Shape-Directed\nGrowth of Palladium Nanocubes over\nNitrogen-Doped Reduced Graphene Oxide: A Simple Approach for the Fabrication\nof an Efficient and Durable Electrocatalyst for Formic Acid and Methanol\nOxidation Reactions

Herein, we report a simple and highly reproducible synthetic\nstrategy\nfor the shape-directed growth of palladium (Pd) nanocubes supported\nover nitrogen-doped reduced graphene oxide (NrGO). Characterization\nof the Pd/NrGO composite by Fourier transform infrared (FTIR) spectroscopy,\nscanning electron microscopy (SEM), energy-dispersive X-ray analysis\n(EDXA), X-ray photoelectron spectroscopy (XPS), transmission electron\nmicroscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy\nsuggests that the composite has a uniform distribution of nanocube-shaped\nPd clusters (with an average size of 8.14 nm) firmly anchored to the\nNrGO matrix. Cyclic voltammetry (CV), chronoamperometry (CA), and\nelectrochemical impedance spectroscopy (EIS) were used to test the\nelectrocatalytic performance and electrochemical stability of the\nPd/NrGO composite toward the formic acid oxidation reaction (FAOR)\nand methanol oxidation reaction (MOR). The Pd/NrGO composite exhibits\na better peak current density of 2.6 mA/cm<sup>2</sup> (FAOR) and\n2.2 mA/cm<sup>2</sup> (MOR) as against commercial Pd/C (0.76 mA/cm<sup>2</sup> for the FAOR, 1.6 mA/cm<sup>2</sup> for the MOR) and Pt/C\n(0.63 mA/cm<sup>2</sup> for the FAOR, 1.5 mA/cm<sup>2</sup> for the\nMOR) with a much lower overpotential requirement for the onset of\nboth the FAOR and MOR. The presented results clearly suggest that\nthe electrochemical stability and electrocatalytic performance of\nthe Pd/NrGO composite crafted for the present work are sufficient\nto qualify it as a promising alternative of Pt-based anode materials\nfor commercially relevant DFAFCs and DMFCs.