Anna Prokhorova, Katrin Sturm-Richter, Andreas Doetsch et al.

Applied and Environmental Microbiology • 2017

ABSTRACT Anode-associated multispecies exoelectrogenic biofilms are essential for the function of bioelectrochemical systems (BESs). The individual activities of anode-associated organisms and physiological responses resulting from coculturing are often hard to assess due to the high microbial diversity in these systems. Therefore, we developed a model multispecies biofilm comprising three exoelectrogenic proteobacteria, Shewanella oneidensis , Geobacter sulfurreducens , and Geobacter metallireducens , with the aim to study in detail the biofilm formation dynamics, the interactions between the organisms, and the overall activity of an exoelectrogenic biofilm as a consequence of the applied anode potential. The experiments revealed that the organisms build a stable biofilm on an electrode surface that is rather resilient to changes in the redox potential of the anode. The community operated at maximum electron transfer rates at electrode potentials that were higher than 0.04 V versus a normal hydrogen electrode. Current densities decreased gradually with lower potentials and reached half-maximal values at −0.08 V. Transcriptomic results point toward a positive interaction among the individual strains. S. oneidensis and G. sulfurreducens upregulated their central metabolisms as a response to cultivation under mixed-species conditions. G. sulfurreducens was detected in the planktonic phase of the bioelectrochemical reactors in mixed-culture experiments but not when it was grown in the absence of the other two organisms. IMPORTANCE In many cases, multispecies communities can convert organic substrates into electric power more efficiently than axenic cultures, a phenomenon that remains unresolved. In this study, we aimed to elucidate the potential mutual effects of multispecies communities in bioelectrochemical systems to understand how microbes interact in the coculture anodic network and to improve the community's conversion efficiency for organic substrates into electrical energy. The results reveal positive interactions that might lead to accelerated electron transfer in mixed-species anode communities. The observations made within this model biofilm might be applicable to a variety of nonaxenic systems in the field.

K. W. Willman, R. Rocklin, R. Nowak et al.

Journal of the American Chemical Society • 1980

Abstract : Depending on silanization reaction conditions, aminophenylferrocene and tetrakis (p-aminophenyl) porphyrin can be covalently attached in monolayer or multi-molecular layer quantities to glassy carbon and superficially oxidized Pt electrodes using 4-(methyldichlorosily)butyryl chloride. This study applies various spectroscopies to surface structure of the attached porphyrin: XPS (number of surface amide bonds), fluorescence (quantity of porphyrin attached to a siloxane polymer film compared to quantity of electroactive porphyrin), and reflectance spectroscopies (spectroelectrochemical observation of oxidation state changes with electrode under potential control, including an electrochemically silent Co(III/II) porphyrin reaction). Electroactive films 500 monolayers thick can be prepared from the ferrocene by spin coating reactive silane; in aqueous sulfuric acid voltammetry of these films indicates a phase-like property. (Author)

Laura E. Barrosse-Antle, C. Hardacre, R. Compton

The Journal of Physical Chemistry B • 2009

The effects of such solutes such as halides and water on the physical properties of room temperature ionic liquids (RTILs) have been extensively studied. This work examines the effect of the solute carbon dioxide on the RTIL 1-ethyl-3-methylimidazolium bis(trifluoromethane-sulfonyl)imide ([C2mim][NTf2]) and its influence on the electrochemical characterization of the important redox couple ferrocene/ferrocenium (Fc/Fc+). The system was studied using cyclic voltammetry, chronoamperometry, and electron spin resonance (ESR) spectroscopy. Addition of 100% CO2 to a solution of Fc in [C2mim][NTf2] resulted in a substantial increase in both the limiting oxidative current and diffusion coefficient of Fc. Arrhenius plots of Fc diffusion coefficients in the pure and CO2-saturated ionic liquid revealed a decrease in activation energy of translational diffusion from 29.0 (+/- 0.5) kJ mol(-1) to 14.7 (+/- 1.6) kJ mol(-1), suggesting a reduction in the viscosity of the ionic liquid with addition of CO2. ESR spectroscopy was then used to calculate the rotational correlation coefficients of a probe molecule, 2,2,6,6-tetramethyl-1-piperinyloxyl (TEMPO), to add supporting evidence to this hypothesis. Arrhenius plots of rotational correlation coefficients in the pure and CO2-saturated ionic liquid resulted in a similar drop in activation energy from 28.7 (+/- 2.1) kJ mol(-1) to 18.2 (+/- 5.6) kJ mol(-1). The effect of this solute on the ionic liquid [C2mim][NTf2] and on the electrochemical measurements of the Fc/Fc+ couple emphasizes the necessity of fastidious sample preparation, as it is clear that the voltammetric currents of the electroactive species under study are influenced by the presence of CO2 in solution. The voltammetric response of the electroactive species in RTILs cannot be assumed to be independent of other solutes.

S. Daniele, M. Baldo, C. Bragato

Journal of the Brazilian Chemical Society • 2002

Mercury coated platinum microelectrodes were employed for the in situ determination, in soils and porewater of sediments, of redox key species of environmental interest. Sand samples were considered as soil model for the in situ detection of oxygen. Direct measurements of sulphide were performed in anoxic sediments collected in the Lagoon of Venice. An investigation on the interaction among heavy metals, sulphide and solid particles in pore-water extracted from the sediments was also performed. For the quantification of the various electroactive species examined, calibrantioless procedures were employed.

R. Martínez, M. Ramírez, I. González

Electroanalysis • 1998

The voltammetric characterization of ferrocene confined within a carbon paste electrode (CPE) with nonconducting binder (Nujol or silicon oil) was performed. The voltammetric behavior depends directly on the way in which the electroactive species were introduced into the paste: as a solid or previously dissolved into the binder. These two forms were found to contribute in the electrochemical process in a single voltammetric peak. Variations in the potential sweep rate, type of binder (meaning changes in ferrocene solubility), the amount of binder in the paste, and also the amount of the electroactive species affect the shape of the voltammetric curves obtained. This enables us to distinguish between the contributions of the solid and dissolved forms of ferrocene in the voltammetric response. From this study, it is established that the ferrocene oxidation in CPE was limited by diffusion, taking place in a layer beyond the electrode–electrolyte interface, resulting from the dissolution of ferrocene within the binder. The existing controversy reported for voltammetric studies of ferrocene in CPE could be explained by the presence of two different ferrocene species involved in the oxidation process.

Yu Ding, Changkun Zhang, Leyuan Zhang et al.

Chemical Society Reviews • 2018

With high scalability and independent control over energy and power, redox flow batteries (RFBs) stand out as an important large-scale energy storage system. However, the widespread application of conventional RFBs is limited by the uncompetitive performance, as well as the high cost and environmental concerns associated with the use of metal-based redox species. In consideration of advantageous features such as potentially low cost, vast molecular diversity, and highly tailorable properties, organic and organometallic molecules emerge as promising alternative electroactive species for building sustainable RFBs. This review presents a systematic molecular engineering scheme for designing these novel redox species. We provide detailed synthetic strategies for modifying the organic and organometallic redox species in terms of solubility, redox potential, and molecular size. Recent advances are then introduced covering the reaction mechanisms, specific functionalization methods, and electrochemical performances of redox species classified by their molecular structures. Finally, we conclude with an analysis of the current challenges and perspectives on future directions in this emerging research field.

Huaifang Zhang, Pei-luo Shi, Xiao Ma et al.

Advanced Energy Materials • 2022

Benefiting from ordered atomic structures and strong d‐orbital interactions, intermetallic compounds (IMCs) are promising electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, the body‐centered cubic IrGa IMCs with atomic donor–acceptor architectures are synthesized and anchored on the nitrogen‐doped reduced graphene oxide (i.e., IrGa/N‐rGO). Structural characterizations and theoretical calculations reveal that the electron‐rich Ir sites are atomically dispersed in IrGa/N‐rGO, facilitating the electron transfer between Ir atoms and adsorbed species, which can efficiently decrease the energy barriers of the potential determining step for both HER and OER. Impressively, the IrGa/N‐rGO||IrGa/N‐rGO exhibits excellent performance for overall water splitting in alkaline medium, requiring a low cell voltage of 1.51 V to achieve 10 mA cm−2, meanwhile, exhibiting no significant degradation for 100 h. This work demonstrates that the rational design of noble metal electrocatalysts with donor–acceptor architectures is beneficial for catalytic reactions in energy conversion applications.

D. Zigah, Jean‐Marc Noël, C. Lagrost et al.

The Journal of Physical Chemistry C • 2010

Electron transfers in modified polyaryl multilayers containing redox active molecules (ferrocenyl moieties) have been investigated by scanning electrochemical microscopy (SECM) in feedback mode. The modified surfaces were prepared by the electro-reduction of aryl diazonium salts that provides anchoring layers for the immobilization of the electroactive groups. Two types of anchoring films were prepared, the first with aminophenyl and the second with phenylcarboxylic acid groups, allowing us to vary the oxidation level of the electroactive film. Determination of the apparent electron transfer rates between the modified surface and a series of redox mediators displaying increasing standard potentials permits the analysis of different processes involved in the charge transfer, namely, the permeation of the organic molecules (the mediator) and the conduction mechanism. In addition to the first oxidation of the immobilized molecules by the mediator at the solution−film interface, the global oxidation kinetics ...

Julien Sarmet, F. Leroux, C. Taviot‐Gueho et al.

Molecules • 2023

By selecting two electroactive species immobilized in a layered double hydroxide backbone (LDH) host, one able to act as a positive electrode material and the other as a negative one, it was possible to match their capacity to design an innovative energy storage device. Each electrode material is based on electroactive species, riboflavin phosphate (RF) on one side and ferrocene carboxylate (FCm) on the other, both interleaved into a layered double hydroxide (LDH) host structure to avoid any possible molecule migration and instability. The intercalation of the electroactive guest molecules is demonstrated by X-ray diffraction with the observation of an interlayer LDH spacing of about 2 nm in each case. When successfully hosted into LDH interlayer space, the electrochemical behavior of each hybrid assembly was scrutinized separately in aqueous electrolyte to characterize the redox reaction occurring upon cycling and found to be a rapid faradic type. Both electrode materials were placed face to face to achieve a new aqueous battery (16C rate) that provides a first cycle-capacity of about 7 mAh per gram of working electrode material LDH/FCm at 10 mV/s over a voltage window of 2.2 V in 1M sodium acetate, thus validating the hybrid LDH host approach on both electrode materials even if the cyclability of the assembly has not yet been met.

S. Branagan, N. M. Contento, P. Bohn

Journal of the American Chemical Society • 2012

Electroosmotic flow (EOF) is used to enhance the delivery of Fe(CN)(6)(4-)/Fe(CN)(6)(3-) to an annular nanoband electrode embedded in a nanocapillary array membrane, as a route to high efficiency electrochemical conversions. Multilayer Au/polymer/Au/polymer membranes are perforated with 10(2)-10(3) cylindrical nanochannels by focused ion beam (FIB) milling and subsequently sandwiched between two axially separated microchannels, producing a structure in which transport and electron transfer reactions are tightly coupled. The middle Au layer, which contacts the fluid only at the center of each nanochannel, serves as a working electrode to form an array of embedded annular nanoband electrodes (EANEs), at which sufficient overpotential drives highly efficient electrochemical processes. Simultaneously, the electric field established between the EANE and the QRE (>10(3) V cm(-1)) drives electro-osmotic flow (EOF) in the nanochannels, improving reagent delivery rate. EOF is found to enhance the steady-state current by >10× over a comparable structure without convective transport. Similarly, the conversion efficiency is improved by approximately 10-fold compared to a comparable microfluidic structure. Experimental data agree with finite element simulations, further illustrating the unique electrochemical and transport behavior of these nanoscale embedded electrode arrays. Optimizing the present structure may be useful for combinatorial processing of on-chip sample delivery with electrochemical conversion; a proof of concept experiment, involving the generation of dissolved hydrogen in situ via electrolysis, is described.

E. Fell, Diana De Porcellinis, Yan Jing et al.

Journal of The Electrochemical Society • 2023

We assess the suitability of potassium ferri-/ferrocyanide as an electroactive species for long-term utilization in aqueous organic redox flow batteries. A series of electrochemical and chemical characterization experiments was performed to distinguish between structural decomposition and apparent capacity fade of ferri-/ferrocyanide solutions used in the capacity-limiting side of a flow battery. Our results indicate that, in contrast with previous reports, no structural decomposition of ferri-/ferrocyanide occurs at tested pH values as high as 14 in the dark or in diffuse indoor light. Instead, an apparent capacity fade takes place due to a chemical reduction of ferricyanide to ferrocyanide, via chemical oxygen evolution reaction. We find that this parasitic process can be further exacerbated by carbon electrodes, with apparent capacity fade rates at pH 14 increasing with an increased ratio of carbon electrode surface area to ferricyanide in solution. Based on these results, we report a set of operating conditions that enables the long-duration cycling of alkaline ferri-/ferrocyanide electrolytes and demonstrate how apparent capacity fade rates can be engineered by the initial system setup. If protected from direct exposure to light, the structural stability of ferri-/ferrocyanide anions allows for their practical deployment as electroactive species in long duration energy storage applications.

Ai Sugitani, Takeshi Watanabe, T. Ivandini et al.

Phys. Chem. Chem. Phys. • 2013

Selective anodic stripping voltammetry of trace metal ions in a mixture solution with another interfering metal was developed based on Fick's law concerning the diffusion profile of interfering metals at the electrode surface after electrolysis treatment. A boron-doped diamond film was used as the sensing electrode, while a perforated carbon sheet was used for the interference-depleting electrode. The influence of the electrode distance and the time of electrolysis on the formation of the diffusion profile was studied. As a working model, the detection of cadmium with copper interference was investigated. The advantage of the method in comparison to general electrolysis was also discussed. The method offers a new perspective for improving the selective detection of metal ions by analyzing the diffusion profiles of the interfering species at the surface of electrodes.

S. H. Oh, C.-W. Lee, D. Chun et al.

J. Mater. Chem. A • 2014

A metal-free and all-organic redox flow battery is proposed and investigated. It employs polythiophene microparticles dispersed in electrolyte solutions as the redox couple and does not depend on limited metal resources. It shows a high cell potential and stable charge/discharge performance with a high energy efficiency of 60.9%.

Estefanía Baigorria, J. Durantini, S. R. Martínez et al.

ACS Applied Bio Materials • 2021

The spreading of different infections can occur through direct contact with glass surfaces in commonly used areas. Incorporating the use of alternative therapies in these materials seems essential to reduce and also avoid bacterial resistance. In this work, the capability to kill microbes of glass surfaces coated with two electroactive metalated phthalocyanines (ZnPc-EDOT and CuPc-EDOT) is assessed. The results show that both of these materials are capable of producing reactive oxygen species; however, the polymer with Zn(II) (ZnPc-PEDOT) has a singlet oxygen quantum yield 8-fold higher than that of the Cu(II) containing analogue. This was reflected in the in vitro experiments where the effectiveness of the surfaces was tested in bacterial suspensions, monitoring single microbe inactivation upon attachment to the polymers, and eliminating mature biofilms. Furthermore, we evaluated the use of an inorganic salt (KI) to potentiate the photodynamic inactivation mediated by an electropolymerized surface. The addition of the salt improved the efficiency of phototherapy at least two times for both polymers; nevertheless, the material coated with ZnPc-PEDOT was the only one capable of eliminating >99.98% of the initial microbes loading under different circumstances.

Daniel Martín‐Yerga, E. C. Rama, A. C. Garcia

Journal of Chemical Education • 2016

A lab appropriate to introduce voltammetric techniques and basic electrochemical parameters is described in this work. It is suitable to study theoretical concepts of electrochemistry in an applied way for analytical undergraduate courses. Two electroactive species, hexaammineruthenium and dopamine, are used as simple redox systems. Screen-printed electrodes are used in order to allow the students to focus on the electrochemistry and avoid tedious instrumentation preparation. The analytical determination of the species studied with sensitive techniques such as differential-pulse or square-wave voltammetry is also performed.

Takuya Okazaki, Tatsuya Orii, Shin-Yinn Tan et al.

Analytical Chemistry • 2020

We present an electrochemical long period fiber grating (LPFG) sensor for electroactive species with an optically transparent electrode. The sensor was fabricated by coating indium tin oxide onto the surface of LPFG using a polygonal barrel-sputtering method. LPFG was produced by an electric arc-induced technique. The sensing is based on change in the detec-tion of electron density on the electrode surface during potential application and its reduction by electrochemical redox of analytes. Four typical electroactive species of methylene blue, hexaammineruthenium(III), ferrocyanide and ferrocenedi-methanol were used to investigate the sensor performance. The concentrations of analytes were determined by the modula-tion of the potential as the change in transmittance around the resonance band of LPFG. The sensitivity of the sensor, par-ticularly to methylene blue, was high, and the sensor responded to a wide concentration range of 0.001 mM to 1 mM.

Lucila Martinez Ostormujof, Sébastien Teychené, Wafa Achouak et al.

ChemElectroChem • 2023

Abstract The decrease in the electrochemical activity of multi‐species microbial anodes in bioelectrochemical systems is the main bottleneck to overcome for bringing these technologies one‐step closer to the industrialization stage. In this study, microsized stainless steel electrodes were implemented to investigate the distinctive electrochemical behavior of salt marsh electroactive biofilms (EABs). Four main temporal stages of biocolonization and electrochemical activity were thoroughly described. Maximum biofilm growth rate, high viability and high extracellular protein matrix content favored the increasing electrochemical activity of the EAB up to its maximum current peak. Then, when gradual fall in current became irreversible, biofilm growth rate decreased together with dead cells accumulation and an increase for extracellular polysaccharides. In addition, analyses of microbial populations showed a shift from Marinobacterium spp. to Desulfuromonas spp. These findings suggest a chemical and microbial temporal evolution of the EAB, which can be directly correlated to the electrochemical performance of the bioanode.

Nicolò Dossi, Rosanna Toniolo, Fabio Terzi et al.

ELECTROPHORESIS • 2015

We propose here simple electrochemical cells assembled with electrodes pencil drawn on paper for conducting one‐spot tests enabling olive oil to be easily distinguished from other vegetable oils. They consist of small circular pads of hydrophilic paper defined by hydrophobic barriers, these last printed by using custom‐designed rubber stamps, where working, reference, and counterelectrodes are drawn by pencil leads. These cells were first wetted with a small volume of aqueous electrolyte, avoiding coating of the upper surface of electrodes. A controlled volume of edible oil samples was then applied on top of the moist cell. The results found proved that these devices can be adopted as effective platforms suitable for the detection of electroactive compounds present in edible oils. In fact, they allow voltammetric profiles to be recorded not only for the oxidation of water soluble species (ortho‐diphenols, as well as some monophenols and polyphenols) present in olive oils, but also for electroactive hydrophobic components (e.g., α‐tocopherol) present in sunflower oils, which were chosen as model of seed oils. The whole of collected findings pointed out that simple one‐spot tests performed by these devices enable olive oils to be easily distinguished from other edible oils on the basis of their clearly different voltammetric profiles. A satisfactory interdevice reproducibility (±13%) was estimated by applying strictly similar extra virgin olive oil samples onto seven different cells carefully prepared by the same procedure. An operating mechanism able to account for the detection of also electroactive hydrophobic compounds present in oils is proposed.

Dulan B. Gunasekara, Manjula B. Wijesinghe, Pann Pichetsurnthorn et al.

The Analyst • 2020

Dual-channel/dual-parallel electrode configuration for microchip electrophoresis with electrochemical detection for voltammetric characterization of electrochemically active analytes in biological samples.

Alexander Oleinick, Yun Yu, Michael V. Mirkin et al.

ChemElectroChem • 2019

Abstract The electron transfer/ion transfer mode of scanning electrochemical microscopy (SECM), in which a nanopipette containing a solvent immiscible with the outer solution is used as a tip to approach a microelectrode substrate, is investigated by simulations in order to analyze the effect of the electroactive species being simultaneously present inside the nanopipette and in the external liquid phase. The simulations consider conventional transport modes of the species inside the nanopipette as well as in the bulk solution coupled with their transfer across the liquid‐liquid nanointerface supported at the nanopipette tip. The shapes of the simulated approach curves (tip current vs. tip‐substrate distance) are highly sensitive to the ratio of initial concentrations in the nanopipette and in the outer solution for a given partition coefficient value providing a direct method to determine its value. The effect of the 1 st and 2 nd order homogeneous reaction consuming the product electrogenerated at the microelectrode surface onto its collection by the nanopipette is also presented.

Sabine Szunerits, Patrick Garrigue, Jean‐Luc Bruneel et al.

Electroanalysis • 2003

Abstract The fabrication of an ordered electrode array based on an etched optical fiber bundle is described. The high density sub‐micrometer electrode array is characterized electrochemically using cyclic voltammetry and geometrically via scanning electron microscopy. The observed steady‐state current indicates that individual diffusion layers do not overlap and that the electrodes are diffusively independent. Spatially resolved chemical information of the etched and insulating paint‐covered surface of the electrode array is obtained from confocal Raman microspectroscopy (CRM) experiments. Finally electroactive spots are probed using CRM through the different Raman spectra of the electroactive species of the redox couple Fe(CN) 6 3− /Fe(CN) 6 4− .

Parbury P. Schmidt, Harry B. Mark

The Journal of Chemical Physics • 1965

It is assumed in this paper that at the electrode—solution interface there is molecular order of the electroactive species resembling solid-state order. Specifically, it is assumed that next to the electrode is a layer of adsorbed neutral solvent molecules which are also ligands coordinated to the ions found in the interface. The mechanism of electron transfer from the electrode to the ion or the reverse from the ion to the electrode is assumed initially to involve a transition from either the electrode or the ion to the solvent molecule. This is followed by a transition of the electron from the solvent molecule to either the ion or the electrode. The two transitions involved in the net transfer of an electron across the interface are considered analogous to the charge-transfer mechanism of spectroscopy. The wavefunctions representing the system at the interface are then of the same form as the charge-transfer wavefunctions given by Mulliken. By considering the radiationless transition probabilities for the electron transitions in the interface system at the electrode, it is found that the usual current expressions result. By imposing the condition of zero net current at equilibrium the Nernst equation results. By further considering the polarization of the electrode under nonequilibrium conditions as a perturbation of the energy levels of the system, it is found that with the proper identification of terms the current expression for the polarized electrode results.

Paniz Izadi, Uwe Schröder

ChemElectroChem • 2022

Abstract Desulfarculus baarsii and Desulfurivibrio alkaliphilus are strictly anaerobic bacteria existing in marine sediments. D. baarsii gains energy through reducing sulphate and D. alkaliphilus is able to reduce elemental sulphur, thiosulphate and polysulphide in seawater. Both organisms were previously identified as key organisms in sediment derived, bidirectional electroactive biofilms. Here, we investigated the electrochemical performance of these two bacteria in bio‐electrochemical systems and their possible involvement in anodic and cathodic reactions. The results show that D. baarsii was unable to donate or accept electrons to/from an electrode, while D. alkaliphilus was able to catalyse both anodic and cathodic reactions and interact with the electrode through direct or potentially indirect electron transfer. Raman spectra of D. alkaliphilus electrode biofilms showed a high similarity to Geobacter sulfurreducens biofilms, including the specific bands of cytochromes b and c, explaining the electroactivity of D. alkaliphilus in bioelectrochemical reactions.

Dmitry Konev, Olga Istakova, Mikhail Vorotyntsev

Membranes • 2022

A novel method has been proposed for rapid determination of principal transmembrane transport parameters for solute electroactive co-ions/molecules, in relation to the crossover problem in power sources. It is based on direct measurements of current for the electrode, separated from solution by an ion-exchange membrane, under voltammetric and chronoamperometric regimes. An electroactive reagent is initially distributed within the membrane/solution space under equilibrium. Then, potential change induces its transformation into the product at the electrode under the diffusion-limited regime. For the chronoamperometric experiment, the electrode potential steps backward after the current stabilization, thus inducing an opposite redox transformation. Novel analytical solutions for nonstationary concentrations and current have been derived for such two-stage regime. The comparison of theoretical predictions with experimental data for the Br2/Br− redox couple (where only Br− is initially present) has provided the diffusion coefficients of the Br− and Br2 species inside the membrane, D(Br−) = (2.98 ± 0.27) 10−6 cm2/s and D(Br2) = (1.10 ± 0.07) 10−6 cm2/s, and the distribution coefficient of the Br− species at the membrane/solution boundary, K(Br−) = 0.190 ± 0.005, for various HBr additions (0.125–0.75 M) to aqueous 2 M H2SO4 solution. This possibility to determine transport characteristics of two electroactive species, the initial solute component and its redox product, within a single experiment, represents a unique feature of this study.

Serge Cosnier, Rodica E. Ionescu, Michel Keddam et al.

Electroanalysis • 2008

Abstract The carbon cavity microelectrode (CME), exhibiting a volume of 4×10 −6 cm 3 , offers a genuine alternative for immobilizing and connecting enzymes in aqueous electrolytes by powder of insoluble redox materials. In the present work, the electrochemical behavior of two redox species such as ferrocene (Fc) and tetrathiafulvalene (TTF) was investigated with CME to evaluate their potentialities in the electrical wiring of enzymes. For this purpose, powder of two enzymes, glucose oxidase (GOx) and horseradish peroxidase (HRP), was independently mixed with an insoluble redox material and forced to fill the single micro cavity of a carbon electrode covered by an inert insulator. The presence of the electroactive species, as well as the enzyme wiring was investigated by cyclic voltammetry. The amperometric detection of glucose was carried out by potentiostating the TTF/GOx and the Fc/GOx microelectrodes at 0.25 and 0.35 V respectively. The amperometric detection of H 2 O 2 by the TTF/HRP microelectrode was performed at −0.1 V vs. SCE.

Larry R. Gibson, Sean P. Branagan, Paul W. Bohn

Small • 2013

Abstract Significant technological drivers motivate interest in the use of reaction sites embedded within nanometer‐scale channels, and an important class of these structures is realized by an embedded annular nanoband electrode (EANE) in a cylindrical nanochannel. In this structure, the convective delivery of electroactive species to the nanoelectrode is tightly coupled to the electrochemical overpotential via electroosmotic flow. Simulation results indicate that EANE arrays significantly outperform comparable microband electrode/microchannel structures, producing higher conversion efficiencies at low Peclet number. The results of this in‐depth analysis are useful in assessing possible implementation of the EANE geometry for a wide range of electrochemical targets within microscale total analysis systems.

Huafang Zhou, Guangli Che, Shaojun Dong

Electroanalysis • 1997

Abstract The mass transport dynamics of ferrocene in polyelectrolyte polyethylene glycol lithium perchlorate (PEG · LiClO 4 ) was studied by using chronoamperometry at a microdisk electrode. Chronoamperometry is a powerful method for the study of mass transport in polyelectrolyte, it has many advantages over the conventional methods at a microelectrode and the steady‐state method at an ultramicroelectrode. By using this method the apparent diffusion coefficient D app and concentration C a of the electroactive species, can be estimated from a single experiment without previous knowledge of either one. We have estimated D app and C a of ferrocene in PEG · LiClO 4 polyelectrolyte from 25°C to 75°C. The dependence on the concentration of electroactive species was observed. The diffusion coefficients decrease with increasing ferrocene concentration and decreasing temperature. The mass transport mechanism is explained by using a free volume model.

Christoph J. Bondue, Marius Spallek, Lennart Sobota et al.

ChemSusChem • 2023

Abstract To date the electroactive species of selective aldehyde oxidation to carboxylates at gold electrodes is usually assumed to be the diolate. It forms with high concentration only in very alkaline electrolytes, when OH − binds to the carbonyl carbon atom. Accordingly, the electrochemical upgrading of biomass‐derived aldehydes to carboxylates is believed to be limited to very alkaline electrolytes at many electrode materials. However, OH − ‐induced aldehyde decomposition in these electrolytes prevents application of electrochemical aldehyde oxidation for the sustainable upgrading of biomass to value‐added chemicals at industrial scale. Here, we demonstrate the successful oxidation of aliphatic aldehydes at a rotating gold electrode at pH 12, where only 1 % of the aldehyde resides as the diolate species. This concentration is too small to account for the observed current, which shows that also other aldehyde species (i. e., the geminal diol and the non‐hydrated aldehyde) are electroactive. This insight allows developing strategies to omit aldehyde decomposition while achieving high current densities for the selective aldehyde oxidation, making its future industrial application viable.

Ilana Fried

Israel Journal of Chemistry • 1969

Abstract Rigorous mathematical treatment of the classical theory of diffusion of an electroactive species to an electrode exposes an error in the theory. According to the corrected theory, the initial concentration (at t = 0) of the electroactive species is uniform throughout the solution except at the electrode surface. Fortunately, diffusion theory results remain unaltered. Two important conclusions result from the corrected theory: a. the plane of the “electrode surface” is inside the diffuse double layer, and b. the exact function of the concentration of the electroactive species in the double layer has no effect on the solution of the diffusion equation. These results, although intuitively accepted, are rigorously proved.

P. Jenčušová, P. Tomčík, D. Bustin et al.

Chemical Papers • 2006

Abstract The possibility of calibrationless chronoamperometric determination is described using a pair of individually addressable and diffusion layers interacting segments of interdigitated microelectrode array (IDA). It utilizes dual voltammetric mode where the first segment is polarized with potential corresponding to the limiting current of determined species electrode reaction and the second segment is polarized with potential corresponding to the opposite electrode reaction limiting current. Time at which the current of the collector segment reaches one half of the steady state is hyperbolically dependent on the diffusion coefficient of analyte. The determination of diffusion coefficient allows direct calculation of bulk concentration avoiding calibration with a standard solution. The equipment for measuring of fast response of IDA arrays in dual mode has been developed using a bipotentiostat connected with A/D transducer. It allows less than 1 ms sampling period for ultrafast registration of chronoamperogram. The method was tested and validated with [Fe(CN)6]4−, [Ru(NH3)6]Cl3, and ferrocene model samples using various types of IDA arrays.

Nazario Martin

ECS Meeting Abstracts • 2015

The readily available and highly versatile electron donor exTTF molecule has proved its efficiency for the design of unprecedented receptors for fullerenes and other carbon nanoforms. In this regard, custom-made tweezers and macrocyclic receptors are proving a valuable alternative to achieve the affinity and selectivity required to meet goals such as the selective extraction of higher fullerenes, their chiral resolution or the self-assembly of functional molecular materials. [1] In this presentation some important breakthroughs based on electroactive systems derived from exTTF as molecular and macrocyclic receptors for single wall carbon nanotubes will be highlighted. Bowl and belt-shaped CNTs receptors based on this concave-convex complementarity principle will also be presented. [2] The recognition motives have been applied with the aim of modifying their electronic properties, [3] as well as for the hierarchical organization of mesoscopic 3D helical fibers. [4] References: [1] a) E. M. Pérez, L. Sánchez, G. Fernández, N. Martín, J. Am. Chem. Soc ., 2006 , 128 , 7172-7173; b) E. M. Pérez, N. Martín, Chem. Soc. Rev ., 2008 , 37 , 1512-1519; c) D. Canevet, E. M. Pérez, N. Martín, Angew. Chem. Int. Ed . 2011 , 50 , 9248 – 9259. [2] a) M. Gallego, J. Calbo, J. Aragó, R. M. Krick Calderon, F. H. Liquido, T. Iwamoto, A. K. Greene, E. A. Jackson, E. M. Pérez, E. Ortí, D. M. Guldi, L. T. Scott, N. Martín Angew. Chem. Int. Ed ., 2014 , 53 , 2170-2175; b) A. de Juan, Y. Pouillon, L. Ruiz-González, A. Torres-Pardo, S. Casado, N. Martín, Á. Rubio, E. M. Pérez Angew. Chem. Int. Ed., 2014 , 53 , 5394-5400; c) H. Isla, E. M. Pérez, N. Martín, Angew. Chem. Int. Ed ., 2014 , 53 , 5629-5633. [3] a) C. Romero.Nieto, R. García, M. A. Herranz, Ch. Ehli, M. Ruppert, A. Hirsch, D. M. Guldi, N. Martín, J. Am. Chem. Soc ., 2012 , 134 , 9183−9192; b) C. Romero-Nieto, R. García, M. A. Herranz, L. Rodríguez-Pérez, M. Sánchez-Navarro, J. Rojo, N. Martín, D. M. Guldi. Angew. Chem. Int. Ed , 2013 , 52 , 10216-10220. [4] J. López-Andarias, J. L. López, C. Atienza, F. G. Brunetti, C. Romero-Nieto, D. M. Guldi, N. Martín, Nat. Commun ., 2014 , DOI: 10.1038/ncomms4763. Figure 1

Yoseph Bar‐Cohen

Encyclopedia of Aerospace Engineering • 2010

Abstract Most biological systems that are larger than a bacteria use muscles as their actuators. Muscles are capable of lifting large loads with short time response in the range of milliseconds but they are driven by a complex mechanism that is very difficult to mimic. Electroactive polymers (EAP) are human made actuators that most closely emulate biological muscles earning them the moniker “artificial muscles”. Initially, EAP received relatively little attention due to their limited actuation capability. In the last twenty years a series of EAP materials have emerged that respond to electrical stimulation with a significant shape change. Using these materials as actuators, various novel mechanisms and devices were already demonstrated including robot fish, miniature gripper, loudspeaker, active diaphragm, catheter steering element,, and dust‐wiper. The impressive advances in improving their actuation strain capability are attracting the attention of engineers and scientists from many different disciplines. These materials are particularly attractive to biomimetic applications allowing for producing biologically inspired intelligent inventions. Increasingly, engineers are able to develop EAP actuated mechanisms that were previously considered science fiction. This chapter reviews the state of the art, challenges, and potential applications of EAP materials to aerospace engineering.

Diana Narvaez, Brittany Newell

Actuators • 2025

Electroactive polymers (EAPs) represent a versatile class of smart materials capable of converting electrical stimuli into mechanical motion and vice versa, positioning them as key components in the next generation of actuators and sensors. This review summarizes recent developments in both electronic and ionic EAPs, highlighting their activation mechanisms, material architectures, and multifunctional capabilities. Representative systems include dielectric elastomers, ferroelectric and conducting polymers, liquid crystal elastomers, and ionic gels. Advances in fabrication methods, such as additive manufacturing, nanocomposite engineering, and patternable electrode deposition, are discussed with emphasis on miniaturization, stretchability, and integration into soft systems. Applications span biomedical devices, wearable electronics, soft robotics, and environmental monitoring, with growing interest in platforms that combine actuation and sensing within a single structure. Finally, the review addresses critical challenges such as long-term material stability and scalability, and outlines future directions toward self-powered, AI-integrated, and sustainable EAP technologies.

Barbar J. Akle, Mike Hickner, Donald J. Leo et al.

Aerospace • 2003

A majority of research on ionic polymer transducers has used Nafion™ as the base material. Varying the physical and chemical properties of Nafion is difficult, which limits the understanding and development of ionic transducers. In this study we investigate a novel class of polymers called BPSH (sulfonated poly(arylene ether sulfone)s). The polymers are synthesized by the direct polymerization of sulfonated monomers. This synthetic scheme affords precise control of the amount and the location of ionic groups along the polymar backbone. These polymers differ from Nafion™ in two major ways. First, the concentration of ionic groups on a mass basis is almost double that of standard Nafion™, 1.51 meq/g for BPSH-30 versus 0.91 meq/g for Nafion™ 1100. Also, the backbone of the BPSH copolymers is much stiffer than Nafion, which affords a higher modulus material. Both of these factors, ion content and modulus, are expected to affect the performance of polymer-based actuators. Another ionomer characterized is the PATS (poly(arylene thiother sulfone)s) which is similar to BPSH. For both polymers we are varying the ionic concentration, stiffness, and water content. Those variations are fostering the understanding of operating concepts of ionic transducers, especially the correlation between ionic transducers, especially the correlation between ionic concentration and performance. Experiments on BPSH-35 demonstrate improved performance as compared to Nafion™ They provide larger strain per unit volt, larger force generated, and larger bandwidth. The novel polymers are characterized as sensors and actuators.

Chen Ang, Zhi Yu

Applied Physics Letters • 2005

The dielectric spectra of poly(vinylidene fluoride-trifluoroethylene) copolymers and poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymers are studied in a wide temperature and frequency range with electric field. It is found that the dominant relaxation process displays a peculiar characteristic—a “dielectric relaxor” behavior, rather than a “ferroelectric relaxor” behavior reported in the current literature; furthermore, we show the experimental observation that the existence of nanometer scale crystals embedded in an amorphous matrix is the base of the dielectric relaxor behavior and high electroactive performance in these polymers.

Chao-Chin Chang, Yu-Chun Chen, Chang-Ping Yu

Sustainable Environment Research • 2022

Abstract In bioelectrochemical wastewater treatment systems, electrochemically active bacteria (EAB) in the anode can simultaneously treat wastewater and produce electricity via extracellular electron transfer. The anode potential has been reported as one way for selecting EAB; though, conflicting results of the relationship between applied potentials and the performance and community composition of EAB have been reported. In this study, we investigated the cultivation time and applied anode potentials (+0.2, 0, −0.2, and −0.4 V vs. Ag/AgCl) on the performance of current production and the compositions of the microbial community. Our results showed that the applied potentials affected the performance of current production, but the effect was substantially reduced with cultivation time. Particularly, the current gradually increased from negative to positive values with time for the applied anode potential at −0.4 V, implying the anode biofilm shifted from accepting electrons to producing electrons. In addition, principal coordinates analysis results indicated that microbial community compositions became closer to each other after long-term enrichment. Subsequently, principal component analysis demonstrated that systems with applied potentials from +0.2, 0 to −0.2 V and at −0.4 V were, respectively, reclassified into principal component 1 (higher-energy-harvesting group) and principal component 2 (lower-energy-harvesting group), implying in addition to cultivation time, the amount of energy available for bacterial growth is another key factor that influences EAB populations. Overall, this study has demonstrated that the selected cultivation time and the particular anode potentials applied in the study determine whether the applied anode potentials would affect the community and performance of EAB.

Jiaxin Li, Bo Song, Chongchao Yao et al.

Nanomaterials • 2022

Iron-based nanomaterials (NMs) are increasingly used to promote extracellular electron transfer (EET) for energy production in bioelectrochemical systems (BESs). However, the composition and roles of planktonic bacteria in the solution regulated by iron-based NMs have rarely been taken into account. Herein, the changes of the microbial community in the solution by S-doped NiFe2O4 anodes have been demonstrated and used for constructing electroactive consortia on normal carbon cloth anodes, which could achieve the same level of electricity generation as NMs-mediated biofilm, as indicated by the significantly high voltage response (0.64 V) and power density (3.5 W m−2), whereas with different microbial diversity and connections. Network analysis showed that the introduction of iron-based NMs made Geobacter positively interact with f_Rhodocyclaceae, improving the competitiveness of the consortium (Geobacter and f_Rhodocyclaceae). Additionally, planktonic bacteria regulated by S-doped anode alone cannot hinder the stimulation of Geobacter by electricity and acetate, while the assistance of lining biofilm enhanced the cooperation of sulfur-oxidizing bacteria (SOB) and fermentative bacteria (FB), thus promoting the electroactivity of microbial consortia. This study reveals the effect of S-doped NiFe2O4 NMs on the network of microbial communities in MFCs and highlights the importance of globality of microbial community, which provides a feasible solution for the safer and more economical environmental applications of NMs.

Maren Mieseler, Mays N Atiyeh, Hector H Hernandez et al.

Journal of Industrial Microbiology and Biotechnology • 2013

Abstract Biological reduction of perchlorate (ClO4−) has emerged as a promising solution for the removal of perchlorate in contaminated water and soils. In this work, we demonstrate a simple process to enrich perchlorate-reducing microbial communities separately using acetate as electron donor and the municipal aerobic membrane bioreactor sludge as inoculum. Inoculation of cathodes in microbial fuel cells (MFCs) with these enrichments, and further electrochemical enrichment at constant resistance operation of the MFCs, led to perchlorate-reducing biocathodes with peak reduction rates of 0.095 mM/day (2 mg/m2/day). Analysis of the microbial diversity of perchlorate-reducing biocathodes using PCR-DGGE revealed unique community profiles when compared to the denitrifying biocathode communities. More importantly, the total time taken for enrichment of the electroactive communities was reduced from several months reported previously in literature to less than a month in this work.

Bernardino Virdis, Diego Millo, Bogdan C. Donose et al.

RSC Advances • 2016

Electrochemically active microbial biofilms are capable to produce electric current when grown onto electrodes. This work investigates the dynamics of electron transfer inside the biofilm as well as at the biofilm/electrode interface.

Yin Ye, Lu Zhang, Xiaohui Hong et al.

The ISME Journal • 2024

Abstract Bioelectrochemical systems (BESs) exploit electroactive biofilms (EABs) for promising applications in biosensing, wastewater treatment, energy production, and chemical biosynthesis. However, during the operation of BESs, EABs inevitably decay. Seeking approaches to rejuvenate decayed EABs is critical for the sustainability and practical application of BESs. Prophage induction has been recognized as the primary reason for EAB decay. Herein, we report that introducing a competitive species of Geobacter uraniireducens suspended prophage induction in Geobacter sulfurreducens and thereby rejuvenated the decayed G. sulfurreducens EAB. The transcriptomic profile of G. sulfurreducens demonstrated that the addition of G. uraniireducens significantly affected the expression of metabolism- and stress response system-related genes and in particular suppressed the induction of phage-related genes. Mechanistic analyses revealed that interspecies ecological competition exerted by G. uraniireducens suppressed prophage induction. Our findings not only reveal a novel strategy to rejuvenate decayed EABs, which is significant for the sustainability of BESs, but also provide new knowledge for understanding phage–host interactions from an ecological perspective, with implications for developing therapies to defend against phage attack.