Pd/c-PANI electrocatalysts for direct borohydride fuel cells

Abstract

Carbon-supported palladium nanoparticle electrocatalysts were prepared using two different carbon supports, commercial Vulcan® XC72 (Pd/Vul) and synthesized carbonized nanostructured polyaniline doped with 3,5-dinitrosalicylic acid (Pd/c-PANI), and using two different synthesis procedures. Morphology and Pd content for each of the four electrocatalysts were determined using transmission electron microscopy and thermogravimetric analysis, respectively. The electrocatalysts were further analyzed electrochemically using cyclic voltammetry and linear scan voltammetry with a rotating ring–disc electrode, as well as chronoamperometry, considering their activity in direct borohydride/peroxide fuel cells, i.e., for the borohydride oxidation reaction (BOR) in alkaline media as well as for the hydrogen peroxide reduction reaction (HPRR) in acidic media. The number of electrons exchanged in BOR varied between 2.4 and 4.8, while unique n value of 2 was evidenced in HPRR. Activation energies for BOR at studied materials were in the 10.3–26.2kJmol−1 range and for HPRR in the 31.7–48.3kJmol−1 range.