Methanol oxidation at carbon paste electrodes modified with (Pt-Ru)/carbon aerogels nanocomposites

Mesoporous carbon aerogels (CAs) impregnated with (Pt-Ru) nanoparticles were prepared, incorporated into carbon paste electrodes (CPEs) and investigated as electrocatalysts for CH3OH electro-oxidation. The sol-gel method, followed by supercritical drying with liquid CO2 and thermal pyrolysis in an inert atmosphere, was used to obtain high mesoporous CAs. (Pt-Ru)/CAs nanocomposites with various (Pt-Ru) loading were prepared by using Ru(AcAc)3 and H2PtCl6 as metal precursors and the impregnation method. The morpho-structural peculiarities of the so prepared (Pt-Ru)/CAs electrocatalysts were examined by using elemental analysis, N2 adsorption-desorption isotherms, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) and selected area electron diffraction (SAED). Cyclic voltammetry measurements, carried out at (Pt-Ru)/CA-CPEs incorporating nanocomposites with various Pt-Ru loading and different specific surface areas, showed that CA with the highest specific surface area (843 m2/g) and impregnated with 6% (w/w) (Pt-Ru) nanoparticles exhibit the best CH3OH electro-oxidation efficiency. The Michaelis-Menten formalism was used to describe the dependence of the oxidation peak current on the CH3OH concentration, allowing the estimation of the modified electrodes sensitivities. Thus, for (Pt-Ru, 10%)/CA535-CPE was observed the highest sensitivity (12.5 ± 0.8 mA/M) and, at the same time, the highest maximum current density ever reported (153.1 mA/cm2 for 2 M CH3OH and an applied potential of 600 mV vs. SHE).