Methanol resistant ruthenium electrocatalysts for oxygen reduction synthesized by pyrolysis of Ru_3(CO)_(12) in different atmospheres

摘要

Novel ruthenium electrocatalysts for the oxygen reduction reaction (ORR) were prepared by pyrolysis of Ru_3(CO)_(12) in three atmospheres: neutral (N_2), partially oxidative (air) and partially reductive (70:30 N_2/H_2), at temperatures in the 80-700℃ range. The materials were characterized by FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy. A thermogravimetric analysis of the Ru_3(CO)_(12) precursor in the three atmospheres was also performed. The electrocatalytic properties of the materials were evaluated by rotating disk electrode measurements in 0.5 mol L~(-1) H_2SO_4. The kinetic parameters, such as the Tafel slope, exchange current density and charge transfer coefficient, are reported. The catalysts prepared in N_2 and N_2/H_2, in general, show a higher performance than those synthesized in air. In the two nitrogen containing atmospheres, a pyrolysis temperature of 360 ℃ seems to lead to better electrocatalytic properties for the ORR. The new electrocatalysts are also tolerant to methanol concentrations as high as 2.0 mol L~(-1).