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Designing highly efficient, low cost and long-term stable electro-catalysts is the key step for the commercial applications of fuel cells. Electro-oxidation of urea, a hydrogen-rich fuel, is the anodic reaction of direct urea fuel cells. Herein, defects-rich nickel nanoparticles grown on nickel foam as integrated electrodes have been designed and easily fabricated by incomplete reduction of Ni(OH) 2. The Ni2+ defects coupled with oxygen vacancies are proposed to be mainly present in the form of amorphous NiO x , which is the island phase in the metallic nickel nanoparticles and confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. The synergistic effect between metallic metal with high conductivity and numerous defects with good affinity to O contributes to the high catalytic activity towards oxidation of urea with an onset potential of 0.35 V vs Hg/HgO in 2 M KOH +0.33 M urea. Additionally, the defects-rich nickel nanoparticles present good long-term stability. • Defects-rich nickel nanoparticles were synthesized. • The defects-rich nickel nanoparticles show high catalytic activity towards urea oxidation. • It achieves the onset oxidation potential of 0.35 V vs. vs Hg/HgO. • The synergistic effect between metallic Ni and Ni2+ defects contributes to the high activity. [ABSTRACT FROM AUTHOR]

Carbon nanofibers (CNFs) decorated with Cu2O particles were grown on a Ni catalyst layer deposited on a Cu substrate by thermal. chemical vapor deposition from liquid petroleum gas. Ni catalyst nanoparticles with different sizes were produced in an electroplating system at 35˚C. These nanoparticles provide the nucleation sites for CNF growth, removing the need for a buffer layer. High temperature surface segregation of the Cu substrate into the Ni catalyst layer and its exposition to O2 at atmospheric environment, during the CNFs growth, lead to the production of CNFs decorated with Cu2O particles. The surface morphology of the Ni catalyst films and grown CNFs over it was studied by scanning electron microscopy. Transmission electron microscopy and Raman spectroscopy revealed the formation of CNFs. The selected area electron diffraction pattern and electron diffraction studies show that these CNFs were decorated with Cu2O nanoparticles.

Carbon nanofibers (CNFs) decorated with Cu2O particles were grown on a Ni catalyst layer deposited on a Cu substrate by thermal. chemical vapor deposition from liquid petroleum gas. Ni catalyst nanoparticles with different sizes were produced in an electroplating system at 35°C. These nanoparticles provide the nucleation sites for CNF growth, removing the need for a buffer layer. High temperature surface segregation of the Cu substrate into the Ni catalyst layer and its exposition to O2 at atmospheric environment, during the CNFs growth, lead to the production of CNFs decorated with Cu2O particles. The surface morphology of the Ni catalyst films and grown CNFs over it was studied by scanning electron microscopy. Transmission electron microscopy and Raman spectroscopy revealed the formation of CNFs. The selected area electron diffraction pattern and electron diffraction studies show that these CNFs were decorated with Cu2O nanoparticles. [ABSTRACT FROM AUTHOR]