XPS Study of Counterion Incorporation into Poly(vinylferrocene)

Zeng, Xiangqun; Moon, Seong-Bae; Bruckenstein, Stanley; Hillman, A. Robert

doi:10.1021/ac971318l

Cited by 12 publications

(13 citation statements)

References 38 publications

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“…This suggests that the changes in the intensity of feature b depend on the nature of the counterion. It is conceivable that the origin of the increased intensity of feature b in the fluorinebased compounds is related to the strong electron accepting nature of the PF 6 Ϫ and BF 4 Ϫ anions from the surrounding carbon rings. 9,10 PF 6 Ϫ and BF 4 Ϫ form strong bonds with the carbon ring by accepting electrons of character.…”

Section: Resultsmentioning

confidence: 99%

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X-Ray Absorption Studies of Poly(vinylferrocene) Polymers for Anion Separation

Balasubramanian¹,

Giacomini²,

Lee³

et al. 2002

J. Electrochem. Soc.

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X-ray absorption spectroscopy ͑XAS͒ was used to study the electrochemical incorporation of perrhenate anion, from a 0.1 M NH 4 ReO 4 solution, into poly͑vinylferrocene͒ ͑PVFc͒ and a modified PVFc ͑a copolymer of 30% t-butyl acetylferrocene and 70% t-butyl divinyl ferrocene͒. The polymers were deposited on a carbon cloth current collector from a solution of the polymers in CH 2 Cl 2 . In situ XAS measurements were done at the Fe K edge on the reduced polymers and at 0.9 V vs. Ag/AgCl. Ex situ XAS was done at the Re L 3 edge after oxidation of the polymers at 0.9 V. The oxidized electrodes were washed in water to remove dissolved NH 4 ReO 4 in the electrode pores. XAS was done both on wet-washed electrodes and on electrodes that were dried. XAS showed that at 0.9 V the Fe was oxidized from a ferrocene to a ferrocenium moiety and the FeuC bond distance increased from 2.05 to 2.08 Å. Both the X-ray absorption near-edge spectroscopy and extended X-ray absorption fine structure ͑EXAFS͒ results are consistent with having Ͼ75% of the ferrocene moieties in the polymer oxidized at 0.9 V. The Fe K-edge EXAFS showed no direct indication of interaction of Fe with ReO 4Ϫ . At the Re L 3 edge the only indication of interaction of ReO 4 Ϫ with the polymers was a slight change in the XANES features.Many industrial contaminants exist as anions. These include high-priority pollutants such as chromate, pertechnetate, and nitrate ions. Technetium is an important and difficult pollutant in nuclear waste. Because of its half-life of 213,000 years, technetium ( 99 Tc) presents a long-term hazard for waste disposal. Much of the 99 Tc in the tank wastes is present as pertechnetate (TcO 4 Ϫ ), accounting for its high solubility and mobility in aqueous systems. Conventional sorbents such as commercial ion exchange resins can be used to extract TcO 4Ϫ . However chemical elution of the ion exchange resin generates unwanted secondary wastes. An attractive alternative is to use an electrically conducting polymer ͑e.g., polyvinyl ferrocene, PVFc͒ to separate technetium from nitrate in high-level liquid nuclear waste. Absorption and elution can be done electrochemically without the generation of secondary wastes. The work reported here involves the use of in situ X-ray absorption spectroscopy ͑XAS͒ to study the interaction of anions with conductive polymer poly͑vinyl-ferrocene͒ electrodes. XAS investigation on pure ferrocene and related compounds has been reported earlier by others. [1][2][3][4] In this study perrhenate salts were used as nonradioactive surrogates for pertechnetate. The chemistry and electrochemistry of rhenium and technetium are rather similar. 5 The incorporation of anions in poly͑vinylferrocene͒ ͑PVFc͒ has been extensively studied. This work has been summarized in recent publications. 6,7 Until now the most effective in situ tool has been the electrochemical quartz crystal microbalance ͑EQCM͒. The technique is very effective in studies of anion intercalation and cointercalation of solvent. 6,7 However, EQCM does not yield chem...

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Section: Resultsmentioning

confidence: 99%

“…This work has been summarized in recent publications. 6,7 Until now the most effective in situ tool has been the electrochemical quartz crystal microbalance ͑EQCM͒. The technique is very effective in studies of anion intercalation and cointercalation of solvent.…”

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confidence: 99%

X-Ray Absorption Studies of Poly(vinylferrocene) Polymers for Anion Separation

Balasubramanian¹,

Giacomini²,

Lee³

et al. 2002

J. Electrochem. Soc.

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“…However, there were two pairs of fitting peaks in the Fe 2p spectrum shown in Figure 4b, representing Fe 2+ and Fe 3+ due to the oxidation of the ferrocene compound during the preparation of Pd NPs. 38,39 The peaks at 337.7 and 342.9 eV could be ascribed to Pd 0 in the Pd NPs. The peaks at 339.4 and 344.7 eV correspond to the Pd 2+ elements, which come from the residual Pd precursors.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

In Situ Preparation of Composite Redox-Active Micelles Bearing Pd Nanoparticles for the Reduction of 4-Nitrophenol

2021

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Owing to the redox activity of the poly-(ferrocenylsilane)-based polymer, several noble metal nanoparticles can be successfully prepared. As reported herein, the in situ preparation of Pd nanoparticles was performed using a redoxa c t i v e p l a t f o r m o f p o l y -(ferrocenylmethylethylthiocarboxylpropylsilane) (PFC) micelles. PFC/Pd nanocomposites (NCs) with Pd nanoparticles uniformly dispersed at the surface of PFC nanospheres were obtained. The morphology of PFC/Pd NCs was further confirmed via highresolution transmission electron microscopy and X-ray photoelectron spectroscopy. Taking advantage of Pd nanoparticles, the PFC/ Pd NCs showed significant catalytic activity during the reduction process of 4-nitrophenol by sodium borohydride. Although PFC micelles themselves showed no catalytic activity, they promoted the catalytic behavior of Pd nanoparticles obviously by anchoring the Pd nanoparticles at their surface to avoid the aggregation and leaching of Pd nanoparticles. In all, PFC/Pd NCs exhibited great potential as a composite nanocatalyst. Moreover, the PFC micelle was found to be a desired platform for nanocatalysts.

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“…For self-assembled monolayers and electroprecipitated films containing Fc moieties, the effect of electrolytes and film densities on the redox behavior has been thoroughly investigated. ,,− In aqueous solution, a free volume constraint determines the amount of water molecules that transfer between a charging Fc-containing film and an aqua-solvated electrolyte. At low coverage, there is sufficient space for fully hydrated counteranions to associate with the Fc groups during charging because the Fc groups are separated sparsely.…”

Section: Introductionmentioning

confidence: 99%

On Electrogenerated Acid-Facilitated Electrografting of Aryltriazenes to Create Well-Defined Aryl-Tethered Films

et al. 2013

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The mechanism of electrogenerated acid-facilitated electrografting (EGAFE) of the aryltriazene, 4-(3,3-dimethyltriaz-1-enyl)benzyl-1-ferrocene carboxylate, was studied in detail using electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry. The measurements support the previously suggested mechanism that electrochemical oxidation of the EGA agent (i.e., N,N'-diphenylhydrazine) occurs on the forward oxidative sweep to generate protons, which in turn protonate the aryltriazene to form the corresponding aryldiazonium salt close to the electrode surface. On the reverse sweep, the electrochemical reduction of the aryldiazonium salt takes place, resulting in the electrografting of aryl groups. The EGAFE-generated film consists of a densely packed layer of ferrocenyl groups with nearly ideal electrochemical properties. The uncharged grafted film contains no solvent and electrolyte, but counterions and solvent can easily enter and be accommodated in the film upon charging. It is shown that all ferrocene moieties present in the multilayered film are electrochemically active, suggesting that the carbon skeleton possesses a sufficiently high flexibility to allow the occurrence of fast electron transfers between the randomly located redox stations. In comparison, EQCM measurements on aryldiazonium-grafted films reveal that they have a substantially smaller electrolyte uptake during charging and that they contain only 50% electroactive ferrocenyl groups relative to weight. Hence, half of these films consist of entrapped supporting electrolyte/solvent and/or simply electrochemically inactive material due to solvent inaccessibility.

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XPS Study of Counterion Incorporation into Poly(vinylferrocene)

Cited by 12 publications

References 38 publications

X-Ray Absorption Studies of Poly(vinylferrocene) Polymers for Anion Separation

X-Ray Absorption Studies of Poly(vinylferrocene) Polymers for Anion Separation

In Situ Preparation of Composite Redox-Active Micelles Bearing Pd Nanoparticles for the Reduction of 4-Nitrophenol

On Electrogenerated Acid-Facilitated Electrografting of Aryltriazenes to Create Well-Defined Aryl-Tethered Films

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