Enhanced performance of urea electro-oxidation in alkaline media on PtPdNi/C, PtNi/C, and Ni/C catalysts synthesized by one-pot reaction from organometallic precursors

Abstract In this work, one-pot synthesis of metal nanoparticles from organometallic precursors namely Pt2(dba)3, Pd(dba)2 and Ni(cod)2 employing octylamine as stabilizer and carbon Vulcan XC-72R as support was carried out to obtain Ni/C, PtNi/C, and PtPdNi/C catalysts. Transmission Electron Microscopy (TEM) analysis of the as-synthesized materials shows semi-spherical particles with good dispersion on the carbon Vulcan having sizes of 3.2, 2.5 and 2.2 nm for Ni, PtNi, and PtPdNi, respectively. X-ray diffraction (XRD) confirms the presence of Pt, Pd, and Ni FCC crystal structure and reveals the formation PtNi and PtPdNi solid solutions. Additionally, XPS Pt4f core-level spectra shown a shift to lower binding energy at the alloy formation due to the addition of nickel and palladium evidencing a solid solution. The tri-metallic PtPdNi/C catalyst exhibits better performance than PtNi/C and Ni/C catalysts toward urea oxidation reaction in alkaline conditions suggesting an activity enhancement due to the oxidized Ni species from NiOOH. Using differential electrochemical mass spectroscopy (DEMS), it has been demonstrated that species such as NH3 (m/z = 17), CO2 -or N2O- (m/z = 44) and NO (m/z = 30) are generated during polarization at 4 mV s−1. Concomitant pollution control, this study demonstrated that urea could be used as a source of protons for energy generation in fuel cells systems.