Effect of NH<sub>4</sub><sup>+</sup> on the Electrocatalytic Performance of Carbon Supported Pd Catalyst for Formic Acid Oxidation

Abstract

We investigated the effect of HClO4, NH4ClO4, and NaClO4 electrolytes on the electrocatalytic performance of a Pd/C catalyst electrode for formic acid oxidation. The Pd/C catalyst was characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The performance of the Pd/C catalyst electrode during formic acid oxidation in different electrolytes was measured using electrochemical methods. We found that the electrocatalytic activity and stability of the Pd/C catalyst electrode for formic acid oxidation decreased in the following order: NH4ClO4 > NaClO4 > HClO4. The difference in pH between the different electrolytes was small because of the presence of formic acid. Therefore, the electrolyte pH has a small effect and the cations have a large effect. The better performance of the NaClO4 electrolyte compared to the HClO4 electrolyte is due to a pH effect. The better performance of the NH4ClO4 electrolyte compared to the NaClO4 electrolyte is due to NH4 decreasing the adsorption strength and amount of CO on the Pd/C catalyst. This finding has large significance for the increase in the performance of the direct formic acid fuel cell (DFAFC).