Improved formic acid oxidation using electrodeposited Pd-Cd electrocatalysts in sulfuric acid solution

In the present research, nanostructured Pd-Cd alloy electrocatalysts with different compositions were produced using the electrodeposition process. The morphology of the samples was studied by scanning electron microscopy analysis. Also, the elemental composition of the samples was determined by energy-dispersive X-ray spectroscopy and elemental mapping tests. Tafel polarization and electrochemical impedance spectroscopy methods were employed to determine the electrochemical corrosion properties of the synthesized samples in a solution containing 0.5 M sulfuric acid and 0.1 M formic acid. The linear sweep voltammetry, cyclic voltammetry, and chronoamperometry techniques were also employed to evaluate the electrocatalytic activity of prepared samples toward the oxidation of formic acid. In this respect, the influence of some factors such as formic acid and sulfuric acid concentrations and also potential scan rate was investigated. Compared to the pure Pd sample, the Pd-Cd samples were more reactive for the oxidation of formic acid. Besides, the sample with a lower amount of Pd (Pd1.3Cd) demonstrated much higher electrocatalytic activity than the Pd7.1Cd and Pd2.1Cd samples. The observed high mass activity of 15.06 A mg(pd)(-1) for the Pd1.3Cd sample which is 21.1 times higher than Pd/C is an interesting result of this study. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.