Promoting effect of polyaniline on Pd catalysts for the formic acid electrooxidation reaction

Composition dependent activity of PdAgNi alloy catalysts for formic acid electrooxidation

In the present study, the carbon supported Pd, PdAg and PdAgNi (Pd/C, PdAg/C and PdAgNi/C) electrocatalysts are prepared via NaBH₄ reduction method at varying molar atomic ratio for formic acid electrooxidation. These as-prepared electrocatalysts are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma mass spectrometry (ICP-MS), N₂ adsorption-desorption, and X-ray electron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and lineer sweep voltammetry (LSV). While Pd₅₀Ag₅₀/C exhibits the highest catalytic activity among the bimetallic electrocatalyst, it is observed that Pd₇₀Ag₂₀Ni₁₀/C electrocatalysts have the best performance among the all electrocatalysts. Its maximum current density is about 1.92 times higher than that of Pd/C (0.675 mA cm^-2). Also, electrochemical impedance spectroscopy (EIS), chronoamperometry (CA) and lineer sweep voltammetry (LSV) results are in a good agreement with CV results in terms of stability and electrocatalytic activity of Pd₅₀Ag₅₀/C and Pd₇₀Ag₂₀Ni₁₀/C. The Pd₇₀Ag₂₀Ni₁₀/C catalyst is believed to be a promising anode catalyst for the direct formic acid fuel cell.