Effect of Ru Dopant Amount on the Electrocatalytic Capability of Ti/SnO2-Sb-Gd-Ru Electrodes in the Phenol Oxidation
The electrodes were synthesized using the Pechini method  and calcined at 600° C. The relationship molar acid ethylene glycol/citric/metals was 3/14/1, respectively. The molar relations of Sn/Sb(5%) and Sn/Gd(1%) were constants and Ru amount was variable: Sn/Ru(0, 0.25, 0.5, 0.75%). The obtained electrodes were characterized by X-ray, microscopy electron scanning (SEM), photoelectron spectroscopy (XPS). The electrochemical characterization of electrodes was carried out by cyclic voltammetry, determination of Tafel slope with respect to the oxygen evolution reaction, the roughness factor and accelerated life tests. The electrocatalytic activity of electrodes was evaluated with respect to the electrooxidation of a phenol solution (100 ppm) to constant current (60 mA). The phenol solution was analyzed during the electrolysis by UV-Vis spectroscopy, liquid chromatography high efficiency (HPLC) and total organic carbon (TOC).
The results indicate that the incorporation of Ru in the system Ti/SnO2-Sb-Gd, induces changes in crystallinity and morphology of the material, also modifies the antimony content and the oxygen content in the SnO2 network on the surface of the film. The percentages of Sb+5 were much higher on the surface for Sn/Ru(0.25%) in comparison to others electrode materials. The presence of Ru slightly modifies the potential onset of the oxygen evolution reaction (OER). Therefore, with regard to the system Ti/SnO2-Sb(5%)-Gd(1%), the addition of small amounts of Ru does not produce a substantial effect on variation in phenol degradation and TOC removal as shown in Fig. 1, in addition, the presence of Ru increases the life time of the electrodes.
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