Highly active carbon nanotube supported PdAu alloy catalysts for ethanol electrooxidation in alkaline environment

Abstract

At present, ethanol electrooxidation study is performed on CNT supported Pd and PdAu catalysts to investigate the effect of Au addition to Pd towards the ethanol electrooxidation activity. NaBH4 reduction method is employed for the synthesis of Pd/CNT, Pd90Au10/CNT, Pd90Au10/CNT, Pd70Au30/CNT, Pd50Au50/CNT, and Pd40Au60/CNT catalysts. These catalysts are characterized via advanced surface analytical techniques namely N2 adsortion-desoprtion measurements,X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). The characterization results revealed that Pd90Au10/CNT has 205.42 m2/g and 1.18 cm3/g BET surface area (m2/g) and pore volume (cm3/g), respectively. On the other hand, XRD and XPS results revealed that the electronic state of Pd90Au10/CNT catalyst changed by Au addition to Pd. TEM and HRTEM and elemental mapping results reveal that Pd and Au is homogeneously dispersed and alloying of Pd and Au is clearly observed, in agreement with the XRD and XPS results. Ethanol electrooxidation measurements in alkaline environment are performed by Cyclic Voltammetry (CV), Chronoamperometry (CA), Electrochemical impedance spectroscop (EIS) techniques. Pd90Au10/CNT displayed the highest specific and mass activity. The synergistic effect between Pd and Au at optimized metal ratio was utilized to obtain an improvement in specific activity. Furthermore, Pd90Au10/CNT showed the lowest charge transfer resistance (Rct) and a long term stability. As a result, it is clear that PdAu catalyst is a promising catalyst for Alkaline Direct Ethanol Fuel Cells.