Concurrent nanoscale surface etching and SnO₂ loading of carbon fibers for vanadium ion redox enhancement

• Jun Maruyama,
• Shohei Maruyama,
• Tomoko Fukuhara,
• Toru Nagaoka and
• Kei Hanafusa

Beilstein J. Nanotechnol. 2019, 10, 985–992, doi:10.3762/bjnano.10.99

• TGP-CSnPc-550Air as the negative and positive electrodes, and Nafion 212 as the separator, incorporated into a flow cell similar to that used in a previous study [31]. The number of the layers was also chosen according to the results of this study. TGP-CSnPc-550Air was immersed in ethanol and rinsed

Electrospun one-dimensional nanostructures: a new horizon for gas sensing materials

• Muhammad Imran,
• Nunzio Motta and
• Mahnaz Shafiei

Beilstein J. Nanotechnol. 2018, 9, 2128–2170, doi:10.3762/bjnano.9.202

First examples of organosilica-based ionogels: synthesis and electrochemical behavior

• Andreas Taubert,
• Ruben Löbbicke,
• Barbara Kirchner and
• Fabrice Leroux

Beilstein J. Nanotechnol. 2017, 8, 736–751, doi:10.3762/bjnano.8.77

• interesting for intermediate temperature fuel cells operating above ca. 80 °C. At this point, conventional Nafion membranes dry out and lose the ability for proton conduction [9]. Due to their relatively high thermal stability, high ionic conductivity, and low vapor pressure, many ILs can overcome this

Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions

• Santiago D. Solares

Beilstein J. Nanotechnol. 2016, 7, 554–571, doi:10.3762/bjnano.7.49

Comprehensive characterization and understanding of micro-fuel cells operating at high methanol concentrations

• Aldo S. Gago,
• Juan-Pablo Esquivel,
• Neus Sabaté,
• Joaquín Santander and
• Nicolas Alonso-Vante

Beilstein J. Nanotechnol. 2015, 6, 2000–2006, doi:10.3762/bjnano.6.203

• fuel concentrations. Using 20 M CH3OH causes a loss in performance in the passive µDMFC of 75% as compared to 4 M. It is thus clear that this system suffers from two problems: the Nafion® in the membrane electrode assembly (MEA), which is permeable to the fuel and the lack of tolerance of the cathode

• electrode catalyst takes to get flooded and the catalyst to get eventually poisoned by the fuel that diffuses through the Nafion® membrane of the MEA, the so-called “fuel crossover” effect [32]. The highest open circuit voltage (OCV) is attained only a few seconds after the fuel is added. The cathode

• ®) was put between the Si current collectors, leaving an exposed active area of 0.29 mm2. According to the provider the catalysts mass loading of the anode Pt–Ru/C, and at that of the cathode Pt/C is 4 mg·cm−2, and Nafion® 117 is used as membrane. The fuel reservoir was on top of the anode. As fuel, 100

From lithium to sodium: cell chemistry of room temperature sodium–air and sodium–sulfur batteries

• Philipp Adelhelm,
• Pascal Hartmann,
• Conrad L. Bender,
• Martin Busche,
• Christine Eufinger and
• Juergen Janek

Beilstein J. Nanotechnol. 2015, 6, 1016–1055, doi:10.3762/bjnano.6.105

Materials and characterization techniques for high-temperature polymer electrolyte membrane fuel cells

• Roswitha Zeis

Beilstein J. Nanotechnol. 2015, 6, 68–83, doi:10.3762/bjnano.6.8

• here are applicable to other types of HT-PEMFCs as well. Review Materials for HT-PEMFCs Phosphoric-acid-doped polybenzimidazole-type membranes Nafion® (DuPont), the most prominent member of the PFSA membrane group, exhibits an extremly high proton conductivity of up to 0.1 S·cm−1 under fully hydrated

• conditions. This can be explained by the molecular structure of Nafion shown in Figure 1. The polytetrafluoroethylene (Teflon®)-like molecular backbone gives Nafion its mechanical and chemical stability, while the sulfonic acid functional groups (–SO3−H+) provides charge sites for proton transport. Nafion

• polymer chains aggregate and create voids and channels with walls covered by sulfonic acid functional groups. In the presence of water, protons (H+) detach from the sulfonic acid groups and combine with water molecules to form hydronium complexes (H3O+). To function properly, Nafion needs to be 100

Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

• Matthias Augustin,
• Daniela Fenske,
• Ingo Bardenhagen,
• Anne Westphal,
• Martin Knipper,
• Thorsten Plaggenborg,
• Joanna Kolny-Olesiak and
• Jürgen Parisi

Beilstein J. Nanotechnol. 2015, 6, 47–59, doi:10.3762/bjnano.6.6

• , a 10 wt % Nafion®/water solution was purchased from Sigma-Aldrich, analytical reagent-grade ethanol from Fisher Scientific, and Vulcan® XC72R carbon powder was obtained from Cabot. For electrochemical measurements, reagent-grade lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) was purchased from

• powder with 10 mg of MnOx catalyst. This active material was dispersed in ethanol and ultrasonicated for 20 min. As a binder material, 0.1 wt % Nafion/water solution was added to the catalyst/carbon paste and ultrasonicated for another 20 min. A 10 µL drop of the ink was applied on a glassy carbon disc

Modeling viscoelasticity through spring–dashpot models in intermittent-contact atomic force microscopy

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 2149–2163, doi:10.3762/bjnano.5.224

• dissipation loop, and both curves are smooth with no discontinuity artifacts as for the Linear Kelvin–Voigt model. Nafion® model The Nafion model was introduced by Boyce and coworkers [31] to mimic the behavior of the Nafion proton exchange polymer in biaxial loading tests. This model, shown in Figure 3e

• , consists of a standard linear fluid element (a Linear Maxwell arm in parallel with a dashpot) in series with a spring and in parallel with an equilibrium spring. The special arrangement in this model attempts to reproduce the molecular and intermolecular rearrangement that Nafion undergoes during the

• that nonlinear elements should be present to account for the geometrical aspects of the changing tip–sample contact area during impact. A stress relaxation simulation of the Nafion model is shown in Figure 3f. The inset clearly indicates the presence of two relaxation times in the force–log time curve

Liquid fuel cells

• Grigorii L. Soloveichik

Beilstein J. Nanotechnol. 2014, 5, 1399–1418, doi:10.3762/bjnano.5.153

• sulfonated fluoropolymers such as Nafion® 117 [7] that are stable and conductive up to 85–90 °C. Composite membranes based on both fluorinated and non-fluorinated materials, e.g., polysulfone polymers and inorganic proton conductors are used to achieve higher operating temperatures and a lower humidity [8

• achieved with Ptn(SnO2)/C (n = 1, 3, 9) electrocatalysts. A fuel cell using 2 M EtOH, a Nafion® 117 membrane and a Pt/C cathode catalyst reached a peak power density of 127 mW/cm2 for n = 3 at 100 °C [69]. Acetaldehyde and acetic acid were the major products, and the yield of CO2 was below 7%. Acetic acid

• poisoning, another approach is to increase the operation temperature. To this end, a composite silica/Nafion® membrane was used at 145 °C to reach a maximum power density 110 mW/cm2 with 1 M EtOH feed [70]. Under these conditions CO2 becomes the major product along with a smaller amount of acetaldehyde

Trade-offs in sensitivity and sampling depth in bimodal atomic force microscopy and comparison to the trimodal case

• Babak Eslami,
• Daniel Ebeling and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1144–1151, doi:10.3762/bjnano.5.125

• experiments on Nafion® proton exchange membranes and numerical simulations illustrating the trade-offs between the optimization of compositional contrast and the modulation of tip indentation depth in bimodal atomic force microscopy (AFM). We focus on the original bimodal AFM method, which uses amplitude

• ; multifrequency atomic force microscopy; indentation depth modulation; Nafion; open loop; proton exchange membranes; trimodal; Introduction Since its invention in the early 1980s [1], atomic force microscopy (AFM) has become one of the most widely used characterization tools in nanotechnology and a wide range of

• addition to the noncontact forces. Figure 1 provides an example of single-mode attractive and repulsive images of a Nafion® fuel cell membrane (these images were acquired by using the standard amplitude modulation method [14]). A difference between the two images can be seen in terms of contrast inversion

A catechol biosensor based on electrospun carbon nanofibers

• Dawei Li,
• Zengyuan Pang,
• Xiaodong Chen,
• Lei Luo,
• Yibing Cai and
• Qufu Wei

Beilstein J. Nanotechnol. 2014, 5, 346–354, doi:10.3762/bjnano.5.39

• carbonization technique. And a polyphenol biosensor was fabricated by blending the obtained CNFs with laccase and Nafion. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscope (FE-SEM) were, respectively, employed to investigate the structures and

• hydrogen peroxide (H2O2) [29]. Based on this, laccase has been utilized to fabricate a variety of biosensors, including biosensors for phenolic compounds [30]. Nafion, a linear perfluorosulfonate polymer possesses good cation-exchange properties, biocompatibility and film-forming properties and has been

• widely applied in the fields of fuel cells and sensors [31][32]. In the present work, we prepared ECNFs by carbonizing electrospun PAN nanofibers, and a novel catechol biosensor was fabricated through dropping a mixture solution made of ECNFs, laccase and Nafion on a processed glass-like-carbon electrode

Constant-distance mode SECM as a tool to visualize local electrocatalytic activity of oxygen reduction catalysts

• Michaela Nebel,
• Thomas Erichsen and
• Wolfgang Schuhmann

Beilstein J. Nanotechnol. 2014, 5, 141–151, doi:10.3762/bjnano.5.14

• recessed electrodes have already been reported [33][34] and a further miniaturization of the modified surface area is therefore possible. Furthermore, immobilization of the catalyst powder within the cavity of the recessed microelectrode allows for avoiding any binder additive such as, e.g., Nafion that is

• commonly used for rotating disk electrode studies or spot preparation [23]. Since the influence of Nafion on the catalytic activity is still not fully understood [35][36][37], the investigation of the catalyst material in absence of any binder is an additional advantage of this sample preparation method

• (Sigradur G, 1 mm thickness, HTW, Thierhaupten, Germany). 1 mL of the catalyst suspension consisted of 2.5 mg catalyst powder in a solution of 49.5% ethanol, 49.5% water and 1% Nafion (solution of 5 wt % Nafion from Sigma-Aldrich, Steinheim, Germany). The spot was prepared by 3200 droplets dispensing 45 pL

Design criteria for stable Pt/C fuel cell catalysts

• Josef C. Meier,
• Carolina Galeano,
• Ioannis Katsounaros,
• Jonathon Witte,
• Hans J. Bongard,
• Angel A. Topalov,
• Claudio Baldizzone,
• Stefano Mezzavilla,
• Ferdi Schüth and
• Karl J. J. Mayrhofer

Beilstein J. Nanotechnol. 2014, 5, 44–67, doi:10.3762/bjnano.5.5

AFM as an analysis tool for high-capacity sulfur cathodes for Li–S batteries

• Renate Hiesgen,
• Seniz Sörgel,
• Rémi Costa,
• Linus Carlé,
• Ines Galm,
• Natalia Cañas,
• Brigitta Pascucci and
• K. Andreas Friedrich

Beilstein J. Nanotechnol. 2013, 4, 611–624, doi:10.3762/bjnano.4.68

• nickel layer or by coating with Nafion [15][16]. To obtain a superior capacity and reversible cycle performance, the production of thin and porous sulfur cathodes or the use of foam-like structures as current collectors have been shown to be advantageous [9][17][18]. Recent studies have shown that the

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

• Pavel V. Komarov,
• Pavel G. Khalatur and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2013, 4, 567–587, doi:10.3762/bjnano.4.65

• Department, Moscow State University, Moscow 119991, Russia 10.3762/bjnano.4.65 Abstract Atomistic and first-principles molecular dynamics simulations are employed to investigate the structure formation in a hydrated Nafion membrane and the solvation and transport of protons in the water channel of the

• membrane. For the water/Nafion systems containing more than 4 million atoms, it is found that the observed microphase-segregated morphology can be classified as bicontinuous: both majority (hydrophobic) and minority (hydrophilic) subphases are 3D continuous and organized in an irregular ordered pattern

• hindered translational motions of cations reveal that ion association observed with decreasing temperature is largely an entropic effect related to the loss of low-frequency modes. Based on the results from the atomistic simulation of the morphology of Nafion, we developed a realistic model of ion

Novel composite Zr/PBI-O-PhT membranes for HT-PEFC applications

• Mikhail S. Kondratenko,
• Igor I. Ponomarev,
• Marat O. Gallyamov,
• Dmitry Y. Razorenov,
• Yulia A. Volkova,
• Elena P. Kharitonova and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2013, 4, 481–492, doi:10.3762/bjnano.4.57

• an optimal balance of these properties. In order to enhance the mechanical strength, various polymers, such as PTFE [2][3] or polymer sulfonic acids, which can form ionic bonds with basic PBI (Nafion [4], SPEEK [5][6]), were proposed as functional fillers for PBI membranes. Even carbon nanotubes were

Distribution of functional groups in periodic mesoporous organosilica materials studied by small-angle neutron scattering with in situ adsorption of nitrogen

• Monir Sharifi,
• Dirk Wallacher and
• Michael Wark

Beilstein J. Nanotechnol. 2012, 3, 428–437, doi:10.3762/bjnano.3.49

• generated H2 from the simultaneously formed O2 [31][32]. Based on functionalized mesoporous silica (e.g., Si-MCM-41-SO3H) and different polymer materials (e.g., Nafion® or polysiloxanes) such hybrid membranes have already been realized [28][29]; PMOs, however, may be superior compared to MCM-41 due to their

Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

• Sushil Kumar and
• Victoria Vicente-Beckett

Beilstein J. Nanotechnol. 2012, 3, 388–396, doi:10.3762/bjnano.3.45

• carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA) by square-wave

• ends of the CNTs have been observed to produce relatively low peak potentials and high peak currents in the voltammetry of several electroactive molecules at electrodes modified with CNTs [14][15]. Nafion, a perfluorosulfonated polymer with cation-exchange properties, has been used to stably confine

• this study for the development of the analytical method for AA analysis. GCE surface modification The effect of using an increasing concentration of MWCNTs in 0.1% (w/v) Nafion solution to modify the GCE is depicted in the voltammograms of 1 mmol/L AA in 0.1 M acetate buffer presented in Figure 2. The

Schottky junction/ohmic contact behavior of a nanoporous TiO₂ thin film photoanode in contact with redox electrolyte solutions

• Masao Kaneko,
• Hirohito Ueno and
• Junichi Nemoto

Beilstein J. Nanotechnol. 2011, 2, 127–134, doi:10.3762/bjnano.2.15

• . This is composed of three layers, i.e., [carbon paper/Pt–carbon catalyst-dispersed Nafion 117 (sulfonated perfluoroalkyl cation exchange polymer) membrane/Pt–carbon catalyst-dispersed carbon paper], for which the first layer is in contact with the electrolytes liquid, and the last layer is exposed to