Electrical Stimulation of Catalytic Activity of Platinum Nanocoatings in CO oxidation

Abstract

An increase in the rate of catalytic CO oxidation for platinum nanocoatings was measured when the electrical stress of various polarity and value was applied to a coating from an external source. Under conditions of the experiment at 250°C, atmospheric pressure and the starting composition mixture of 4.8% CO + 10.2% O2 + Ar, applying the positive stress of +10 or +30 V on a coating leads to increase in the rate of CO oxidation by 18 or 54%, respectively. Applying the negative stress of –10 or –30 V leads to small acceleration in oxidation by 4 or 8%. It is shown that the effect of applied stress does not depend on particle size in a coating and grows linearly with stress. Quantum-chemical calculations of heats of association of CO and O2 with electrically neutral or electrically charged platinum cluster were performed. It was found that the creation of the positive charge on Pt2 leads to decrease in the heat of CO association by 6.4 kcal/mol and increase in the heat of O2 association by 4.7 kcal/mol, while the creation of the negative charge on Pt2 leads to a small effect of decrease in the heat of CO association by 3.0 kcal/mol and increase in the heat of O2 association by 4.2 kcal/mol. From the results, it is proposed to explain increase in the rate of catalytic CO oxidation on platinum electrically charged with the help of the external stress source.