ABSTRACTS
Journal Archive
ABSTRACTS
of current literature on the platinum metals and their alloys
PROPERTIES
The Stabilization of Pt3Al Phase with L12 Structure in Pt–Al–Ir–Nb and Pt–Al–Nb Alloys
C. HUANG, Y. YAMABE-MITARAI and H. HARADA, J. Alloys Compd., 2004, 366, (1–2), 217–221
The structure of the Pt3Al phase in the title alloys was investigated using SEM, XRD, DTA and TEM techniques. The alloys were prepared using pure metal powders by an arc-melting method in an Ar atmosphere. The structure form was determined to be cubic L12. The stabilisation of the L12-Pt3Al structure at room temperature was due to the effect of Nb.
Phase Transformation and Magnetic Anisotropy of an Iron–Palladium Ferromagnetic Shape-Memory Alloy
J. CUI, T. W. SHIELD and R. D. JAMES, Acta Mater., 2004, 52, (1), 35–47
The f.c.c.-f.c.t. transformation in Fe7Pd3 is a weak first-order thermoelastic transition. The latent heat of the f.c.c.-f.c.t. transformation is 10.79 ± 0.01 J cm−3. Magnetic measurements indicate the tetragonal martensitic phase has easy axes in the [1 0 0] and [0 1 0] (a-axes) directions while [0 0 1] (c-axis) is the hard direction.
Microstructure and Mechanical Properties of Ru–Al–Mo Alloys
T. D. REYNOLDS and D. R. JOHNSON, Intermetallics, 2004, 12, (2), 157–164
Alloys in the Ru-Al-Mo system were produced by arc-melting and a cold crucible Czochralski technique. One set of alloys consisted of eutectic microstructures between RuAl and a b.c.c. (Mo, Ru) solid solution. The other set of alloys consisted of RuAl and a h.c.p. (Ru, Mo) solid solution; a change from eutectic to peritectic solidification occurs as the Mo concentration increases. The RuAl-h.c.p. (Ru, Mo) eutectic microstructure was found to consist of RuAl fibres embedded in a (Ru, Mo) matrix.
CHEMICAL COMPOUNDS
Synthesis, Structure, and Reactivity of Arylfluoro Platinum(II) Complexes
P. NILSSON, F. PLAMPER and O. F. WENDT, Organometallics, 2003, 22, (25), 5235–5242
trans-[PtPhFL2] (L = PPh3 (1) and PMe2Ph (2)) were synthesised and then (1) was characterised by X-ray crystallography. The equilibrium constant for the substitution of F− trans to phenyl in (1) by Cl− and I− was determined. The Pt has preference for the halide: I > Cl > F. (1) and (2) reacted with Me3SnPh within 2–15 min. (1) gave trans-[PtPhMe(PPh3)2], whereas (2) gave trans-[PtPhMe(PMe2Ph)2] and trans-[PtPh2(PMe2Ph)2].
Gas-Phase Studies on the Reactivity of the Azido(diethylenetriamine)platinum(II) Cation and Derived Species
S. WEE, J. M. WHITE, W. D. McFADYEN and R. A. J. O'HAIR, Aust. J. Chem., 2003, 56, (12), 1201–1207
Collision-induced dissociation and ion–molecule reactions of [Pt(dien)N]+ (1) were carried out in the gas phase. Labelling studies (15N and 2H labelling of the dien ligand) were also employed. The H atoms of both the amino groups and the C backbone of the dien ligand are involved in loss of NH3 from (1). The crystal structure of [Pt(dien)3]+ was also determined.
Coordination of Amines to Palladium(II) Complexes of N21, N22-Bridged Porphyrins
Y. TAKAO, T. TAKEDA and J. SETSUNE, Bull. Chem. Soc. Jpn., 2003, 76, (8), 1549–1553
Pyridine and ethylenediamine (en) reacted with the title Pd(II) porphyrins to give mixed-ligand Pd(II) complexes. The splitting pattern in the Soret region of their UV-vis spectra was dependent on whether the porphyrinato Pd(II) was coordinated by neutral ligands or anionic ligands. In the 1H NMR spectra of en complexes of porphyrinato Pd(II), signal broadening of porphyrin β-pyrrole protons and a chemical shift change of en protons were seen in the dichloride in comparison with the bis(perchlorate).
Synthesis and Reactivity of Bucky Ruthenocene Ru(η5-C60Me5)(η5-C5H5)
Y. MATSUO, Y. KUNINOBU, S. ITO and E. NAKAMURA, Chem. Lett., 2004, 33, (1), 68–69
Metathetical coupling of Ru(η5-C60Me5)Cl(CO)2 and CpNa resulted in a molecular hybrid of ruthenocene and fullerene: Ru(η5-C60Me5)(η5-C5H5) (1). In (1), the bonding between the Ru atom and the C60Me5 ligand as well as between the metal atom and the Cp group is very different from that of known ferrocene and ruthenocene compounds. (1) is quite reactive compared to the rather stable bucky ferrocene compound.
Specific Heat of Sr4Ru3O10
X. N. LIN, V. A. BONDARENKO, G. CAO and J. W. BRILL, Solid Commun., 2004, 130, (3–4), 151–154
A flux grown (FG) sample of Sr4Ru3O10 (1) had a sharp mean-field-like anomaly at the onset of magnetic order, TC = 102 K, but a much broader anomaly, indicative of residual heterogeneity, was observed for an image furnace grown sample. Even for the FG sample, however, the anomaly was at least an order of magnitude smaller than would be expected for complete ordering of the spins. Neither sample exhibited an anomaly at TM ∼ 50 K. Anomalous behaviour was observed at low temperatures for both samples, indicative of the unusual magnetic order in (1).
ELECTROCHEMISTRY
IrO2/SnO2 Electrodes: Prepared by Sol–Gel Process and Their Electrocatalytic for Pyrocatechol
Y. LIU, Z. LI and J. LI, Acta Mater., 2004, 52, (3), 721–727
IrO2/SnO2 (10%:90%, molar ratio) electrodes (1) were prepared by the sol-gel method. Oxide films prepared at low temperature were in an amorphous state, while hydrous IrO2 crystal and cassiterite phase SnO2 were formed at 300°C or even to 500°C. (1) with the highest electroactivity were formed at 400°C. For the electrocatalysis of pyrocatechol on (1), a quasi-reversible process occurred. The detection limit of pyrocatechol was 5 × 10−3 mM.
NiO-Based Composite Electrode with RuO2 for Electrochemical Capacitors
X. M. LIU and X. G. ZHANG, Electrochim. Acta, 2004, 49, (2), 229–232
NiO/RuO2 composite materials were prepared by the coprecipitation method followed by heat treatment. XRD spectra indicated that the Ru oxide particles were coated by NiO particles. RuO2 partly introduced into NiO-based electrodes improved their electrochemical performance and capacitive properties. A maximum specific capacitance of 210 F g−1 was achieved for a NiO-based composite electrode with 10 wt.% RuO2 at –0.4 to 0.5 V in 1 mol l−1 KOH solution. Chemically modified composite electrodes had more stable cycling properties than those of physically modified electrodes.
PHOTOCONVERSION
The Photohydrochlorination of Platinum(IV) Chloride in Chloroform
P. E. HOGGARD, A. J. BRIDGEMAN, H. KUNKELY and A. VOGLER, Inorg. Chim. Acta., 2004, 357, (3), 639–643
When irradiated by light at 240 nm, PtCl4 in CHCl3 was converted to H2PtCl6, via a Pt(V) intermediate. When irradiated by light at > 265 nm, PtCl4 was converted to H2PtCl4 and H2PtCl6 in equal amounts. At > 265 nm, the reaction may proceed by Cl dissociation from a LMCT excited state of Pt(IV), through a Pt(III) intermediate.
Multicolored Electrogenerated Chemiluminescence from Ortho-Metalated Iridium(III) Systems
B. D. MUEGGE and M. M. RICHTER, Anal. Chem., 2004, 76, (1), 73–77
Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyri-dyl))-Ir(III), F(Ir)pic, is a blue emitter (λECL ∼ 470 nm) and bis[2,(2′-benzothienyl)pyridinato-N,C3′](acetyl-acetonate)Ir(III), (btp)2Ir(acac), emits in the red (λECL ∼ 600 nm). The ECL solution spectrum of each complex is identical to its photoluminescence spectrum, indicating the same metal-to-ligand excited states. The oxidative reductive coreactant tri-n-propylamine was used. ECL intensity increased in the presence of Triton X-100 surfactant: up to 6-fold for F(Ir)pic and up to 20-fold for (btp)2Ir(acac).
Enhanced Electrochemiluminescence from Os(phen)2(dppene)2+ (phen = 1,10-phenanthroline and dppene = bis(diphenylphosphino)ethene) in the Presence of Triton X-100 (Polyethylene Glycol tert-Octylphenyl Ether)
J. WALWORTH, K. J. BREWER and M. M. RICHTER, Anal. Chim. Acta, 2004, 503, (2), 241–245
The anodic oxidation of Os(phen)2(dppene)2+ produced electrochemiluminescence (ECL) in the presence of tri-n-propylamine (TPrA) in aqueous surfactant solution. Increases in ECL efficiency (≥ 3-fold) and TPrA oxidation current (≥ 2-fold) were observed in Triton X-100 surfactant media. Experiments indicated adsorption of surfactant on the electrode surface.
Can Clay Emit Light? Ru(bpy)32+-Modified Clay Colloids and Their Application in the Detection of Glucose
P. Y. LIANG, P. W. CHANG and C. M. WANG, J. Electroanal. Chem., 2003, 560, (2), 151–159
Electrochemical-quartz-crystal-microbalance techniques showed that Ru(bpy)33+ can be adsorbed by montmorillonite K10 clay colloids. The resulting clay particles (1) emitted light (λem = 610 nm) when they were fabricated as thin films sandwiched by two conductive ITO electrodes with opposite biases. A glucose optrode was fabricated using (1) and glucose oxidase. The electrochemiluminescence signals behaved as a function of [glucose]: 0.1–10 mM at pH 10. At this pH, the detection limit reached 0.1 mM.
Photoelectrochemical Properties of Supramolecular Species Containing Porphyrinand Ruthenium Complexes on TiO2 Films
A. F. NOGUEIRA, A. L. B. FORMIGA, H. WINNISCHOFER,M. NAKAMURA, F. M. ENGELMANN, K. ARAKI and H. E. TOMA, Photochem. Photobiol. Sci., 2004, 3, (1), 56–62
Supramolecular species based on porphyrin and Ru(II) polypyridyl complexes were used as sensitisers on mesoporous TiO2. The peripheral Ru complexes act as an antenna system by transferring electronic charge to the porphyrin ring. meso-Tetrapyridylpor-phyrin coordinated to two Ru complexes converted 21% of the incident photons into current after excitation at the Soret band.
Photosensitization of Nanocrystalline SnO2 Films with a tris (2,2′-Bipyridine) Ruthenium(II)-Fullerene Dyad
C. NASR, D. M. GULDI, M. MAGGINI, F. PAOLUCCI and S. HOTCHANDANI, Fullerenes, Nanotubes, Carbon Nanostruct., 2003, 11, (2), 121–133
A photoelectrochemical study of a tris (2,2′-bipyridine)ruthenium(II)-C60 donor–acceptor dyad adsorbed on nanocrystalline semiconductor SnO2 electrodes was carried out. The results showed that the incident photon-to-current conversion efficiency of the dyad-based photoelectrochemical cells is ∼ 10%.
Novel and Efficient Organic Liquid Electrolytes for Dye-Sensitized Solar Cells Based on a Ru(II) Terpyridyl Complex Photosensitizer
K. HARA, T. NISHIKAWA, K. SAYAMA, K. AIKA and H. ARAKAWA, Chem. Lett., 2003, 32, (11), 1014–1015
An electrolyte composed of 1-ethyl-3-methylimidazolium iodide, I2 and MeCN solvent has been developed for a nanocrystalline TiO2 solar cell sensitised with a Ru(II) terpyridyl complex (1). Trithiocyanato 4,4′,4H-tricarboxy-2,2′:6′,2-terpyridine Ru(II) (black dye) was used as (1). Under AM 1.5 irradiation (100 mW cm–2), a solar energy-to-electricity conversion efficiency of 8.0% was achieved.
APPARATUS AND TECHNIQUE
Thin Film Dissolved Oxygen Sensor Based on Platinum Octaethylporphyrin Encapsulated in an Elastic Fluorinated Polymer
R. N. GILLANDERS, M. C. TEDFORD, P. J. CRILLY and R. T. BAILEY, Anal. Chim. Acta, 2004, 502, (1), 1–6
The title sensor (1) was fabricated by encapsulating Pt octaethylporphyrin in an O2 permeable elastic fluorinated copolymer matrix. Phosphorescence, which was partially quenched by dissolved O2, was observed by (1) when (1) was immersed in H2O. At elevated temperatures the dye aggregated. (1) exhibits good sensitivity, rapid response and photostability.
Carbonate-Melt Oxidized Iridium Wire for pH Sensing
M. WANG and S. YAO, Electroanalysis, 2003, 15, (20), 1606–1615
A thick, uniform and dense ceramic oxide layer was grown by oxidation on the surface of an Ir wire in molten Li carbonate. After treatment in acid solution, the hydrated oxide layer was characterised as Li0.86IrO2.34(OH)0.76·0.39H2O (1). An electrode made with a film of (1) exhibited good pH sensitivity and stability, even in strong acid/base solutions. The electrode has excellent long term stability over 2.5 years.
HETEROGENEOUS CATALYSIS
The Influence of Ir and Pt Addition on the Synthesis of Fullerenes at Atmospheric Pressure
G. N. CHURILOV, R. B. WEISMAN, N. V. BULINA, N. G. VNUKOVA, A. P. PUZIR, L. A. SOLOVYOV, S. M. BACHILO, D. A. TSYBOULSKI and G. A. GLUSHENKO, Fullerenes, Nanotubes, Carbon Nanostruct., 2003, 11, (4), 371–382
The addition of metallic Pt and Ir to a fullerene-forming atmospheric-pressure plasma reactor influenced the generation of carbonaceous products. The added metals were efficiently dispersed into the plasma. The addition of Pt increased the proportion of C60 oxides and decreased the proportion of higher fullerenes, whereas Ir caused a noticeable shift in the fullerene distribution towards C60. The Ir also caused a reduction of the soot particle size and the formation of a large quantity of C nanotubes.
Renewable Hydrogen from Ethanol by Autothermal Reforming
G. A. DELUGA, J. R. SALGE, L. D. SCHMIDT and X. E. VERYKIOS, Science, 2004, 303, (5660), 993–997
EtOH and EtOH-H2O were found to be converted directly into H2 with ∼ 100% selectivity and > 95% conversion, with a residence time on a Rh/CeO2 catalyst of < 10 ms. The reactions run at ∼ 700°C, but as the process is exothermic, the starting mixture only needs to be heated to ∼ 140°C. The mixture is then cooled to 400°C and passed over a Pt/CeO2 catalyst, where any CO reacts with hot H2O to give CO2 and H2. Onboard reforming of liquid fuel into H2 provides an alternative to storing H2 for fuel cells.
Transient Studies of Direct N2O Decomposition over Pt–Rh Gauze Catalyst. Mechanistic and Kinetic Aspects of Oxygen Formation
E. V. KONDRATENKO and J. PÉREZ-RAMÍREZ, Catal. Lett., 2003, 91, (3–4), 211–216
Transient experiments were carried out in a temporal analysis of products (TAP) reactor by pulsing N216O over 18O-pretreated Pt-Rh gauze catalyst at 1073–1273 K. From isotopic studies and fitting of transient data from N2O, N2 and O2, two separate routes for O2 formation during catalytic N2O decomposition were identified. These are: (a) interaction of N2O with adsorbed O species formed from N2O, and (b) recombination of adsorbed O species on the catalyst surface. The relative contributions of (a) and (b) depend on the reaction temperature.
Microwave-Assisted Catalytic Transfer Hydrogenation of Safflower Oil
B. L. A. PRABHAVATHI DEVI, M. S. L. KARUNA, K. NARASIMHA RAO, P. S. SAIPRASAD and R. B. N. PRASAD, JAOCS, 2003, 80, (10), 1003–1005
Catalytic transfer hydrogenation (CTH) of safflower oil using aqueous ammonium formate as H donor and Pd/C as catalyst was carried out in a closed vessel under controlled microwave irradiation conditions. Good selectivity in the complete reduction of linoleic acid to mono-unsaturated acid was achieved with a slight increase in stearic acid, compared to other reported CTH methods. No emulsifier or high ratios of H2O to oil were required.
Improvement of Catalyst Durability by Deposition of Rh on TiO2 in Photooxidation of Aromatic Compounds
H. EINAGA, T. IBUSUKI and S. FUTAMURA, Environ. Sci. Technol., 2004, 38, (1), 285–289
The deposition of Rh onto TiO2 improved the TiO2 catalyst durability in benzene photooxidation. The role of Rh0 was to reduce the amount of intermediates and byproducts on the catalyst surface. A Rh loading of 0.5–1.0 wt.% produced the highest reaction rate. The deactivation of Rh/TiO2 was prevented by heat treatment in a flow of H2 or N2 after the photoirradiation in humidified air.
HOMOGENEOUS CATALYSIS
Process Development and Pilot Plant Scale Synthesis of Spiro[3.5]nonane-6,8-dione
T. E. LEHMANN, O. KUHN and J. KRÜGER, Org. Process Res. Dev., 2003, 7, (6), 913–916
A two step pilot plant process for the production of spiro[3.5]nonane-6,8-dione has been developed. The first step is the epoxidation of spiro[3.5]non-7-en-6-one mediated by sodium perborate. The resulting crude epoxide afforded spiro[3.5]nonane-6,8-dione in 26% overall yield via a Pd-catalysed rearrangement. Pd(PPh3)4 was generated in situ from Pd(OAc)2 and PPh3 in the presence of triethylamine as the reducing agent. Pd(PPh3)4 formed the active catalytic species upon reaction with rac-BINAP.
Palladium-Catalyzed Aryl-Amidation. Synthesis of Non-Racemic N-Aryl Lactams
R. G. BROWNING, V. BADARINARAYANA, H. MAHMUD and C. J. LOVELY, Tetrahedron, 2004, 60, (2), 359–365
The Buchwald-Hartwig aryl amination method was used to obtain a series of chiral, non-racemic N-aryl pyrrolidinones from a common pyrrolidinone precursor and the corresponding aryl bromide. The Buchwald catalyst/ligand system was Pd2 dba3/ Xantphos. The stereochemical integrity of the N-aryl lactam after cross-coupling was proven by synthesis of the racemic compounds and comparison by 1H NMR spectroscopy using Pirkle's chiral solvating agent.
Palladium Catalyzed Reaction in Aqueous DMF: Synthesis of 3-Alkynyl Substituted Flavones in the Presence of Prolinol
M. PAL, V. SUBRAMANIAN, K. PARASURAMAN and K. R. YELESWARAPU, Tetrahedron, 2003, 59, (48), 9563–9570
(S)-Prolinol facilitated the coupling reaction of terminal alkynes with 3-iodoflavone using (PPh3)2PdCl2 as catalyst and CuI as cocatalyst in aqueous DMF. No significant side reactions such as dimerisation of terminal alkynes or opening of the flavone occur. This is a mild and convenient method for the synthesis of 3-alkynyl substituted flavones of potential biological interest.
Cationic Rhodium(I)/PPh3 Complex-Catalyzed Dehydrogenation of Alkanethiols to Disulfides under Inert Atmosphere
K. TANAKA and K. AJIKI, Tetrahedron Lett., 2004, 45, (1), 25–27
[Rh(cod)2]BF4/PPh3 was an effective catalyst system for the dehydrogenation of primary or secondary alkanethiols to symmetrical disulfides under an inert atmosphere of Ar with CH2Cl2 as the solvent. The highest yield of disulfides was achieved at 4°C for 1 h. A longer reaction time (16 h) for the reaction of a primary alkanethiol at the same temperature decreased the yield of disulfides. This dehydrogenation reaction is reversible and the formation of disulfide is a kinetically favourable process.
Rhodium Catalysed Coupling Reaction of Myrcene with Ethyl Acetoacetate in the Ionic Liquid1-Ethyl-3-methylimidazolium Triflimide
K. DHANALAKSHMI and M. VAULTIER, Tetrahedron, 2003, 59, (50), 9907–9911
[RhCl(COD)]2/TPPMS (triphenylphosphinemonosulfonate sodium salt) can be used for the coupling reaction of myrcene with ethyl acetoacetate in the title ionic liquid [emim][NTf2]. The coupling product was obtained in 93% isolated yield without formation of side product. The catalytic system could not be recycled due to its deactivation.
Phosphabarrelene-Rhodium Complexes as Highly Active Catalysts for Isomerization Free Hydroformylation of Internal Alkenes
B. BREIT and E. FUCHS, Chem. Commun., 2004, (6), 694–695
Phosphabarrelene-Rh complexes (1) were shown to be extremely active hydroformylation catalysts. Turnover frequencies ≤ 12,000 h−1 were observed for the hydroformylation of internal cyclic olefins. (1) can enable a position-selective hydroformylation of an internal double bond (C=C) essentially free of alkene isomerisation to occur.
Numerical Modeling of Differential Kinetics in the Asymmetric Hydrogenation of Acetophenone by Noyori's Catalyst
R. HARTMANN and P. CHEN, Adv. Synth. Catal., 2003, 345, (12), 1353–1359
An analysis of the catalytic cycle by which trans-RuCl2[(S)-binap][ (S, S)-dpen] asymmetrically hydrogenates acetophenone combines numerical integration of the rate equations and experimental measurement of the time dependence of rates, rather than concentrations. The method yields rate constants for activation, dihydrogen cleavage, and hydride transfer. The turnover-limiting step changes from dihydrogen cleavage to hydride transfer if H2 pressure is increased, and this also occurs during the acetophenone hydrogenation under typical conditions.
FUEL CELLS
The Role of the WO x Ad-Component to Pt and PtRu Catalysts in the Electrochemical CH3OH Oxidation Reaction
L. X. YANG, C. BOCK, B. MacDOUGALL and J. PARK, J. Appl. Electrochem., 2004, 34, (4), 427–438
High surface area catalysts, Pt/C, PtWOx/C, PtRu/C and PtRuWOx/C, were prepared via a chemical reduction route using single metal precursor salts. The addition of Ru decreased the particle size. The Ru was found to be partly incorporated into the f.c.c. lattice of Pt and to form a single Ru catalyst component. The PtRuWOx/C catalyst has a high degree of catalyst particle agglomeration. Both Ru containing catalysts showed significantly higher activities for the CH3OH oxidation reaction.
Homogeneous and Controllable Pt Particles Deposited on Multi-Wall Carbon Nanotubes as Cathode Catalyst for Direct Methanol Fuel Cells
W. LI, C. LIANG, W. ZHOU, J. QUI, H. LI, G. SUN and Q. XIN, Carbon, 2004, 42, (2), 436–439
The size of deposited Pt particles on multi-wall nanotubes (MWNTs) was controlled by using different concentrations of ethylene glycol-deionised (DI) H2O. The Pt loading was ∼ 10 wt.% for all the samples. The Pt/MWNTs produced using ethylene glycol-5% DI H2O exhibit higher O reduction reaction activity and superior cell performance in DMFC tests, than those from 0%, 40% and 70% DI H2O.
Mechanism of Preparation Process and Characterization of Highly Dispersed Pt/C Cathode Electrocatalyst for Direct Methanol Fuel Cells
Z. ZHOU, W. ZHOU, L. JIANG, S. WANG, G. WANG, G. SUN and Q. XIN, Chin. J. Catal., 2004, 25, (1), 65–69
A modified polyol process was used to prepare 40% Pt/C (1) for DMFCs. Highly dispersed Pt nanoparticles with narrow size distribution (mean size of 2.9 nm) supported on C were obtained. DMFC tests indicated that (1) had better electrocatalytic activity and stability for the O reduction reaction in DMFCs than its commercial equivalent. The redox reaction between PtCl62− and ethylene glycol was confirmed to take place via a single-step reaction path.
Analysis of the High-Temperature Methanol Oxidation Behaviour at Carbon-Supported Pt–Ru Catalysts
A. S. ARICÒ, V. BAGLIO, A. DI BLASI, E. MODICA, P. L. ANTONUCCI and V. ANTONUCCI, J. Electroanal. Chem., 2003, 557, 167–176
MeOH oxidation (1) at three Pt–Ru catalysts varying by the concentration of active phase on the C support was investigated at 80–130°C. When the catalyst had intrinsically high catalytic activity the fuel cell performance was enhanced, but the MeOH reaction rate was less influenced by an increase in coverage of active species. Catalysts with a higher degree of alloying and metallic behaviour on the surface are more active towards (1).
Preparation of Pt–Ru Bimetallic Anodes by Galvanostatic Pulse Electrodeposition: Characterization and Application to the Direct Methanol Fuel Cell
C. COUTANCEAU, A. F. RAKOTONDRAINIBÉ, A. LIMA,E. GARNIER, S. PRONIER, J.-M. LÉGER and C. LAMY, J. Appl. Electrochem., 2004, 34, (1), 61–66
Using a galvanostatic pulse electrodeposition technique, Pt and Ru were electrodeposited on C electrodes to prepare DMFC anodes (1) with different Pt:Ru atomic ratios. Most of (1) consisted of 2 mg cm−2 of Pt-Ru alloy particles with the desired composition and with particle sizes of 5–8 nm. Electrochemical tests in a single DMFC found that the best Pt:Ru atomic ratio at 50–110°C was 80:20.
Carbon-Supported Pt–Fe Alloy as a Methanol-Resistant Oxygen-Reduction Catalyst for Direct Methanol Fuel Cells
A. K. SHUKLA, R. K. RAMAN, N. A. CHOUDHURY, K. R. PRIOLKAR, P. R. SARODE, S. EMURA and R. KUMASHIRO, J. Electroanal. Chem., 2004, 563, (2), 181–190
The electrocatalyst Pt-Fe/C crystallises in an ordered f.c.t. crystal structure with higher proportions of active Pt sites than Pt/C. Pt-Fe/C exhibits significantly high O reduction activity in the presence of MeOH, while Pt/C shows a MeOH poisoning effect under similar conditions.
ELECTRICAL AND ELECTRONIC ENGINEERING
Molecule-Independent Electrical Switching in Pt/Organic Monolayer/Ti Devices
D. R. STEWART, D. A. A. OHLBERG, P. A. BECK, Y. CHEN,R. STANLEY WILLIAMS, J. O. JEPPESEN, K. A. NIELSEN and J. FRASER STODDART, Nano Lett., 2004, 4, (1), 133–136
Electronic devices (1) comprising a Langmuir-Blodgett molecular layer sandwiched between planar Pt and Ti metal electrodes were shown to function as switches and tunable resistors over a 102–105 Ω range under current or voltage control. Reversible hysteretic switching and resistance tuning was qualitatively similar for the very different molecular species: Cd eicosanoate salt, an amphiphilic [2]rotaxane (R) and the dumbell-only component of R.
Structural and Morphological Characterization by Energy Dispersive X-ray Diffractometry and Reflectometry Measurements of Cr/Pt Bilayer Films
B. PACI, A. GENEROSI, V. R. ALBERTINI, E. AGOSTINELLI,G. VARVARO and D. FIORANI, Chem. Mater., 2004, 16, (2), 292–298
Double-layer Cr/Pt thin films were deposited by pulsed laser deposition at room temperature to 600°C, both on crystalline (Si and MgO) and on amorphous (SiO2) substrates. Epitaxial films with a very good texture and a very smooth surface were obtained. With the excimer laser at an energy fluence of 5 J cm−2, the Pt/Cr multilayer shows a high crystalline quality independent of deposition temperature.
Ballistic Transport in Metallic Nanotubes with Reliable Pd Ohmic Contacts
D. MANN, A. JAVEY, J. KONG, Q. WANG and H. DAI, Nano Lett., 2003, 3, (11), 1541–1544
Contacting metallic single-walled C nanotubes by Pd gave highly reproducible ohmic contacts, which were used for an examination of ballistic transport in metallic nanotubes. The Pd ohmic contacts were more reliable than previously used Ti ohmic contacts. Pt gave non-ohmic contacts to metallic nanotubes. The length of the nanotube under the metal contact area is electrically turned off; transport occurs from metal to nanotube at the edge of the contacts.
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