Organic layers at metal/electrolyte interfaces: molecular structure and reactivity of viologen monolayers

Breuer, S. W.; Pham, Duc Thanh; Huemann, Sascha; Gentz, Knud; Zoerlein, Caroline; Hunger, R.; Wandelt, K.; Broekmann, Peter

doi:10.1088/1367-2630/10/12/125033

Cited by 40 publications

(40 citation statements)

References 31 publications

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“…A new fitted peak at 400.3 eV could be attributed to the CN in neutral viologen. This result implies the formation of viologen by coupling two pyridinium salts . The C1s core level spectrum of IPP‐V (Figure e) could be fitted into five components located at 288.3, 287, 286.2, 285.3, and 284.6 eV, which could be ascribed to the carbon in residual CN, CN + in viologen, CN in the neutral viologen, alkyl units (CH 2 ), and aromatic unit (CC), respectively…”

Section: Resultsmentioning

confidence: 88%

Viologen‐Hypercrosslinked Ionic Porous Polymer Films as Active Layers for Electronic and Energy Storage Devices

Wang

Ding

Sun

et al. 2018

Adv Materials Inter

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compounds and inadequate quality of films for use as active materials. Therefore, many in situ film preparation approaches have been developed, such as polymer selfassembly [2] and in situ polymerization. [3] Of all approaches, electropolymerization has become increasingly popular because it enables fabricating uniform films rapidly. To date, many electroactive building blocks, such as carbazole, [4] aniline, [5] pyrrole, [6] thiophene, [7] and porphyrin, [8] have been reported. However, the preparation of porous polymer films through the electropolymerization method has been rarely reported.Memristor, which has wide applications in resistive access memory, [9] logic, [10] and neuro, [11] was originally envisioned in 1971 by Leon Chua and first realized with a 2-terminal device based on inorganic TiO 2 in 2008 by Williams and his coworkers. [12] Since then, memristors based on conductive/semiconductive polymers have been gradually developed due to the features of polymers, e.g., low cost, easy tunable optoelectronic properties, solvent processability, and flexibility. [9][10][11]13] With the miniaturization of electronic device, development and investigation of micropower -source which can be integrated with Si chips have been rising as the research focus. In-plane all-solid-state micro-supercapacitor (MSC) was one of the most popular candidates because of its high power density and ultrathin character. [14] In recent years, many electrode materials, especially carbon materials, have been developed in order to boost the performance. [15] However, carbon Over the past decades, numerous scientists have focused on designing complicated monomers, developing new synthesis protocols, and optimizing chemical structures for realizing high-performance organic or polymer electronics and energy storage devices. However, much less attention has been paid to ionic-and radical-rich porous organic films, which are essential components of aforementioned devices. In this study, an air-stable, large-area, freestanding, and viologen-linked ionic porous polymer (denoted as IPP-V) film is developed in situ through electrochemical polymerization. This film is applied to a device by sandwiching it between indium tin oxide (ITO) and Au (i.e., ITO/ IPP-V/Au); the device exhibits a memristive behavior with an ON-OFF current ratio of ≈2. After the IPP-V film is subjected to thermal pyrolysis at 500 °C, the as-produced film (denoted as IPP-V-500) acts as an active material for an in-plane micro-supercapacitor and exhibits a high volumetric capacitance level of up to 4.44 F cm −3 . This work not only offers a new and convenient strategy toward large-area ionic porous polymer films for memristor, but also provides a new porous polymer derived carbon film for energy storage.

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Section: Resultsmentioning

confidence: 88%

Viologen‐Hypercrosslinked Ionic Porous Polymer Films as Active Layers for Electronic and Energy Storage Devices

Wang

Ding

Sun

et al. 2018

Adv Materials Inter

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“…9 . The dicationic character of the DBV 2+ building blocks of this cavitand structure was verified by ex situ XPS measurements using synchrotron radiation, namely by a dominant N(1s) signal at 402.1 eV [ 27 ]. Sweeping the electrode potential to a value below −200 mV vs RHE causes the disintegration of the cavitand structure and the formation of a stripe pattern ( Fig.…”

Section: Discussionmentioning

confidence: 99%

“…First of all in both the DBV 2+ dication and the DBV +• monocation radical species the positive charge resides on the N-containing bipyridinium core as revealed by the N(1s) photoemission spectra [ 27 ], while the two benzyl groups, decoupled from the delocalized π-system of the bipyridinium core by the two CH 2 groups, are relatively more negatively charged. As a consequence the preferred adsorbate–adsorbate interactions are electrostatic attractions between the positive bipyridinium cores and the benzyl groups.…”

Section: Discussionmentioning

confidence: 99%

Molecular ordering at electrified interfaces: Template and potential effects

Phan¹,

Wandelt²

2014

Beilstein J. Org. Chem.

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SummaryA combination of cyclic voltammetry and in situ scanning tunneling microscopy was employed to examine the adsorption and phase transition of 1,1’-dibenzyl-4,4’-bipyridinium molecules (abbreviated as DBV2+) on a chloride-modified Cu(111) electrode surface. The cyclic voltammogram (CV) of the Cu(111) electrode exposed to a mixture of 10 mM HCl and 0.1 mM DBVCl2 shows three distinguishable pairs of current waves P1/P’1, P2/P’2, and P3/P’3 which are assigned to two reversible electron transfer steps, representing the reduction of the dicationic DBV2+ to the corresponding radical monocationic DBV+• (P1/P’1) and then to the uncharged DBV0 (P3/P’3) species, respectively, as well as the chloride desorption/readsorption processes (P2/P’2). At positive potentials (i.e., above P1) the DBV2+ molecules spontaneously adsorb and form a highly ordered phase on the c(p × √3)-precovered Cl/Cu(111) electrode surface. A key element of this DBV2+ adlayer is an assembly of two individual DBV2+ species which, lined up, forms a so-called “herring-bone” structure. Upon lowering the electrode potential the first electron transfer step (at P1) causes a phase transition from the DBV2+-related herring-bone phase to the so-called "alternating stripe" pattern built up by the DBV+• species following a nucleation and growth mechanism. Comparison of both observed structures with those found earlier at different electrode potentials on a c(2 × 2)Cl-precovered Cu(100) electrode surface enables a clear assessment of the relative importance of adsorbate–substrate and adsorbate–adsorbate interactions, i.e., template vs self-assembly effects, in the structure formation process of DBV cations on these modified Cu electrode surfaces.

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“…[17][18][19][20] Combining the CV features of other viologen species on a Cu(100) electrode with those of heptyl viologen on an HOPG and Au electrode, it is possible to propose an assignment for all current waves of heptyl viologen present in the CVs on the Cu(100) electrode. There is no doubt that the peak pairs P 1 /P 1 ' should correspond to the first one-electron transfer step (DHV 2 + /DHVC + ) of surface species in the presence of the chloride adlayers, while P 2 /P 2 ' might be assigned to a further reorientation of the radical cationic DHVC + phase on the chloride adlayers.…”

Section: Electrochemical Behaviour Of Heptyl Viologen On a Cu(100) Elmentioning

confidence: 99%

“…[9,10,[12][13][14][15] Such a model has been applied in the adsorption of viologen species on metal electrodes. [16][17][18][19][20] Viologens (N,N'-disubstituted-4,4'-bipyridinium molecules) are one important class of redox-active compounds which have attracted much attention as electron-transfer mediators in photochemical devices for solar energy conversion and as materials for electrochromic displays. [21][22][23] The heptyl viologen (1,1'-diheptyl-4,4'-bipyridinium, DHV) bromide salt was first studied for electrochromic devices in the 1970s, as their oneelectron reduction of the dicationic DHV 2 + to the mono-cationic radical salt DHVC + Br À in aqueous solutions formed a violet precipitate on electrode surfaces.…”

Section: Introductionmentioning

confidence: 99%

Redox Activity and Structural Transition of Heptyl Viologen Adlayers on Cu(100)

Jiang¹,

Sak²,

Gentz³

et al. 2010

ChemPhysChem

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The redox behaviour and potential-dependent adsorption structure of heptyl viologen (1,1'-diheptyl-4,4'-bipyridinium dichloride, DHV(2+)) on a Cu(100) electrode was investigated in a chloride-containing electrolyte solution by cyclic voltammetry (CV) and in situ electrochemical scanning tunneling microscopy (EC-STM). The dicationic DHV molecules generate a few pairs of current waves in CV measurements which are ascribed to two typical one-electron transfer steps. STM images obtained in a KCl-containing electrolyte solution disclose a well-ordered c(2x2) chloride adlayer on a Cu(100) electrode surface. After injecting DHV(2+) molecules into the KCl electrolyte solution, a highly ordered 2D "dot-array" structure in STM images emerges on the c(2x2)-Cl modified Cu(100) electrode surface. DHV(2+) molecules spontaneously arrange themselves with their molecular planes facing the electrode surface and their long molecular axis parallel to the step edge. Such adsorption structure can be described by mirror domains and rotational domains which stably exist between 200 mV and -100 mV. One-electron reduction of the dications DHV(2+) around -150 mV causes a phase transition from a 'dot-array' assembly to a stripe pattern formed by DHV(*+) radical monocations in STM images which has a bilayer structure. With a further decrease of the applied electrode potential, the structure of the DHV(*+) adlayer undergoes a change from a loose stripe phase to a more compact stripe phase, a subsequent decay of the compact structure, and finally the formation of a new dimer phase. A further electron transfer reaction at -400 mV causes the formation of an amorphous phase on the chloride free electrode surface. In a reverse anodic sweep, the reproduction of the ordered DHV(*+) stacking phase occurs again on top of the chloride lattice.

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Organic layers at metal/electrolyte interfaces: molecular structure and reactivity of viologen monolayers

Cited by 40 publications

References 31 publications

Viologen‐Hypercrosslinked Ionic Porous Polymer Films as Active Layers for Electronic and Energy Storage Devices

Viologen‐Hypercrosslinked Ionic Porous Polymer Films as Active Layers for Electronic and Energy Storage Devices

Molecular ordering at electrified interfaces: Template and potential effects

Redox Activity and Structural Transition of Heptyl Viologen Adlayers on Cu(100)

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