• Energy Research

AbstractNickel nanoparticles supported by commercial carbon paper (CP) are prepared by pulsed laser deposition with deposition time of 3, 6, and 12 min as a catalyst for urea electro-oxidation. The surface conditions and the morphologies of the prepared electrodes have been characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Urea electro-oxidation reaction in KOH solution on the Ni/CP electrodes is investigated by cyclic voltammetry and chronoamperometry. The results show that the electrode with less Ni nanoparticle agglomeration shows higher peak current density, which was achieved in the 3 min deposition samples when normalized by electroactive surface areas. However, the highest current normalized by the area of the carbon paper was achieved in the 6 min deposition sample due to the larger quantity of Ni nanoparticles. All the samples show good stability. Our results suggest that the low density, low cost, and environmental friendly CP can be used as support for Ni nanoparticle as a catalyst for urea electro-oxidation. It thus has great potential for many applications involving urea oxidation, such as wastewater treatments.

International audience ; This study investigated the influence of dopants (Gd, Nb, Pr, and Zr) on the performance of Pt/CexMe1-xO2-γ/Al2O3 catalysts for the methane steam reforming (SRM) at 1073 K and at different space velocities. In-situ XRD, in-situ XANES, and Raman spectroscopy revealed the formation of a solid solution on the supports with Gd, Pr and Zr and an improvement in reducibility. No evidence of complete niobium inclusion into the ceria framework was observed and AlNbO4 and CeNbO4 phases were detected. All catalysts exhibited a severe initial deactivation, however, with Pt/CeNb/Al being most stable. Analyses of all spent catalysts revealed a negligible carbon deposition during the catalytic tests. TEM, XRD and N2 physisorption showed a collapse of the alumina structure and sintering of Pt particles as causing the early deactivation. The formation of segregated phases for Nb-doped ceria improved the thermal resistance of alumina and provided a closer contact with Pt crystallites, resulting in better stability.