Avaliação da RRO utilizando carbono Printex 6L modificado com óxidos bimetálicos de Nióbio e Paládio

The objective of this study is the evaluation of the behavior of oxygen reduction reaction (ORR) when using carbon electrodes Printex 6L modified with bimetallic oxides of Niobium and Palladium. The ORR can occur by two reaction paths, and in one of them there is the reduction of O2 molecule via two electrons to formation of H2O2 and another in which the O2 is reduced via four electrons with subsequent formation of H2O. Measurements of x-ray fluorescence (FRX) (PANanalytical, Rh beam source of 30 eV) were made as characterization of the material formed, such that one can observe an increase in the signs of each metal in accordance with the material content. Linear scan voltammetry studies were performed in an acid medium (0.1 mol L-1 K2SO4) in order to check the response of the synthesized material for the production of H2O2 through the ORR, being used 5% content levels of the carbon matrix materials and a proportion between the metals, so the subscript number on metal abbreviation means the proportion of it in relation to the second metal (for example, 5% Nb75Pd25, means 75% of niobium for 25% of Palladium in 5% total carbon metal). The experiments were conducted in a Autolab 302N, with 5mV scanning speed s-1 and rotating ring-disk electrode of 900 rpm rotating through the porous microlayer technique. Using the equation of power efficiency for hydrogen peroxide [1] 78.6% values were obtained for carbon Printex 6 L and 87.7% for the catalyst containing 5% Nb95Pd05 and listen to the potential displacement of early reaction to more positive potentials. Using the average number of electrons involved in the reaction [2] 2.3 values were obtained electrons involved for both materials. Thus, it was concluded that there is a change in the way of reaction of the ORR when modification of carbon, and this change favors greater production of hydrogen peroxide.