Hydrazine oxidation at preferentially oriented Pt (100) nanowires array electrodes
- PDF / 612,991 Bytes
- 6 Pages / 612.12 x 792.12 pts Page_size
- 87 Downloads / 212 Views
Hydrazine oxidation at preferentially oriented Pt (100) nanowires array electrodes S. Garbarino, A. Ponrouch, E. Bertin and D. Guay Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Bd Lionel Boulet, J3X 1S2, Varennes, Québec, CANADA
ABSTRACT In this study, platinum was electroplated onto bare Ti substrates (Pt black) and through a porous AAO membrane (Pt nanowires). The morphology of the deposits was observed by scanning electron microscopy. Preferential orientation along the (100) direction into the bulk material was evidenced through XRD analysis, as well as at the nanowire surface by using electrochemical characterization. These highly oriented Pt nanowires exhibited an increased activity for the electrocatalytic oxidation of hydrazine oxidation, as compared to Pt black.
INTRODUCTION Many studies have been conducted to find an alternative to the use of Pt in heterogeneous catalysis. However, the electrocatalytic activity of Pt being high, it is challenging to identify an interesting alternative. Therefore, Pt remains the most extensively used catalyst for several dehydrogenation reactions. However, platinum is costly and scarce and it is of interest to minimize the amount of material used and to increase the electrocatalytic of Pt. Several strategies have been proposed to maximize Pt utilization. Among them, increasing the platinum surface-tomass (S/M) ratio is the preferred one, and this has been achieved by the synthesis of isolated nanoparticles (1) and 1D nanostructures (2). On the other hand, the strategies developed to increase the electrocatalytic activity of Pt are mostly based on the formation of Pt-based alloy (3). Increased electrocatalytic activities have also been demonstrated for several surface crystallographic structure of Pt. For example, the Pt (111) is the most active surface structure for the reduction of O2 in KOH solution (4). Likewise, Pt (100) is the most electroactive surface structure for the oxidation of NH3 (5) and N2H4 (6). It would thus be interesting to be able to prepare Pt electrocatalysts showing both a high surface-to-mass ratio and a large fraction of preferentially oriented surface structure In this paper, it will be shown that Pt surface with high aspect ratio and (100) bulk and surface orientation can be grown in the form of Pt nanowires. The electrocatalytic activity of these (100) preferentially oriented Pt nanowires for the oxidation of hydrazine will be presented. EXPERIMENTAL Pt was electroplated on Ti substrates that were prepared as described previously (7). Platinum black (Pt B) was obtained by electrochemical deposition on bare Ti substrates, whereas nanowires (NW) were prepared by deposition through a porous anodic aluminum oxide (AAO) membrane. In both cases, the same coulombic charges (ca. 60 C cm-2) were applied to ensure the same platinum loading onto Ti. Following deposition, the AAO membrane was dissolved by
immersion in 1 M NaOH for 2 h at room temperature. The morphology of the deposits was observed using a
Data Loading...
