Synthesis and characterization of LaNiO3-based platinum catalyst for methanol oxidation

Conductive perovskite type lanthanum nickelate (LaNiO3) powders are prepared through a nitrilotriacetic acid (NTA) precursor complex route. Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) results indicate complete decomposition of the precursor complex to LaNiO3 at 900 °C in 4 h. Powder X-ray diffraction (XRD) patterns confirm the formation of the perovskite. Scanning electron microscopic (SEM) analysis and particle size determination reveal the formation of micron-sized particles, probably by the agglomeration of nanoparticles of LaNiO3. Cyclic voltammetry (CV) is used to assess the electrochemical activity of LaNiO3 in comparison with Pt/C, as well as the addition of small amounts of Pt/C to LaNiO3 or a Vulcan XC-72R carbon support of three different compositions, towards methanol electro-oxidation. LaNiO3 does not show much activity for methanol oxidation. However, a synergistic effect is observed when LaNiO3 is mixed with small amounts of Pt/C. The increased oxidation current due to the addition of LaNiO3 to small amounts of Pt/C in the three mixtures containing LaNiO3 is attributed to either the additional catalyst site of the perovskite in addition to the Pt site, or the removal of CO poisoning on the Pt surface by the surface oxygen of the adjacent perovskite.