Pronounced effect of yttrium oxide on the activity of Pd/rGO electrocatalyst for formic acid oxidation reaction

Abstract

A highly efficient and stable electrocatalyst comprised of yttrium oxide (Y2O3) and palladium nanoparticles has been synthesized via a sodium borohydride reduction approach. The molar ratio of Pd and Y was varied to fabricate various electrocatalysts and the oxidation reaction of formic acid was checked. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD) are used to characterize the synthesized catalysts. Among the synthesized catalysts (PdyYx/rGO), the optimized catalyst i.e., Pd6Y4/rGO exhibits the highest current density (106 mA cm−2) and lowest onset potential compared to Pd/rGO (28.1 mA cm−2) and benchmark Pd/C (21.7 mA cm−2). The addition of Y2O3 to the rGO surface results in electrochemically active sites due to the improved geometric structure and bifunctional components. The electrochemically active surface area 119.4 m2 g−1 is calculated for Pd6Y4/rGO, which is ∼1.108, ∼1.24, ∼1.47 and 1.55 times larger than Pd4Y6/rGO, Pd2Y8/rGO, Pd/C and Pd/rGO, respectively. The redesigned Pd structures on Y2O3-promoted rGO give exceptional stability and enhanced resistance to CO poisoning. The outstanding electrocatalytic performance of the Pd6Y4/rGO electrocatalyst is ascribed to uniform dispersion of small size palladium nanoparticles which is possibly due to the presence of yttrium oxide.