Pd-Co nanoparticles decorated on different carbon based substrates as electrocatalyst for O2 reduction reaction

In this study, a facile process for the synthesis of bimetallic Pd-Co nanotubes on multi walled carbon nanotubes (MWCNTs) and chemically reduced graphene oxide (rGO) is reported. The synthesized nanocatalysts are characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX). Catalysts are evaluated for the oxygen reduction reaction (ORR) in basic media. The electrocatalytic performance of Pd-Co supported on rGO and MWCNTs toward ORR is compared with bimetallic and single Pd nanoparticles decorated on Vulcan carbon (XC-72R) by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and rotating disk electrode (RDE) in 0.1 M NaOH solution. The specific electrochemical surface areas of Pd-Co supported on rGO is higher than the corresponding carbon supported Pd nanoparticles (222.09 vs. 41.57 m(2) g(-1), respectively). The RDE results confirm that the final product of the oxygen reduction is water and the proposed main path is direct 4 electron transfer process with smooth transfer kinetic rate on the Pd-Co/rGO in comparison to Pd-Co/C. Furthermore, the lower charge transfer resistance of the particles in ORR process for the Pd-Co/rGO compared to single Pd/C catalyst, indicating it could be excellent candidate for ORR in alkaline media. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.