Electrochemical growth of platinum nanostructures for enhanced ethanol oxidation (original) (raw)
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Electrochemical formation of platinum nanostructures for fuel cell applications
ICONN 2010 - Proceedings of the 2010 International Conference on Nanoscience and Nanotechnology, 2010
We report the electrodeposition of platinum on evaporated gold substrates, which provides a method of synthesising surfaces which are active towards the oxidation of methanol. The inclusion of an inorganic growth direction agent is seen to provide a means of altering both the morphology of the deposits as well as their electrocatalytic behaviour.
Journal of Catalysis, 2011
Ethanol electrooxidation reaction (EOR) pathways on polycrystalline platinum were studied with broadband sum-frequency generation (BB-SFG) spectroscopy and electrochemistry in unprecedented detail and under working fuel cell conditions. We present the first observation of adsorbed acetate and coadsorbed sulfuric acid anions with SFG and a discussion of their relation to the EOR. Surface-adsorbed intermediates such as CO on Pt atop sites and acetate are observed in both H 2 SO 4 and HClO 4 solutions. However, CO molecules on bridge sites and sulfuric acid anions are found in H 2 SO 4 only. At E < 0.5 V vs. Ag/AgCl, CO is the predominantly adsorbed species. Increasing the potential to E > 0.5 V results in the oxidative removal of CO and the adsorption of acetate anions. Experiments with isotopically labeled ethanol ( 12 CH 3 13 CH 2 OH) reveal information on the carbon-carbon bond cleavage and the subsequent CO formation. In particular, the methyl fragment (-12 CH x ) produces far less 12 CO and suggests methyl electroreduction to methane and/or the persistence of -CH x on the Pt surface.
Influence of structural defects on the electrocatalytic activity of platinum
Journal of Solid State Electrochemistry, 2008
Structural defects play major role in catalysis and electrocatalysis. Nanocrystalline (or nanostructured) materials composed of nanometer-sized crystallites joined via grain boundaries have been recognized for their specific structure and properties, differentiating them from single crystals, coarsely grained materials or nanometer-sized supported single-grained particles (Gleiter, Nanostruct Mater 1:1-19, 1992). In this paper, we use Pt electrodes, prepared by electrodeposition on glassy carbon and gold supports, as model nanocrystalline materials to explore the influence of grain boundaries and other structural defects on electrocatalysis of CO and methanol oxidation. We build on the recently established correlations between the nanostructure (lattice parameter, grain size, and microstrains) of electrodeposited Pt and the deposition potential (Plyasova et al., Electrochim. Acta 51:4447-4488, 2006) and use the latter to obtain materials with variable density of grain boundary regions. The activity of electrodeposited Pt in the oxidation of methanol and adsorbed CO exceeds greatly that for Pt(111), polycrystalline Pt, or single-grained Pt particles. It is proposed that active sites in nanostructured Pt are located at the emergence of grain boundaries at the surface. For methanol electrooxidation, the electrodes with optimal nanostructure exhibit relatively high rates of the "direct" oxidation pathway and of the oxidation of strongly adsorbed poisoning intermediate (CO ads), but not-too-high methanol dehydrogenation rate constant. These electrodes exhibit an initial current increase during potentiostatic methanol oxidation explained by the CO ads oxidation rate constant exceeding the methanol decomposition rate constant.
Early stages in the oxidation of ethanol at low index single crystal platinum electrodes
Journal of Electroanalytical Chemistry, 1997
Conventional electrochemical methods and in situ FTIR spectroscopy have been applied to study the early stages for adsorption and oxidation of ethanol at Pt(I Ii), Pt(110), and Pt(100). Spectroscopic results show that the electrooxidation of ethanol on all three surfaces is characterised by the formation of acetaldehyde, acetic acid and carbon dioxide as soluble products. Linearly and bridge bonded CO are identified as adsorbed species. At Pt(110) other surface species containing CH and COH bonds are observed. In the hydrogen region of the Pt(100) surface, the interconversion between bridge and linearly bonded CO, turns out to be a common feature during the electrooxidation of small organic molecules. The important role played by adsorbed water is discussed. Adsorption of ethanol is the rate determining step.
Chemistry and Materials, 2022
Platinum (Pt) nanoparticles were successfully prepared using square wave pulse deposition technique by varying the upper potential. The X-ray energy dispersive spectrum pattern confirmed the formation of Pt nanoparticles on the fluorinedoped tin oxide coated glass substrate. The results of scanning electron microscopy showed that the potential of 0.60 V was able to produced a large number of Pt particles with a unique morphology. The ethanol electrooxidation test conducted using cyclic voltammetry showed that Pt0.60v has the lowest charge transfer resistance value showing high catalytic activity which could be associated to the increase of particle number and its active sites that activated the redox reactions in the system.
Platinum Nanoparticles Supported on Carbon Nanodots as Anode Catalysts for Direct Alcohol Fuel Cells
International Journal of Electrochemical Science, 2017
Carbon nanodots (CNDs) were successfully synthesized employing a cheap and green method using oats as a starting material. The Pt/CNDs electrocatalyst was synthesized using carbon nanodots as a reductant and support material without adjusting the pH of the solution. The synthesized materials were characterized using Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller Nitrogen adsorption (BET), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Inductively coupled plasma optical emission spectroscopy (ICP-OES). The FTIR results proved that the synthesized carbon nanodots contain carboxylic acid functional groups which facilitate the attachment of Pt nanoparticles. The BET surface area for carbon nanodots was found to be 312.5 m 2 g-1 two times higher than that of commercial carbon. XPS results revealed the composition of the materials and the oxidation states of Pt in Pt/CNDs electrocatalyst. TEM images proved that the materials were of the nanoscale. XRD peaks proved that the carbon nanodots were amorphous and Pt (111) was present in the Pt/CNDs electrocatalyst. ICP-OES determined the platinum concentration in Pt/CNDs electrocatalyst to be 8.12%. The electrochemical oxidation of methanol and ethanol were studied by cyclic voltammetry (CV) and chronoamperometry (CA). Cyclic voltammetry results showed that the Pt/CNDs electrocatalyst prepared by this method exhibit superior performance for methanol and ethanol electro-oxidation at room temperature.
Electrochemically Promoted Catalysis: The Case of Ethanol Oxidation over Pt
Journal of Catalysis, 2002
Ethanol oxidation was investigated over polycrystalline Pt films deposited on 8 mol% Y 2 O 3-stabilized-ZrO 2 (YSZ) in the temperature range of 300-350 • C. It was found that electrochemical supply of oxygen anions (O 2−) to the Pt catalyst results in significant changes both in the rate of ethanol consumption and in the yield of acetaldehyde. Electrochemical supply of O 2− anions induces an enhancement of the reaction rate that was found typically 10 3-10 4 times larger than the Faradaic rate of O 2− supply and an almost seven-fold increase in the reaction yield to acetaldehyde. In the range of the applied currents, it was found that the catalytic activation energies of ethanol consumption and acetaldehyde formation can be lowered by 70 and 80%, respectively, with respect to the regular (open-circuit) values. The observed behavior is discussed and explained on the basis of the theory of NEMCA.
Lancet, 2011
Pt electrocatalysts supported on carbon nanocoils (CNCs) were prepared by the sodium borohydride (BM), formic acid (FAM) and ethylene glycol (EGM) reduction methods in order to determine the influence of the synthesis method on the physicochemical and electrochemical properties of Pt/CNC catalysts. For this purpose, physicochemical properties of these materials were studied by means of energy dispersive X-ray analyses, X-ray diffraction and N 2 -physisorption, whereas their electrochemical activity towards ethanol and carbon monoxide oxidation was studied using cyclic voltammetry and chronoamperometry. Furthermore, in order to complete this study, the results obtained for Pt/CNC catalysts were compared with those obtained for Pt catalysts supported on Vulcan XC-72R (commercial support) prepared by the same methods and for the commercial Pt/C catalysts from E-TEK. Results showed that, for all studied methods, CO oxidation occurred at more negative potentials on Pt/CNC catalysts than on Pt/Vulcan and Pt/C E-TEK ones. On the other hand, higher current densities for the ethanol electrooxidation were obtained when CNCs were used as support for BM and EGM. It is concluded that optimizing the synthesis method on CNC, materials with enhanced electrooxidation properties could be developed.
Journal of Power Sources
Well-dispersed Pt nanoparticles with controlled size and narrow size distribution were prepared by polyalcohol reduction of platinum acetylacetonate, using oleylamine as a capping agent. The particle size was varied from 3.5 nm to 11.5 nm by decreasing the amount of oleylamine added in the synthesis. Size selection of the as-prepared particles by solvent fractionation yielded nearly monodispersed Pt particles. The as-prepared particles were loaded on a carbon support by physical deposition, but showed no electrocatalytic activity due to the oleylamine bound to the particle surface. The particles were activated for electrocatalysis after heating the particles in air at 185 • C for 5 h, conditions that gave no particle-sintering and no oxidation. Cyclic voltammetry showed that the particles after the heat treatment in air were electrocatalytically active for methanol oxidation. The smaller 3.5 nm and 4.0 nm Pt particles had a higher intrinsic activity for methanol oxidation, but a lower tolerance to CO poisoning, compared with 6.0 nm, 9.5 nm and 11.5 nm particles. CO-stripping results suggest that CO is more easily oxidized on larger Pt particles.