- The O-O Bonding and Hydrogen Storage in the Pyrite-type PtO2
-
We have synthesized pyrite-type PtO2 (py-PtO2) at 50-60 GPa and successfully recovered it at 1 bar. The observed O-O stretching vibration in Raman spectra provides direct evidence for inter-oxygen bonding in the structure. We also identified the O-H vibrations in py-PtO2 synthesized from the lowerature areas, indicating hydrogenation, py-PtO2Hx (x ≤ 1). Diffraction patterns are consistent with a range of degrees of hydrogenation controlled by temperature. We found that py-PtO2 has a high bulk modulus, 314 ± 4 GPa. The chemical behaviors found in py-PtO2 have implications for the hydrogen storage in materials with anion-anion bonding, and the geochemistry of oxygen, hydrogen, and transition metals in the deep planetary interiors.
- Chen, Huawei,Zhou, Shuxiang,Morgan, Dane,Prakapenka, Vitali,Greenberg, Eran,Leinenweber, Kurt,Shim, Sang-Heon
-
-
Read Online
- PLATINUM LOSSES DURING HIGH TEMPERATURE OXIDATION.
-
Platinum reacts with oxygen at high temperatures to form volatile oxides the evaporation of which considerably increases the platinum losses in oxygen-containing atmospheres compared with high vacuum conditions. The metal losses of polycrystalline platinum disks were determined in the pressure range 10** minus **1-10**5 Pa and at high temperatures (1300-1600 degree C) using a magnetic suspension balance. Marked temperature and pressure dependences were observed. The oxidation mechanism is discussed and the oxidation rates reported in the literature are reviewed.
- Jehn
-
-
Read Online
- A study of PtRuO2 catalysts thermally formed on titanium mesh for methanol oxidation
-
Platinum-based catalysts, for the electro-oxidation of methanol, have been made by thermal decomposition of chloride precursors onto titanium mesh. The catalysed electrodes were successfully operated in acidic methanol electrolytes. Electrochemical characterisation has been carried out using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic polarisations. A complete analysis of the electrochemical results showed that the preliminary performance of the catalysed titanium mesh was comparable to that achieved with carbon-supported PtRu catalysts. The catalysts formed on titanium mesh by thermal decomposition also exhibited dimensional stability. Catalysed titanium mesh therefore appears to be a promising alternative to carbon-supported catalysts for certain fuel cell applications.
- Yang,Allen,Scott,Christenson,Roy
-
-
Read Online
- Biochemical Characterization and Antimicrobial Activity against Some Human or Phyto-Pathogens of New Diazonium Heterocyclic Metal Complexes
-
String of vanadium (IV), zirconium (IV), palladium (II), platinum (IV) and uranium (VI) chelates of 2-cyano-2-[(2-nitrophenyl)hydrazono]thioacetamide (Cnphta) were prepared and characterized by physicochemical, spectroscopic and thermal analyses. The form
- El-Attar, Mohamed S.,Elshafie, Hazem S.,Sadeek, Sadeek A.,El-Farargy, Ahmed F.,El-Desoky, Sameh I.,El-Shwiniy, Walaa H.,Camele, Ippolito
-
-
- Precious metal-molecular oxygen complexes: Neon matrix infrared spectra and density functional calculations for M(O2), M(O2)2 (M = Pd, Pt, Ag, Au)
-
Laser-ablated palladium, platinum, silver, and gold atoms react with molecular oxygen in excess neon during condensation at 4 K. Reaction products, M-(η2-OO), M-(η2-OO)2 (M = Pd, Pt), PtO, PtO2, AuO2,
- Wang, Xuefeng,Andrews, Lester
-
p. 5812 - 5822
(2007/10/03)
-
- Metal Oxides as Heterogenous Catalysts for Oxygen Evolution under Photochemical Conditions
-
Metal oxides in the form of dispersed powders, have been tested as potential catalysts for the four-electron oxidation of water to O2 under photochemical conditions.The most efficient catalysts were found to be IrO3, Co3O4, RuO2, NiCo2O4, Rh2O3 and Mn2O3 and, in particular, high activity was observed with IrO2.Comparison of the oxide structure wit its observed rate of O2 generation under standard conditions has allowed formulation of a few general raquisites for an effective catalyst.Samples of iridium oxide deposited onto the surface of a second (inert) oxide were tested for their O2-evolving capability.The efficiency of the system depended markedly upon the nature of the support.Materials that favour formation of small deposits of iridium oxide (e.g.ZnO, MgO, TiO2) are the best supports, whilst O2 production is almost completely inhibited with acidic supports.Many metal oxides can be prepared in the form of hydrates of variable compositin.These materials also function as O2-evolving catalysts, the efficiency of the process depending upon any thermal pretreatment.This finding is explained in terms of changes in structure and composition of the oxide that occur upon heating.
- Harriman, Anthony,Pickering, Ingrid J.,Thomas, John M.,Christensen, Paul A.
-
p. 2795 - 2806
(2007/10/02)
-
