共查询到20条相似文献,搜索用时 15 毫秒
1.
《Electrochemistry communications》2000,2(1):48-50
A novel method is employed for the simultaneous determination of both the calibration constant of an electrochemical quartz crystal microbalance (EQCM) and the active surface area of a polycrystalline gold electrode. A gold electrode is immersed into a 1 mM KI/1 M H2SO4 solution and on which forms a neutral monolayer. The adsorbed iodine can then be completely oxidized into IO3−. The active surface area of a gold electrode can be obtained from the net electrolytic charge of the oxidation process, and the calibration constant in the EQCM can be calculated from the corresponding frequency shift. The result shows that this method is simple, convenient and valid. 相似文献
2.
3.
The response of the electrochemical quartz crystal microbalance (EQCM) in dilute NaClO4 solutions was studied with gold and iron electrodes during a stepwise increase of the perchlorate concentration. In the range from 10−4 M to 7.8×10−2 M, the quartz resonant frequency of the 10 MHz AT cut crystals increased by about 700 Hz, indicating a mass loss on the electrode. A model was developed in which the diffuse double layer and the oscillating bulk electrolyte layer, characterised by the velocity decay length of the damped shear wave in solution, are treated as two independent, superimposed sheets. By assuming a characteristic thickness of the diffuse double layer according to the Gouy–Chapman theory and by treating the diffuse double layer as a rigid sheet, the measured mass loss could be simulated qualitatively. The viscosity changes in the diffuse double layer as well as in the sensed electrolyte bulk layer were found to be negligible in the concentration range investigated. In dilute solutions, the frequency shift following a concentration change is entirely due to thinning of the diffuse double layer with increasing concentration. The results demonstrate the importance of diffuse double layer effects for EQCM measurements in dilute electrolytes. 相似文献
4.
Laura Pigani Renato Seeber Fabio Terzi Chiara Zanardi 《Journal of Electroanalytical Chemistry》2004,570(2):235-242
Electrogenerated deposits of poly[4,4′-bis(butylsulphanyl)-2,2′-bithiophene] have been characterised in the presence of different supporting electrolytes, by coupling current (charge) to microgravimetric measurements from the electrochemical quartz crystal microbalance (EQCM). The simultaneous collection of voltammetric measurements and of data relative to mass changes shows the influence exerted by the nature of the supporting electrolyte on the charge-discharge steps of both p- and n-doping processes. Interestingly, the microgravimetric data collected corresponding to the pre-peaks of both doping processes suggest the occurrence of two opposite motions of ions (ingress into and exit out from the polymer) in the relevant potential region, giving a contribution to the study of the `residual charge' phenomenon. 相似文献
5.
A new method for the quantitative determination of palladium(II) by the electrochemical quartz crystal microbalance (EQCM) technique has been developed. Using a bare carbon-coated quartz crystal, Pd(II) ions are directly deposited from aqueous solution as palladium metal onto the crystal surface, and the Pd(II) concentration is determined with a detection limit of 0.0156 mM, or 1.66 ppm. No complexing agent or preconcentration of palladium is required for the analysis. The palladium is stripped from the crystal through its electrochemical oxidation, regenerating the crystal for subsequent multi-cycle palladium analyses. A conventional gold-coated quartz crystal was incapable of carrying out the same measurements. The EQCM technique presented is simple, sensitive, and reproducible for the detection of this widely used precious metal. 相似文献
6.
Voltammetry and electrochemical quartz crystal microbalance (EQCM) studies of MnO2 films electrodeposited in acidic media at 85°C show the existence of matter exchange during repeated electrochemical reduction and oxidation in 1 M KOH solution. Usually, these reactions are written without mentioning the exchange of matter. The following are observed: a reversible exchange involving water between the crystal lattice and the solution within each successive sweep potential cycle; an irreversible mass loss caused by low dissolution and slow diffusion of Mn(III) and Mn(II) solubilized species; an irreversible large mass gain during the first cycle due to additional hydration of the material. 相似文献
7.
《Electrochemistry communications》2000,2(6):412-416
The electrochemical quartz crystal microbalance (EQCM) was used to study adsorption/desorption of perchlorate and perrhenate ions on a bare polycrystalline gold electrode. An electrode mass change in perrhenate solution was about double that of perchlorate. The equivalent mass of adsorbed anions (about 260 and 120 g F−1 respectively) suggests adsorption of perchlorate and perrhenate anions on a polycrystalline gold electrode in the double-layer region. Water molecules are partially expelled from the gold surface during the initial stages of anion adsorption. The water loss is about three times larger for perrhenate compared to perchlorate due to the bigger ionic radius (volume) of the perrhenate anion. 相似文献
8.
Mariusz Łukaszewski Hanna Siwek Andrzej Czerwiński 《Journal of Solid State Electrochemistry》2010,14(7):1279-1292
The analysis of the electrochemical quartz crystal microbalance (EQCM) signal is presented for the case of oxidation of carbon
oxides adsorption products on Pt, Rh, and their alloys. It is demonstrated that the EQCM response can be roughly approximated
by the mass balance involving adsorption/desorption of various species (carbon oxides, oxygen, anions, and water molecules)
and metal dissolution. The results obtained by the EQCM are in good agreement with the electrochemical data and confirm the
domination of CO radicals among the products of CO2 reduction and CO adsorption on Pt-rich electrodes. In the case of Rh-rich electrodes, the existence of additional species
(CHO or COH), more reduced than CO, is suggested. 相似文献
9.
Heidi M. French Mark J. Henderson A. Robert Hillman Eric Vieil 《Journal of Electroanalytical Chemistry》2001,500(1-2)
A combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) instrument was used to monitor the mobile species transfers associated with the redox processes of thin (Γ100–150 nmol cm−2) α- and β-nickel hydroxide films exposed to aqueous LiOH solution. A comparison of the measured PBD signal with the predicted PBD profiles, calculated by temporal convolution analysis of the current and mass responses, enabled the contributions to redox switching of anion (OH−) and solvent (H2O) transfers to be discriminated quantitatively. The responses from the combined instrument are reconciled in terms of H+ deintercalation/intercalation within the nickel hydroxide structure as OH− ions enter/exit the film. Hydroxide ion movement is associated with a counterflux of water. Thin nickel hydroxide films show a gradual α→β phase transformation with continuous voltammetric cycling, especially when the films are exposed to high concentrations of electrolyte. α-Films are characterised by OH− transfers that dominate the H+ and H2O movements; β-films are characterised by an increased participation of water and protons to the exchange dynamics. 相似文献
10.
《Electrochemistry communications》2003,5(4):297-300
Electrochemical quartz crystal microbalance (EQCM) has been employed to study the potential oscillatory mechanism for the IO3− reduction accompanying periodic hydrogen evolution. The new experimental results that were obtained by in situ EQCM monitoring clearly demonstrate the all key steps involved in the oscillation: the diffusion-limited depletion of IO3− by reduction, the formation, growth and departure of hydrogen bubbles on the surface, and the convection-induced replenishment of IO3− by the hydrogen evolution. In addition to the frequency response to the surface mass change as reported in the literature, our study first shows that simultaneous frequency responses to the changes of density and viscosity in the diffusion layer during the oscillation can also provide meaningful and even decisive information on the oscillatory mechanism for the oscillators involving the coupling of electrochemical reactions with diffusion and convection mass transfer. 相似文献
11.
Li Zhao Bai-Shuang Chen Jia-Lin Zhang Dian-Long Wang 《Journal of Solid State Electrochemistry》2012,16(6):2079-2084
A solid film was prepared by electrodepositing on a gold-film-coated quartz crystal electrode in Na2FeO4 solution, and characterized in 1?M LiClO4/propylene carbonate (PC) + 1, 2-dimethoxyethane (DME; 1:1 by volume) electrolyte using electrochemical quartz crystal microbalance (EQCM). The EQCM experimental and X-ray photoelectron spectroscopy results indicate that the composition of the electrodeposited solid film prepared in the potential range of 0.18 to ?0.57?V vs. Ag/AgCl is FeOOH; and almost 1?mol lithium ions can be intercalated into and then extracted from 1?mol FeOOH film during discharge/charge process in 1?M LiClO4/PC + DME electrolyte. The discharge/charge experiment indicates that the specific capacity of FeOOH film stabilizes at a value close to its theoretical specific capacity after 20 cycles, and FeOOH film maintains a specific capacity of about 300?mAh?g?1 at the end of 170 cycles. It is therefore concluded that the FeOOH film has a good electrochemical cycle ability in 1?M LiClO4/PC + DME electrolyte. 相似文献
12.
The adsorption behaviors of two organic molecules, benzoic acid (BA) and 2-butyne-1,4-diol (BD), on metal electrodes have been studied using an electrochemical quartz crystal microbalance (EQCM) combined with the cyclic voltammetry technique. In the range of potentials studied, BA molecules were adsorbed onto an electrodeposited gold electrode with a saturation concentration of 5.0 × 1014 molecules/cm2. It was found that the Frumkin isotherm model was most suitable to depict the electrosorption behavior. The isotherm parameters by nonlinear fitting, which agreed with the literature values, implied BA was chemisorbed on the gold surface. For BD on an electrodeposited nickel electrode, the equivalent molar mass of the reaction species was calculated on the basis of the voltammetry curve and mass curve, which were obtained simultaneously during the potential scan. The analysis of EQCM data for the electrosorption of BD on gold and nickel electrodes showed an irreversible characteristic; the latter effectively inhibited the hydrogen evolution reaction. 相似文献
13.
《Electroanalysis》2005,17(18):1601-1608
Metallopolymer films have important applications in electrochemical catalysis. The alternate electrostatic layer‐by‐layer method was used to assemble films of [Ru(bpy)2(PVP)10Cl]Cl (denoted as ClRu‐PVP) and [Os(bpy)2(PVP)10Cl]Cl (ClOs‐PVP) metallopolymers onto pyrolytic graphite electrodes. Film thickness estimated by quartz crystal microbalance was 6–8 nm. The effects of pH, electrolyte species and concentration on the electrochemical properties of these electroactive polymers were studied using cyclic voltammetry (CV). Behavior in various electrolytes was compared. Also the mass changes within the ultra‐thin film during redox of Os2+/3+ were characterized by in situ electrochemical quartz crystal microbalance (EQCM). The results indicate rapid reversible electron transfer, and show that both ClRu‐PVP and ClOs‐PVP have compact surface structures while ClOs‐PVP is a little denser than ClRu‐PVP. Although hydrogen ions do not participate in the chemical reaction of either film, the movement of Na+ cation and water accompanies the redox process of ClOs‐PVP films. 相似文献
14.
M. C. Santos A. J. Terezo V. C. Fernandes E. C. Pereira L. O. S. Bulhões 《Journal of Solid State Electrochemistry》2005,9(2):91-95
An electrochemical quartz crystal microbalance (EQCM) study of RuO2 thin films, prepared by the sol-gel precursor method, is presented. The X-ray diffraction (XRD) analysis demonstrates that RuO2 films were crystallized in the rutile phase and scanning electron microscopy investigations indicated the formation of a smooth surface. Cyclic voltammetry and EQCM studies were performed simultaneously in order to investigate the charging processes of the RuO2 films in 0.1 M HClO4. The voltammetric and mass versus potential responses present three well-defined regions associated with the RuO2 redox couples. Based on these results and on the mass-charge relationships, the corresponding charging mechanisms are proposed. In the potential region governed by the Ru3+/Ru4+ redox couple, the mass-charge relation can be associated with the double-injection of protons and electrons. The other regions correspond to water release and oxyhydroxide species formation during charging. 相似文献
15.
Michel Keddam Dr. Nicolas Portail Dr. Dao Trinh Vincent Vivier Dr. 《Chemphyschem》2009,10(18):3175-3182
Scanning electrochemical microscopy (SECM) is a powerful technique for performing quantitative measurements at a local scale. This paper covers the development of combinations of SECM with electrochemical impedance spectroscopy (EIS) and electrochemical quartz crystal microbalance (EQCM). Basic aspects are described and potential applications reported by several research groups are covered. The unique advantages of the coupled techniques—with additional information being obtained from each coupling—are also discussed. 相似文献
16.
《Electrochemistry communications》1999,1(5):167-170
Gravimetric measurements during electrochemical redox switching of an Os-containing hydrogel film in contact with aqueous electrolyte have been obtained beyond the Sauerbrey rigid mass limit of the electrochemical quartz crystal microbalance (EQCM). For an acoustically non-rigid film the frequency-to-mass Sauerbrey relationship is not valid and the mass has been obtained from the experimental electroacoustic impedance data collected simultaneously with electrochemical experiments interpreted using Martin's viscoelastic model. 相似文献
17.
Christelle Gautier Olivier Alévêque Fawzia Seladji Marylène Dias Tony Breton Eric Levillain 《Electrochemistry communications》2010,12(1):79-82
Self assembled monolayers (SAMs) formed from TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) derivative thiols have been studied by electrochemical quartz crystal microbalance (EQCM) in both aqueous and non-aqueous solvents. The in situ study of the mass transport occurring during the oxidation of TEMPO provides evidence of a ion pair formation without incorporation of solvent in densely packed nitroxyl radical SAMs. For SAMs having a low nitroxyl radical surface coverage, the effect of mixed SAMs is evidenced and seems to avoid the solvent incorporation. 相似文献
18.
Ispas Adriana Bund Andreas Vrublevsky Igor 《Journal of Solid State Electrochemistry》2010,14(11):2121-2128
Current transients and mass variations in as-prepared and heat-treated anodic alumina films were measured during re-anodizing
by means of voltammetry and electrochemical quartz crystal microbalance (EQCM), respectively. Aluminum electrodes (100 nm)
on quartz crystals were prepared by thermal evaporation. Anodic alumina films were formed on the surface of Al electrodes
in aqueous solutions of oxalic (0.3 M) and phosphoric (0.6 M) acid in the potentiostatic regime. The EQCM experiments did
not detect an overshoot in the mass variation of the Al electrode during re-anodizing of heat-treated anodic alumina films.
The observed current overshoot in transients proved the presence of electrons and electron holes injected from the contacts
in the bulk of the oxide. This can be explained by the emergence of excess electrons in the barrier layer of the alumina films
due to a change in the mobility of the electrons. 相似文献
19.
An electrochemical quartz crystal microbalance (EQCM) is employed for monitoring the growth of poly(neutral red) films on
platinum in the electrolytic solution containing 5.0 mmol dm−3 neutral red, 0.3 mol dm−3 H2SO4, and 0.5 mol dm−3 Na2SO4. The in situ measurement of the frequency changes of the EQCM reveals that both the adsorption/desorption of neutral red
and the formation of poly(neutral red) film can be observed together with anion sorption/desorption during the redox transformation
of the polymer, and that the polymerization rate of neutral red increases slowly before the 11th cycle and then increases
quickly with increasing number of potential cycles.
Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 3, pp. 284–289.
The text was submitted by the authors in English. 相似文献
20.
S. I. Córdoba de Torresi A. N. Bassetto B. C. Trasferetti 《Journal of Solid State Electrochemistry》1998,2(1):24-29
The effect of thickness, an alkyl substituent in the ortho position and the chemical nature of the counterion on the absorption spectra of polyaniline films was studied. Previous work
performed using the electrochemical quartz crystal microbalance technique (EQCM) has shown a greater participation of anions
in the ionic exchange process when the thickness of the film is increased. This fact was attributed to morphological changes
leading to different densities of the polymer film, which was demonstrated by SEM experiments. Changes in absorption spectra
provoked by conformational changes due to the presence of a substituent and the effect of the chemical nature of the anions
are analyzed for Cl−, ClO4
− and p-toluene sulfonate (PTS−).
Received: 13 May 1997 / Accepted: 21 July 1997 相似文献