Synergistic Effect of Polyaniline-Modified Pd/C Catalysts on Formic Acid Oxidation in a Weak Acid Medium (NH4)2SO4

To avoid carbonation of small organic molecule oxidation in alkalines by using noble metals in acid, as well as to keep the proton transfer capability of polyaniline (PAn) in an acidic medium, we investigated formic acid oxidation on PAn-supported Pd catalysts in a weak acid solution of (NH4)2SO4. PAn was electrochemically polymerized on porous carbon electrodes (PCE) and glass carbon electrodes (GCE) to form electrodes PAn/PCE and PAn/GCE, on which Pd particles were deposited by electrochemical deposition. The properties of fabricated electrodes were examined electrochemically with the aid of a scanning electron microscope and a Fourier transform infrared spectroscope. Formic acid oxidation on the electrode Pd/PAn/PCE has been proven to undergo direct oxidation of weakly reactive or nonadsorbed intermediates to form CO2. The synergistic effect of Pd, PAn, and carbon powders was proposed to explain the enhanced oxidation of formic acid on the electrode Pd/PAn/PCE.