Characterization of Acrylic Hydrogels by Open Circuit Potential Monitoring

Wilburn, Jeremy P.; Ciobanu, Mădălina; Löwy, Daniel A.

doi:10.1023/b:jach.0000031165.06422.b5

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…It has been proven as a sensitive and effective measure for monitoring spontaneous phenomena at zero current occurring at the electrode/solution interface, e.g., metal corrosion, 26,27 electroless deposition of Ag, 28 adsorption, 29 and absorption 30,31 of neutral species and ions onto metal surfaces, and chemical stability of acrylic hydrogels. 32 Although the use of ZMEs in contact with an electrolytic solution, 12,19 in which ionic exchange phenomena take place, has spread in the last two decades, to our knowledge, there are no reports on OCP measurements in these systems. Therefore, temporary follow-up of the open-circuit potential (OCP-t) of the ZME/electrolytic solution interface could be a sensitive means for a better understanding of the behavior of electrochemical measurements with regard to ionic exchange dynamics.…”

Section: Resultsmentioning

confidence: 99%

“…The open-circuit potential (OCP) is a measurement without a net current flow through the external circuit of the electrochemical cell. It has been proven as a sensitive and effective measure for monitoring spontaneous phenomena at zero current occurring at the electrode/solution interface, e.g., metal corrosion, , electroless deposition of Ag, adsorption, and absorption , of neutral species and ions onto metal surfaces, and chemical stability of acrylic hydrogels . Although the use of ZMEs in contact with an electrolytic solution, , in which ionic exchange phenomena take place, has spread in the last two decades, to our knowledge, there are no reports on OCP measurements in these systems.…”

Section: Resultsmentioning

confidence: 99%

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Influence of the Cation Na/Ca/Ag Ratio on the Ion Exchange Rate in Zeolite A-Modified Carbon Paste Electrodes

2008

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In contrast to previous electrochemical studies of silver-ion-exchanged zeolite-modified electrodes (Ag + sZMEs), in which only two different compensating monocations in the zeolite have been used, in this work is presented a more complicated case of zeolite A containing three cation types, one electroactive soft cation and two nonelectroactive hard cocations: Ag + , Na + , and Ca 2+ , respectively. Na 2 Ca 4 Ag 2 sA, Na 2 Ca 3 Ag 4 sA, and Na 2 Ag 10 sA were obtained by ion exchange from the commercial sodium form of Lynde type-A (Na 12 sA). It was checked by 27 Al and 29 Si MAS NMR and X-ray diffraction (XRD) that no dealumination or loss of crystallinity occurred during the ion-exchange procedure. The exchanged zeolites were used to prepare zeolite-modified carbon paste electrodes (ZMCPEs). An alternative access to diffusion phenomena was achieved by a combination of open-circuit potential (OCP) and cyclic voltammetry (CV) measurements. Both techniques were performed in aqueous electrolytic medium 0.1 M NaNO 3 , both quiescent and disturbed. This novel experimental route was applied to investigate the influence of the nature and content of cations in the ion-exchange rate of AgCaNasA ZMCPEs. At open circuit, the potential shifts are associated, for the first time, with the flux of cations from the zeolite framework to the electrode/solution interface. Voltammetric behavior of ZMCPEs are mainly ascribed to interactions and stabilization of extra-framework cations, which is determined by the nature of the exchange sites inside the cages and cavities. A mechanism of extrazeolitic charge transfer in CV is clear in scan potentials performed subsequently to the first one. However, at short time periods of immersion electrode, in the first cycle of electrical perturbation, the intrazeolitic character of the electrochemical processes is not discarded. In this way, the ion exchange rate decreases as the amount of divalent cation, Ca 2+ , increases. This is due to the strong interaction of the divalent cation with water molecules and with the framework. Besides, cation diffusion is modified by the presence of silicon oil binder in the carbon paste.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Influence of the Cation Na/Ca/Ag Ratio on the Ion Exchange Rate in Zeolite A-Modified Carbon Paste Electrodes

2008

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“…On the other hand, various non-silicon-based (e.g. conventional glass tube-based and PDMS-based) miniaturized reference electrodes (MREs) have been continuously developed in the last decade and performed very good electrochemical characteristics [9][10][11][12][13][14][15][16][17]. The physical size of MREs is about tenfold more than that of JlREs and their fabrication processes are not compatible with the silicon-based microfabrication technology, which limits their integration with electronic circuits and the development of system-on-a-chip (SOC).…”

Section: Introductionmentioning

confidence: 99%

Study on wafer-level packaging and electrochemical characterization of planar AgCl micro reference electrode

Huang

Hsieh

Chu

2009

2009 IEEE 3rd International Conference on Nano/Molecular Medicine and Engineering

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This study proposes a novel chip-level packaged planar Ti/Pd/AglAgCIIKCI-gel micro reference electrode for the electrochemical and biomedical sensing applications. The miniaturized reference electrode is constructed by two wafers ("Ti/Pd/AglAgCI quasi reference electrode wafer" and "KCI-gel cap sealing wafer") and with a total dimension of only 9 mm (L) x 6 mm (W) x 1 mm (H). hundredfold less than the commercial Ag/AgCI reference electrode (OD = 12 mm). Many excellent characteristics were demonstrated by the optimized encapsulated solid-state micro reference electrode, including a very stable cell potential (5 mV drift voltage in 30,000 s), an approximately zero offset-voltage, a very low impedance « 1.50 k!!) and phase shift «8.98 0) at normal operation frequency range (0-1 kHz), and a low electro-chemical noise spectrum.

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“…It has been applied in monitoring the corrosion behavior of metal, [1][2][3] hydrogen absorption in Pd electrodes, 4 oxygen, 5 carbon monoxide, 6 adsorption in Pt/Pd electrode, and characterization of acrylic hydrogels. 7 Our group also reports its application in electroless deposition of Ag. 8 However, the methodology of OCP-t is still undeveloped.…”

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confidence: 99%

The Termodynamic Model of Open-Circuit Potential for Electroless Deposition of Ni on Silicon

Chang

et al. 2006

J. Electrochem. Soc.

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This investigation first proposed that open-circuit potential vs time ͑OCP-t͒ is a novel nonlinear potential step controlled by redox reaction and nucleation. A novel thermodynamic model of OCP-t is obtained for electroless deposition of Ni on Pd-activated p-type silicon͑100͒. Thermodynamic transient properties such as capacity of double layer C, surface charge density q, interfacial tension ␥, and resistance of chemical reaction Rr are calculated. Results show that the variation of OCP is dependant on the interfacial double layer. The breakdown and rearrangement of the double layer causes surface charge density step, which triggers momentary nucleation of Ni on the substrate. Results also show that reductant pulses would be an effective way to speed nuclei growth.Open-circuit potential vs time ͑OCP-t͒ has been proved a sensitive and effective technique for sensing transient mixed potential at the interface of solid/solution. It has been applied in monitoring the corrosion behavior of metal, 1-3 hydrogen absorption in Pd electrodes, 4 oxygen, 5 carbon monoxide, 6 adsorption in Pt/Pd electrode, and characterization of acrylic hydrogels. 7 Our group also reports its application in electroless deposition of Ag. 8 However, the methodology of OCP-t is still undeveloped. Few papers on the mathematic model of OCP-t are reported. In this work, a novel thermodynamic model of OCP-t is used to propose for electroless deposition. We believe that it would be helpful to understand the process of electroless deposition and develop further applications of OCP-t.Electroless deposition of metal films on silicon such as aluminum, 9 copper, 9-11 silver, 12,13 gold, 14 nickel, 15,16 NiP alloy, 17 NiB alloy, 18 and CuNi alloy 19 have been investigated. The nucleation and reaction mechanisms 16-20 have also been studied. However, the transient information of electroless deposition is still blurry and needs to find a sensitive technique to describe it. OCP-t is an ideal option for this purpose because it can record transient potential of electroless deposition effectively. 8 Other transient techniques controlled by outer circuits such as conventional potential step and current step make it difficult to acquire actual information of electroless deposition.During the electroless deposition process, there are six processes occurring on the surface of samples, which include: ͑i͒ mass transport of ions, ͑ii͒ migration of ions, ͑iii͒ charge or discharge of double layer, ͑iv͒ adsorption or desorption of ions, ͑v͒ chemical reaction, and ͑vi͒ nucleation on the substrate. 21 In this experiment, the mass transport and migration of ions can be ignored because of agitating strongly. NiSO 4 solution and NH 2 NH 2 reductant are selected because their reactions are clear. Amperometric i-t is used to acquire transient current of electroless deposition. Ni film and Pd seed layer are characterized by atomic force microscope ͑AFM͒ and differential pulse voltammetry ͑DPV͒. ExperimentalInstruments and software.-AFM ͑Explorer, Veeco Co., USA͒ in contact mode,...

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Characterization of Acrylic Hydrogels by Open Circuit Potential Monitoring

Cited by 10 publications

References 17 publications

Influence of the Cation Na/Ca/Ag Ratio on the Ion Exchange Rate in Zeolite A-Modified Carbon Paste Electrodes

Influence of the Cation Na/Ca/Ag Ratio on the Ion Exchange Rate in Zeolite A-Modified Carbon Paste Electrodes

Study on wafer-level packaging and electrochemical characterization of planar AgCl micro reference electrode

The Termodynamic Model of Open-Circuit Potential for Electroless Deposition of Ni on Silicon

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