Electrocatalytic activity of Vulcan-XC-72 supported Pd, Rh and PdxRhy toward HOR and ORR
Carbon-supported (Vulcan XC-72) Pd, Rh, and PdxRhy (20 wt%, x:y = 1:1, 3:1, 1:3) electrocatalysts are prepared according a modified pulse-microwave assisted polyol synthesis method and their electrocatalytic activity toward hydrogen electrooxidation (HOR) and oxygen reduction (ORR) reactions is investigated. The as-prepared electrocatalysts are physicochemically characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Their electrochemical characterization is carried out by the aid of cyclic voltammetry (CV), rotating disk electrode (ROE) and chronoamperometry (CA) techniques. It is found that among the as-prepared catalysts, PdRh3 exhibits the highest HOR (i(k) = 7.6 mA cm(-2)) and ORR (i(k) = 5.20 mA cm(-2)) electrocatalytic activity. It is also found that the addition even of small amount of Rh (Pd3Rh-2.7 mu g cm(-2)) enhances both Pd's HOR and ORR electrocatalytic activity by 33% and by 53%, respectively. For the as prepared electrocatalysts, the HOR activity order, in terms of kinetic current density, is found to be as follows: PdRh3 approximate to PdRh > Rh > Pd3Rh > Pd, while a similar trend was found for ORR activity: PdRh3 > PdRh > Rh > Pd3Rh > Pd. (C) 2015 Elsevier B.V. All rights reserved.