1173018-52-4Relevant articles and documents
PHOTOINDUCED OXYGEN FORMATION AND SILVER-METAL DEPOSITION IN AQUEOUS SOLUTIONS OF VARIOUS SILVER SALTS BY SUSPENDED TITANIUM DIOXIDE POWDER
Nishimoto, Sei-Ichi,Ohtani, Bunsho,Kajiwara, Hiroshi,Kagiya, Tsutomu
, p. 2685 - 2694 (1983)
The photochemical reaction of Ar-purged aqueous solutions containing various silver salts and TiO2 powder in suspension has been studied at room temperature.Photoirradiation (λex was comparable to that of the anatase A)>.The molar ratio of deposited Ag metal to liberated O2, which was independent of the reaction rate, was equal to ca. 5 except for the case of TiO2(A)/AgClO4.The pH of the reaction mixture decreased with irradiation time, resulting in deactivation of the TiO2.Although O2 formation and Ag-metal deposition did not occur at pH 2, the photosensitizing activity of the TiO2 powder was recovered by the addition of NaOH.The addition of propan-2-ol to the deactivated acidic suspension of TiO2 was also effective for Ag-metal deposition but not for O2 formation.
Kinetic study of the reaction of HO2 with ozone
Sinha, Amitabha,Lovejoy, Edward R.,Howard, Carleton J.
, p. 2122 - 2128 (1987)
The reaction HO2 + O3 -> OH + 2O2 has been studied using a discharge-flow system with laser magnetic resonance detection.The rate constant for the reaction was determined directly by monitoring the first-order decay of isotopically labeled H18O2 in excess 16O3.The data give a curved Arrhenius plot over the temperature range.A more representative fit is obtained with a three parameter expression: .The error limits are the 95percent confidence limits on the coefficients while the accuracy of the measurements is estimated to be about +/-20percent at each temperature.An analysis of the OH radical product indicates that 16OH is formed predominately (75+/-10)percent.The scrambling reactions H18O2 + 16O3 -> H16O2 + 18O18O16O (1c) and H18O2 + 16O2 -> H16O2 + 18O2 (8) were also examined and found to be slow.Their rate constants are k1c -17 cm3s-1 at 297 and 333 K and k8 -17 cm3 s-1 at 297 and 413 K.
Characterization and activity analysis of catalytic water oxidation induced by hybridization of [(OH2)(terpy)Mn(μ-O)2Mn(terpy) (OH2)]3+ and clay compounds
Narita, Komei,Kuwabara, Takayuki,Sone, Koji,Shimizu, Ken-Ichi,Yagi, Masayuki
, p. 23107 - 23114 (2006)
Hybridization of [(OH2)(terpy)Mn(μ-O)2Mn(terpy) (OH2)]3+ (terpy = 2,2′:6′,2″- terpyridine) (1) and mica clay yielded catalytic dioxygen (O2) evolution from water using a CeIV oxidant. The reaction was characterized by various spectroscopic measurements and a kinetic analysis of O2 evolution. X-ray diffraction (XRD) data indicates the interlayer separation of mica changes upon intercalation of 1. The UV-vis diffuse reflectance (RD) and Mn K-edge X-ray absorption near-edge structure (XANES) data suggest that the oxidation state of the di-μ-oxo Mn2 core is MnIII-MnIV, but it is not intact. In aqueous solution, the reaction of 1 with a large excess CeIV oxidant led to decomposition of 1 to form MnO4- ion without O2 evolution, most possibly by its disproportionation. However, MnO4- formation is suppressed by adsorption of 1 on clay. The maximum turnover number for O2 evolution catalyzed by 1 adsorbed on mica and kaolin was 15 and 17, respectively, under the optimum conditions. The catalysis occurs in the interlayer space of mica or on the surface of kaolin, whereas MnO 4- formation occurs in the liquid phase, involving local adsorption equilibria of adsorbed 1 at the interface between the clay surface and the liquid phase. The analysis of O2 evolution activity showed that the catalysis requires cooperation of two equivalents of 1 adsorbed on clay. The second-order rate constant based on the concentration (mol g -1) of 1 per unit weight of clay was 2.7 ± 0.1 mol -1 s-1 g for mica, which is appreciably lower than that for kaolin (23.9 ± 0.4 mol-1 s-1 g). This difference can be explained by the localized adsorption of 1 on the surface for kaolin. However, the apparent turnover frequency ((kO2) app/s-1) of 1 on mica was 2.2 times greater than on kaolin when the same fractional loading is compared. The higher cation exchange capacity (CEC) of mica statistically affords a shorter distance between the anionic sites to which 1 is attracted electrostatically, making the cooperative interaction between adsorbed molecules of 1 easier than that on kaolin. The higher CEC is important not only for attaining a higher loading but also for the higher catalytic activity of adsorbed 1.
Cu2O as a photocatalyst for overall water splitting under visible light irradiation
Hara, Michikazu
, p. 357 - 358 (1998)
Photocatalytic decomposition of water into H2 and O2 on Cu2O under visible light irradiation is investigated; the photocatalytic water splitting on Cu2U powder proceeds without any noticeable decrease in the activity for more than 1900 h.
An IrSi oxide film as a highly active water-oxidation catalyst in acidic media
Tran, Viet-Ha,Yatabe, Takeshi,Matsumoto, Takahiro,Nakai, Hidetaka,Suzuki, Kazuharu,Enomoto, Takao,Hibino, Takashi,Kaneko, Kenji,Ogo, Seiji
, p. 12589 - 12592 (2015)
We report an acid-stable Si oxide-doped Ir oxide film (IrSi oxide film), made by metal organic chemical vapour deposition (MOCVD) of an IrV complex for electrochemical water-oxidation. This is a successful improvement of catalytic ability and stability depending upon the pH of Ir oxide by doping of Si oxide. The turnover frequency (TOF) of the electrochemical water-oxidation by the IrSi oxide film is the highest of any Si oxide-doped Ir oxide materials and higher even than that of Ir oxide in acidic media.
Efficient photocatalytic water oxidation catalyzed by polyoxometalate [Fe11(H2O)14(OH)2(W3O10)2(α-SbW9O33)6]27- based on abundant metals
Du, Xiaoqiang,Ding, Yong,Song, Fangyuan,Ma, Baochun,Zhao, Junwei,Song, Jie
, p. 13925 - 13928 (2015/09/07)
An eleven iron-containing nanoscale inorganic polyanionic oxide cluster was reported as the first example for exceptional photocatalytic water oxidation. Under optimal conditions, a remarkable turn-over number (TON) of 1815 ± 50 and a turn-over frequency (TOFinitial) of 6.3 s-1 over 1 were achieved for water oxidation.
CARS spectroscopy of O2() from the Hartley band photodissociation of O3: Dynamics of the dissociation
Valentini, James J.,Gerrity, Daniel P.,Phillips, David L.,Nieh, Jong-Chen,Tabor, Kevin D.
, p. 6745 - 6756 (2007/10/02)
(Received 29 December 1986; accepted 10 March 1987) Rotationally and vibrationally resolved CARS spectra of the O2() photofragment produced by the photodissociation of O3 at 17 wavelengths between 230 and 311 nm are reported.The spectra are taken under collision-free conditions, therefore, they reveal the nascent rotational and vibrational state distributions of the O2 () photofragment.At all photolysis wavelengths studied the vibrational distribution peaks very sharply at ν = 0, although all energetically allowed vibrational states are observed.The rotational state distributions are narrow, and peak typically at high J.The rotational distribution shifts to lower J as the photolysis wavelength increases.These observations imply vibrationally adiabatic, rotationally impulsive energy release in the dissociation.The shape and width of the rotational distributions can be completely accounted for by the spread in the 03 thermal rotation and zero-point vibration contributions to the O2 () photofragment angular momentum.The most striking observation about the O2 () photofragment quantum state distribution is an apparent propensity for even-J states.Experiments with 18O enriched ozone indicate that this propensity is observed only for16O16O, not for18O16O, and by implication not for 17O16O.We show that this is the consequence of a selective depletion of only odd-J rotational states of 16O16O ( ) by a curve crossing to O2(), but an equal depletion of both even-J and odd-Jrotational states of 18O16O and 17O16O( ) by the curve crossing.The odd-J selectivity for 16O16O is a consequence of the restriction of to only odd-J states, due to the requirement of even nuclear exchange symmetry for this homonuclear species with spin-zero nuclei.As a result of the different curve crossing behavior, the quantum yield for , is twice as great for 18O160 and 17O16O as it is for 16O16O, and this imposes a mass-independent isotopic fractionation in the photodissociation: the O2( ) fragments are depleted of 17O and 18O, while the O2 () fragments are enriched in these isotopes.
Ultrasonic Irradiation in the Presence of (18,18)O2: Isotope Exchange and Isotopic Distribution of H2O2
Fischer, Christian-H.,Hart, Edwin J.,Henglein, Arnim
, p. 1954 - 1956 (2007/10/02)
Water was irradiated by 300-kHz ultrasound under argon, oxygen-18, and mixtures of these two gases, and the isotopic distribution of O2 and H2O2 was determined.The consumption of (18,18)O2 was much faster than the formation of H2O2.All possible isotopic O2 and H2O2 formation occur through common intermadiates.A mechanism is proposed in which radical reactions in hot gas bubbles occur as in combustion chemistry and in which the isotopic identity of the radicals and atoms originally produced from (16)OH2 and (18,18)O2 is partly lost.The final products O2 and H2O2 are potulated to be formed in a cooler interfacial region.
