Enhanced electrocatalytic activity of palladium electrocatalysts supported on corncob biochar for ethanol oxidation reaction in alkaline medium.

In this study, palladium particles supported on carbon black (Vulcan XC-72) (Pd/C) and corncob biochar (Pd/CB800, Pd/CB900, and Pd/CB1000) were successfully synthesized using borohydride reduction. The biochar support was obtained from corncob waste via pyrolysis from 800 to 1000°C. Scanning electron microscopy with energy dispersive x-ray (SEM–EDX) revealed successful deposition of Pd metal particles on the carbon support materials. X-ray diffraction (XRD) analysis confirmed the crystalline structures of Pd, and the crystallite size was found to be smallest in Pd/CB900. The electrocatalytic activity of the Pd electrocatalyst composites towards ethanol oxidation reaction (EOR) in an alkaline medium was investigated using cyclic voltammetry (CV). CV analysis has shown that Pd/CB900 gave the least positive onset potential (Eonset = −0.587 ± 0.0065 V), highest electrochemically active surface area (EASA = 31.51 ± 2.24 m²·g−1), and highest anodic peak current density (If = 20.77 mA·cm−2) compared with Pd/CB800, Pd/CB1000, and Pd/C. Furthermore, the Tafel plot and chronoamperometry have shown that Pd/CB900 exhibited faster kinetics (Tafel slope = 297.6 ± 4.62 mV·dec−1) and durability (% current retention = 50.64 ± 2.99%) than Pd/C towards EOR in an alkaline medium. This study highlights the simple and straightforward synthesis of the anode electrocatalyst material for direct ethanol fuel cell application. [ABSTRACT FROM AUTHOR]