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

A highly efficient and stable electrocatalyst comprised of yttrium oxide (Y 2 O 3 ) 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 (Pd y Y x /rGO), the optimized catalyst i.e. , Pd 6 Y 4 /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 Y 2 O 3 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 m 2 g -1 is calculated for Pd 6 Y 4 /rGO, which is ∼1.108, ∼1.24, ∼1.47 and 1.55 times larger than Pd 4 Y 6 /rGO, Pd 2 Y 8 /rGO, Pd/C and Pd/rGO, respectively. The redesigned Pd structures on Y 2 O 3 -promoted rGO give exceptional stability and enhanced resistance to CO poisoning. The outstanding electrocatalytic performance of the Pd 6 Y 4 /rGO electrocatalyst is ascribed to uniform dispersion of small size palladium nanoparticles which is possibly due to the presence of yttrium oxide.