Preparation, Characterization And Electrochemical Performace Of Rthenium-titanium Composite Oxide And Its Supported Catalyst

Electrode material is essential to electrochemical technology, and it is one of the most important control factors for achieving electrocatalysis process. In this work, nano-powder of ruthenium-titanium composite oxides with different Ru mole ratios (Ru_xTi_1-xO₂, x=0.1, 0.15, 0.2, 0.25, 0.3) were synthesized from TiN nanoparticle and precursor by TiN impregnation-thermal-decomposition method, and then 20 wt% Pt or Pd was deposited onto this nano-powder by microwave-assisted polyol reduction method. The so-obtained electrocatalysts were used as catalysts for electrolysis of water and fuel cells. The structure, composition, electrocatalysis activity and stability of this type of catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), polarizationcurve, cyclic voltammetry (CV) and chronoamperometric measurements. We did research on the electrocatalysis oxidization mechanism of formic acid and methanol, and at the same time, the deactivation reason of electrocatalysts was discussed. It is significant and worthy to develop new types of fuel cells and electrolysis of water; and we hope to explore new ways for synthesizing new types of catalyst.(1) Nano-powder of ruthenium-titanium composite oxides (Ru_xTi_1-xO₂) was synthesized by TiN impregnation-thermal-decomposition method. The structure and composition of this type of catalyst was characterized by XRD and TEM, and results indicate that RuO2 and TiO2 formed a binary solid solution with claviform shape and rutile structure. The powders are less aggregation and smaller sizes of particles. Ru_xTi_1-xO₂ showed good electrocatalytic properties as characterized by oxygen evolution according to the polarization curves obtained from 0.5 mol/L H₂SO₄.(2) 20 wt% Pt was deposited onto Ru_0.2Ti_0.8O₂ by microwave-assisted polyol reduction method. The so-obtained composite was used as an effective anode catalyst for electrolysis of water and direct methanol fuel cell (DMFC). The XRD and TEM characterized results showed that Pt nanoparticles were well dispersed on the surface of Ru_0.2Ti_0.8O₂ which is in claviform shape and rutile structure, and most of the diameters of particles were within 3nm-5nm range. The polarization curve, cyclic voltammetry and chronoamperometric measurement results indicated that there was a good synergistic effect between Pt and support, so it had an excellent electrocatalytic activity and stability. The good stability of Pt/Ru_0.2Ti_0.8O₂ maybe owned to hydroxy provided could boost the oxidation of CO, the strong interaction between Pt and Ru_0.2Ti_0.8O₂ changed the surface properties of Pt, which make it free from the inactivation of CO.(3) 20 wt% of Pd was deposited onto Ru_xTi_1-xO₂ (x=0.2, 0.25, 0.3) by microwave-assisted polyol reduction method. The so-obtained composite was used as an effective anode catalyst for electrolysis of water and direct formic acid fuel cells (DFAFC). The structure and composition of this type of catalyst was characterized by XRD and TEM. Pd nanoparticles are well dispersed on the surface of the composite oxides in claviform shape and rutile structure. Cyclic voltammetry and chronoamperometric measurement results showed that the content of Ru can influence the electrocatalytic activity and stability of the catalysts towards direct oxidation of formic acid. Among the catalysts with different Ru mole ratios, Pd/Ru_0.3Ti_0.7O₂ catalyst had the highest electrocatalytic activity and stability. The electro-catalytic oxidation and deactivation analysis by cyclic voltammetry (CV) and polarization curves showed that the catalysts had good electrocatalytic activity for the direct oxidation of formic acid, and the deactivation of Pd might be caused by suboxides generated on the surface, which hinder the diffusion of formic acid on the surface of the catalyst. Deactivated catalyst can be reactivated by dissolution under open circuit potential, and cathodic reduction and anodic oxidation, electrocatalytic activity can be renewed.