Electronic Modification Effects Induced by Fe in Pt-Ru-Fe Ternary Catalyst on the Electrooxidation of CO/H<sub>2</sub> and Methanol

Abstract

Electro-oxidation of CO/H₂ and methanol was performed over a carbon supported Pt-Ru-Fe ternary alloy catalyst prepared via the conventional NaBH₄ reduction method. Physicochemical and electrochemical measurements were used to elucidate the respective roles of Ru and Fe in the ternary catalyst, revealing synergistic effects in the Pt-Ru-Fe catalyst on the electro-oxidation of CO/H₂ and methanol. The methanol oxidation activity of Pt₃Ru₂Fe/C was ca. 2.5 times higher than that of PtRu/C at 0.45 V vs. RHE as a result of enhanced CO tolerance. The enhanced CO tolerance of the Pt-Ru-Fe ternary alloy catalysts was derived from the reaction between the high mobility, weakly adsorbed CO on the Pt site that was electronically modified by alloying with Fe and adsorbed water species on the Ru site. This combination of features produced an improvement in the electro-oxidation of CO/H₂ and methanol at lower potential. On the basis of the data, it was proposed that the addition of a water activator such as Ru is indispensible in the design of multicomponent alloy catalysts for methanol oxidation, and the additional effect derived from an electronic modifier is an important factor for improving the CO and methanol oxidation activity of the catalyst containing the water activator.