11113-88-5Relevant articles and documents
Silver mediation of Fe(VI) charge transfer: Activation of the K2FeO4 super-iron cathode
Licht, Stuart,Naschitz, Vera,Ghosh, Susanta
, p. 5947 - 5955 (2002)
An unexpectedly large Ag(II) mediation of Fe(VI) redox chemistry improves alkaline Fe(VI) cathodic charge transfer. Combined with a Zn anode, this results in a cell with 3- to 5-fold higher energy capacity than the conventional high-power Zn/MnO2 alkaline battery, and twice that previously observed for Zn/BaFeO4. Both experimental results and a model of this phenomenon are presented. The Ag(II) salt may be introduced as a simple composite of AgO with the Fe(VI) salt. The Fe(VI) super-iron salt K2FeO4 has a high 3e- intrinsic charge capacity (406 mA/g), and is more environmentally benign than the Fe(VI) salt BaFeO4, but had exhibited comparatively poor charge transfer. Successful AgO cathodic activation of both K2FeO4 and BaFeO4 redox chemistry are presented. Various other K2FeO4 activators are also studied. An observed interaction of Fe(VI) with Mn(VII/VI) can improve charge efficiency of a K2FeO4 composite with KMnO4 or BaMnO4, albeit not to the extent observed in an K2FeO4/AgO composite cathode. The extent of an activation effect of oxides, hydroxides, and titanates salts, as well as KMnO4, BaMnO4, AgMnO4, and fluorinated graphites, on the cathodic discharge of K2FeO4 are probed.
AgCuO2 as a novel bifunctional electrocatalyst for overall water splitting in alkaline media
Kamali Moghaddam, Saeideh,Seyed Ahmadian, Seyed Masoud,Haghighi, Behzad
, p. 4633 - 4639 (2019)
Nanostructured transition metal oxides are among the most prevalent catalysts for the water-splitting process. Herein, AgCuO2 nanoparticles (NPs) are introduced as a novel bifunctional electrocatalyst for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media. The catalyst, AgCuO2 NPs, exhibited excellent electrocatalytic activity together with a low overpotential for the overall water-splitting process. The AgCuO2 exhibits excellent electrocatalytic activity with a low onset overpotential of 29 mV for the HER and the onset overpotential of 360 mV for the OER, with superior long-term stability in 1.0 M KOH. The catalyst delivered 10 and 100 mA cm?2 at extremely low overpotentials of 42 and 47 mV for the HER and 10 mA cm?2 at an overpotential of 388 mV for the OER. This work suggests an important reference toward the use of novel bimetallic oxides as highly active and stable bifunctional electrocatalysts for high-performance water splitting.
Room temperature solid-state transformation from Ag2Cu 2O3 to Ag2Cu2O4 by ozone oxidation
Munoz-Rojas,Fraxedas,Gomez-Romero,Casan-Pastor
, p. 295 - 305 (2005)
The mixed silver-copper oxide, Ag2Cu2O4 has been previously synthesized by electrochemical oxidation of suspensions of the precursor Ag2Cu2O3 and also by direct oxidation/coprecipitation of
The millimeter wave spectrum of silver monoxide, AgO
Steimle,Tanimoto,Namiki,Saito
, p. 7616 - 7622 (1998)
The pure rotational spectra of 107AgO and 109AgO were recorded in the 117-380 GHz spectral region using a dc-sputtering absorption cell. The 107Ag(I=1/2) and 109Ag(I=1/2) magnetic hyperfine parameters are interpreted in terms of plausible electronic configuration contributions to the X 2Πi state. It is shown that the determined unusual sign of the Λ-doubling and Fermi contact parameters implies that the X 2Πi state is dominated by a three open shell configuration. A comparison with isovalent CuO is made.
Stabilized alkaline Fe(VI) charge transfer
Licht, Stuart,Yu, Xingwen,Wang, Yufei
, p. A1-A7 (2008)
Superiron cathodes, consisting of unusual Fe(VI) particles, are substantially stabilized with a low-level zirconia coating, which improves the experimental energy storage capacity of alkaline superiron batteries. Fe(VI) cathodes sustain three-electron alkaline reduction at a single, energetic [0.60 V vs standard hydrogen electrode (SHE)] potential. Superiron cathode salts such as K2 FeO4 and Cs2 FeO4 are stable in the solid state but tend to be passivated in alkaline electrolyte due to the formation of an Fe(III) overlayer. A zirconia coating is derived from ZrCl4 through an organic medium by the conversion of ZrCl4 to ZrO2. The zirconia coating shuttles hydroxide through to the interior cathode material, sustains a high rate of alkaline cathode charge transfer in the redox reduction of Fe(VI) to Fe(III) redox reduction, and inhibits Fe(III) passivation. The zirconia coating effectively enhances the stability of these superiron cathodes. However, for an Fe(VI) salt, which is not stable in the solid state, such as BaFeO2, an applied zirconia coating is not observed to stabilize alkaline cathodic charge transfer. Small particle and solid KOH and AgO additives each are observed to improve Fe(VI) cathodic charge transfer and enhance accessible Fe(VI) gravimetric capacity.
Thermal decomposition of metal nitrates in air and hydrogen environments
Yuvaraj, Shanmugam,Lin, Fan-Yuan,Chang, Tsong-Huei,Yeh, Chuin-Tih
, p. 1044 - 1047 (2003)
The decomposition of metal nitrates in air has been systematically studied by thermogravimetry. Observed temperature of decomposition (Td) have been inversely correlated to the charge densities (CD) of the metal cations. Due to a back-donation of electronic cloud from the nitrate to an unfilled d-orbital of transition and noble metals, their nitrates generally exhibited lower TdS ( 850 K). The thermal stability/reducibility of metal nitrates in an hydrogen atmosphere has also been studied by temperature-programmed reduction (TPR). Observed reduction temperatures (Tr) for nitrates of the base metals and the noble metals are lower than their Td, i.e., Tr d. The lowering of Tr might be attributed to a spillover of hydrogen to a nitrate moiety through heterolytic (ionic) and homolytic (atomic) dissociation of hydrogen on the respective base and noble metals. The stoichiometry of hydrogen consumption, quantitatively measured from TPR, varied with the group of metal cations. According to the stoichiometry, the end product in the TPR reduction was NH3 (NH2/NNO3-a??4.4) and N2 (NH2/NNO3-a??2.4) for nitrates of the noble and base metals, respectively. The Trs for nitrates of the transition metals are often a??20 K higher than their Tds, and the ratio NH(2)/NNO3- varies widely between 0.7 and 3.2. Their reduction may be triggered by thermal decomposition.
The super-iron boride battery
Licht, Stuart,Yu, Xingwen,Wang, Yufei,Wu, Huiming
, p. A297-A303 (2008)
A high-capacity alkaline redox storage chemistry is explored based on an environmentally benign zirconia-stabilized Fe6+ B2- chemistry. This super-iron boride battery sustains an electrochemical potential matched to the pervasive, conventional MnO2 -Zn battery chemistry, but with a much higher electrochemical storage capacity. Whereas a conventional alkaline battery pairs the 2 e- zinc anode with a 1 e- MnO2 cathode, the new alkaline cell couples an 11 e- boride anode, such as VB2, with a 3 e- storage hexavalent iron cathode. The cell has an open circuit and discharge potential comparable to the conventional, commercial alkaline battery. Based on VB2 (72.6 g mol-1) and the Fe(VI) salt K2 FeO4 (198.0 g mol-1), the super-iron boride cell has an 11 Faraday theoretical capacity of 369 mAh g-1. Added AgO mediates and further facilitates the 3 e- K2 FeO4 reductive charge transfer, and we demonstrate for super-iron boride that over 300 mAh g-1 is approached experimentally, which is substantially higher than the conventional Zn MnO2 alkaline battery with an experimental capacity (to 0.8 V) of 160 mAh g-1 and a theoretical capacity of 224 mAh g-1.
Differences in thermal decomposition of Ag(I), Mn(II), Fe(II) and Fe(III) complexes of cyclic dithiocarbamates
Bernal, Cláudia,Neves, Eduardo Almeida,Cavalheiro, éder T.G.
, p. 49 - 55 (2001)
The thermal decomposition of pyrrolidinedithiocarbamate (Pyr) and piperidinedithiocarbamate (Pip) complexes of Ag(I), Mn(II), Fe(II) and Fe(III) have been investigated by thermogravimetry and differential scanning calorimetry. The decomposition intermedia
Low-activation solid-state syntheses by reducing transport lengths to atomic scales as demonstrated by case studies on AgNO3 and AgO
Fischer, Dieter,Jansen, Martin
, p. 3488 - 3489 (2002)
We have studied solid-state reactions of educt mixtures of elements in an atomic dispersion. The reduced transport distances allow for extremely low activated reactions. This has been demonstrated by case studies on AgNO3 and AgO, which form an
Evidence for an Ag4O3 Phase of Silver Oxide
Mansour, A. N.
, p. 1006 - 1010 (1990)
The structure of chemically and electrochemically prepared AgO materials was investigated by extended X-ray absorption fine structure (EXAFS) spectroscopy.It was found that chemically prepared (CP) AgO is composed of Ag(+) and Ag(3+) ions coordinated with two oxygens at 2.13 Angstroem and four oxygens at 1.99 Angstroem, respectively.For electrochemically prepared (EP) AgO, the Ag(+) ions are also coordinated with two oxygens at a distance of 2.13 Angstroem.However, the coordination number for the Ag(3+) ions varies from 2.8 to 3.5 oxygens without any significant change in the coordination distance of 1.99 Angstroem.That is, EP AgO is really AgO1-δ, where δ is the degree of oxygen deficiency near the Ag(3+) ions.The magnitude of δ can be as large as 0.29 +/- 0.05 and is a strong function of preparation procedures.The EXAFS results reveal that a phase of silver oxide, Ag4O3, is formed electrochemically.The EXAFS results also suggest that the electrochemical oxidation of Ag or Ag2O to AgO proceeds via the formation of Ag4O3 as an intermediate step.
