gold nanocoatings obtained by applying a positive or negative electrical voltage of variable magnitude to a coating. In experiments on an initial mixture of 1.8% СО + 10.2% О 2 + Ar and a coating with a starting particle size of 0.2 to 3 nm, conducted at 430°C and atmospheric pressure, the extent of the CO oxidation rate enhancement caused by a stepwise increase in the applied positive voltage initially amounts to 28% at +10 V and then declines to 20% at +30 V. Applying a negative voltage has a weaker effect: after an initial increase by 12% at –10 V, the extent of the enhancement of the CO oxidation rate declines to 7% at –30 V. Quantum chemical calculations are performed to determine the heats of association for CO and O 2 with the simplest electrically neutral or electrically charged Au 3 cluster, as well as the heats of the reaction for Au 3 CO + O → Au 3 CO 2 and Au 3 CO 2 → Au 3 + CO 2 involving differently charged Au3 complexes. Based on the calculated results, an explanation is proposed for the increased catalytic CO oxidation rate on electrically charged gold nanocoatings.