Composition depth profiling of polystyrene/poly(vinyl ethyl ether) blend thin films by angle resolved XPS

Angle resolved XPS (ARXPS) and scanning force microscopy (SFM) are used to study polystyrene/poly(vinyl ethyl ether) 50/50 wt% blend thin films spin cast from toluene solution, as a function of polystyrene molecular weight and film thickness. ARXPS is used to investigate the composition depth profile (CDP) of the blend thin films and SFM to study their surface morphology and miscibility. The CDPs are modelled by an empirical hyperbolic tangent function with three floating parameters. These are determined by non-linear least squares regression, their uncertainties estimated and the curve fit residuals analysed to demonstrate that the hyperbolic tangent CDP is a satisfactory fit to the ARXPS data. Conclusions are drawn regarding the behaviour of the blend thin films as the thickness and polystyrene molecular weight are varied. Flory-Huggins interaction parameters (chi) for the mixtures are calculated based upon the segregation data, and suggest a value of chi = 0.05 to be appropriate for this system. (c) 2009 Elsevier B.V. All rights reserved

Nature of band-gap states in V-doped TiO2 revealed by resonant photoemission

Band-gap states in V-doped TiO2 have been studied by photoemission spectroscopy over a range of photon energies encompassing the Ti 3p and V 3p core thresholds. The states show resonant enhancement at photon energies significantly higher than found for Ti 3d states introduced into TiO2 by oxygen deficiency or alkalimetal adsorbates. This demonstrates that the gap states relate to electrons trapped on dopant V cations rather than host Ti cations

Electron Spectroscopy and Density-Functional Study of "Ferric Wheel" Molecules

The Li-centered "ferric wheel" molecules with six oxo-bridged iron atoms form molecular crystals. We probed their electronic structure by X-ray photoelectron (XPS) and soft X-ray emission spectroscopy (XES), having calculated in parallel the electronic structure of a single "ferric wheel" molecule from first-principles by tools of the density-functional theory, using, specifically, the Siesta method. The Fe local moments were found to be 4 mu_B, irrespective of their mutual orientation. Neighbouring atoms, primarily oxygen, exhibit a noticeable magnetic polarization, yielding effective spin S=5/2 per iron atom, that can get inverted as a "rigid" one in magnetic transitions. Corresponding energy preferences can be mapped onto the Heisenberg model with effective exchange parameter J of about -80 K.Comment: 8 pages with 3 embedded postscript figures; uses elsart.cls; contribution at the E-MRS 2003 Spring Meeting (Strasbourg, June 2003

Enhanced adsorptive properties and pseudocapacitance of flexible Polyaniline-activated carbon cloth composites synthesized electrochemically in a filter-press cell

[EN] Electrochemical polymerization is known to be a suitable route to obtain conducting polymer-carbon composites uniformly covering the carbon support. In this work, we report the application of a filter-press electrochemical cell to polymerize polyaniline (PAni) on the surface of large-sized activated carbon cloth (ACC) by simple galvanostatic electropolymerization of an aniline-containing H2SO4 electrolyte. Flexible composites with different PAni loadings were synthesized by controlling the treatment time and characterized by means of Scanning Electron microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS), physical adsorption of gases, thermogravimetric analysis (TGA), cyclic voltammetry and direct current (DC) conductivity measurements. PAni grows first as a thin film mostly deposited inside ACC micro- and mesoporosity. At prolonged electropolymerization time, the amount of deposited PAni rises sharply to form a brittle and porous, thick coating of nanofibrous or nanowire-shaped structures. Composites with low-loading PAni thin films show enhanced specific capacitance, lower sheet resistance and faster adsorption kinetics of Acid Red 27. Instead, thick nanofibrous coatings have a deleterious effect, which is attributed to a dramatic decrease in the specific surface area caused by strong pore blockage and to the occurrence of contact electrical resistance. Our results demonstrate that mass-production restrictions often claimed for electropolymerization can be easily overcome.This research was funded by Spanish Ministerio de Economia y Competitividad and FEDER funds, (grants MAT2016-76595-R and RYC-2017-23618) and Generalitat Valenciana (grant PROMETEO/2018/087)Quijada, C.; Leite-Rosa, L.; Berenguer, R.; Bou-Belda, E. (2019). Enhanced adsorptive properties and pseudocapacitance of flexible Polyaniline-activated carbon cloth composites synthesized electrochemically in a filter-press cell. Materials. 12(16):1-26. https://doi.org/10.3390/ma12162516S1261216Le, T.-H., Kim, Y., & Yoon, H. (2017). Electrical and Electrochemical Properties of Conducting Polymers. Polymers, 9(12), 150. doi:10.3390/polym9040150Ates, M. (2011). Review study of electrochemical impedance spectroscopy and equivalent electrical circuits of conducting polymers on carbon surfaces. Progress in Organic Coatings, 71(1), 1-10. doi:10.1016/j.porgcoat.2010.12.011Culebras, M., Gómez, C., & Cantarero, A. (2014). Review on Polymers for Thermoelectric Applications. Materials, 7(9), 6701-6732. doi:10.3390/ma7096701Choi, H., & Yoon, H. (2015). Nanostructured Electrode Materials for Electrochemical Capacitor Applications. Nanomaterials, 5(2), 906-936. doi:10.3390/nano5020906Kang, E. (1998). 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Polyaniline-Coated Electro-Etched Carbon Fiber Cloth Electrodes for Supercapacitors. The Journal of Physical Chemistry C, 115(47), 23584-23590. doi:10.1021/jp203852pXinping, H., Bo, G., Guibao, W., Jiatong, W., & Chun, Z. (2013). A new nanocomposite: Carbon cloth based polyaniline for an electrochemical supercapacitor. Electrochimica Acta, 111, 210-215. doi:10.1016/j.electacta.2013.07.226Dong, L., Liang, G., Xu, C., Liu, W., Pan, Z.-Z., Zhou, E., … Yang, Q.-H. (2017). Multi hierarchical construction-induced superior capacitive performances of flexible electrodes for wearable energy storage. Nano Energy, 34, 242-248. doi:10.1016/j.nanoen.2017.02.031Yu, P., Li, Y., Yu, X., Zhao, X., Wu, L., & Zhang, Q. (2013). Polyaniline Nanowire Arrays Aligned on Nitrogen-Doped Carbon Fabric for High-Performance Flexible Supercapacitors. Langmuir, 29(38), 12051-12058. doi:10.1021/la402404aMa, J., Tang, S., Syed, J. A., & Meng, X. (2016). Asymmetric hybrid capacitors based on novel bearded carbon fiber cloth–pinhole polyaniline electrodes with excellent energy density. RSC Advances, 6(86), 82995-83002. doi:10.1039/c6ra16291fTran, H. D., D’Arcy, J. M., Wang, Y., Beltramo, P. J., Strong, V. A., & Kaner, R. B. (2011). The oxidation of aniline to produce «polyaniline»: a process yielding many different nanoscale structures. J. Mater. Chem., 21(11), 3534-3550. doi:10.1039/c0jm02699aSapurina, I., & Stejskal, J. (2008). The mechanism of the oxidative polymerization of aniline and the formation of supramolecular polyaniline structures. Polymer International, 57(12), 1295-1325. doi:10.1002/pi.2476Leary, J. D., Hamouda, F., Mazé, B., & Pourdeyhimi, B. (2015). Preparation of pseudocapacitor electrodes via electrodeposition of polyaniline on nonwoven carbon fiber fabrics. Journal of Applied Polymer Science, 133(16), n/a-n/a. doi:10.1002/app.43315Rivera, F. F., de León, C. P., Nava, J. L., & Walsh, F. C. (2015). The filter-press FM01-LC laboratory flow reactor and its applications. Electrochimica Acta, 163, 338-354. doi:10.1016/j.electacta.2015.02.179Tabti, Z., Ruiz-Rosas, R., Quijada, C., Cazorla-Amorós, D., & Morallón, E. (2014). Tailoring the Surface Chemistry of Activated Carbon Cloth by Electrochemical Methods. ACS Applied Materials & Interfaces, 6(14), 11682-11691. doi:10.1021/am502475vLópez-Bernabeu, S., Ruiz-Rosas, R., Quijada, C., Montilla, F., & Morallón, E. (2016). Enhanced removal of 8-quinolinecarboxylic acid in an activated carbon cloth by electroadsorption in aqueous solution. Chemosphere, 144, 982-988. doi:10.1016/j.chemosphere.2015.09.071Huang, H.-C., Ye, D.-Q., & Huang, B.-C. (2007). Nitrogen plasma modification of viscose-based activated carbon fibers. Surface and Coatings Technology, 201(24), 9533-9540. doi:10.1016/j.surfcoat.2007.04.029Oh, K. W., Kim, S. H., & Kim, E. A. (2001). Improved surface characteristics and the conductivity of polyaniline-nylon 6 fabrics by plasma treatment. Journal of Applied Polymer Science, 81(3), 684-694. doi:10.1002/app.1485Banaszczyk, J., Schwarz, A., De Mey, G., & Van Langenhove, L. (2010). The Van der Pauw method for sheet resistance measurements of polypyrrole-coated para-aramide woven fabrics. Journal of Applied Polymer Science, NA-NA. doi:10.1002/app.32186Qu, L., Tian, M., Zhang, X., Guo, X., Zhu, S., Han, G., & Li, C. (2014). Barium sulfate/regenerated cellulose composite fiber with X-ray radiation resistance. Journal of Industrial Textiles, 45(3), 352-367. doi:10.1177/1528083714534708Volkov, A., Tourillon, G., Lacaze, P.-C., & Dubois, J.-E. (1980). Electrochemical polymerization of aromatic amines. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 115(2), 279-291. doi:10.1016/s0022-0728(80)80332-9Chiang, Y.-C., Lee, C.-Y., & Lee, H.-C. (2007). Surface chemistry of polyacrylonitrile- and rayon-based activated carbon fibers after post-heat treatment. Materials Chemistry and Physics, 101(1), 199-210. doi:10.1016/j.matchemphys.2006.03.007Yang, S., Li, L., Xiao, T., Zheng, D., & Zhang, Y. (2016). Role of surface chemistry in modified ACF (activated carbon fiber)-catalyzed peroxymonosulfate oxidation. Applied Surface Science, 383, 142-150. doi:10.1016/j.apsusc.2016.04.163Xie, Y., Wang, T., Franklin, O., & Sherwood, P. M. A. (1992). X-Ray Photoelectron Spectroscopic Studies of Carbon Fiber Surfaces. Part XVI: Core-Level and Valence-Band Studies of Pitch-Based Fibers Electrochemically Treated in Ammonium Carbonate Solution. Applied Spectroscopy, 46(4), 645-651. doi:10.1366/0003702924125005Cotarelo, M. A., Huerta, F., Quijada, C., Mallavia, R., & Vázquez, J. L. (2006). Synthesis and Characterization of Electroactive Films Deposited from Aniline Dimers. Journal of The Electrochemical Society, 153(7), D114. doi:10.1149/1.2198010Cotarelo, M. A., Huerta, F., Quijada, C., Pérez, J. M., del Valle, M. A., & Vázquez, J. L. (2006). Spectroscopic and Electrochemical Study of the Redox Process of Poly(2,2[sup ʹ]-dithiodianiline). Journal of The Electrochemical Society, 153(11), A2071. doi:10.1149/1.2345586Chen, W.-C., Wen, T.-C., Hu, C.-C., & Gopalan, A. (2002). Identification of inductive behavior for polyaniline via electrochemical impedance spectroscopy. Electrochimica Acta, 47(8), 1305-1315. doi:10.1016/s0013-4686(01)00849-0Bai, B. C., Lee, H.-U., Lee, C. W., Lee, Y.-S., & Im, J. S. (2016). N 2 plasma treatment on activated carbon fibers for toxic gas removal: Mechanism study by electrochemical investigation. Chemical Engineering Journal, 306, 260-268. doi:10.1016/j.cej.2016.07.046Nakajima, T., Harada, M., Osawa, R., Kawagoe, T., Furukawa, Y., & Harada, I. (1989). 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Mixed Surface Reaction and Diffusion-Controlled Kinetic Model for Adsorption at the Solid/Solution Interface. The Journal of Physical Chemistry C, 117(16), 8310-8317. doi:10.1021/jp401571mHu, C.-C., Li, W.-Y., & Lin, J.-Y. (2004). The capacitive characteristics of supercapacitors consisting of activated carbon fabric–polyaniline composites in NaNO3. Journal of Power Sources, 137(1), 152-157. doi:10.1016/j.jpowsour.2004.05.040Zhong, M., Song, Y., Li, Y., Ma, C., Zhai, X., Shi, J., … Liu, L. (2012). Effect of reduced graphene oxide on the properties of an activated carbon cloth/polyaniline flexible electrode for supercapacitor application. Journal of Power Sources, 217, 6-12. doi:10.1016/j.jpowsour.2012.05.086Li, Y., & Chen, C. (2017). Polyaniline/carbon nanotubes-decorated activated carbon fiber felt as high-performance, free-standing and flexible supercapacitor electrodes. Journal of Materials Science, 52(20), 12348-12357. doi:10.1007/s10853-017-1291-3Bhaumik, M., McCrindle, R., & Maity, A. (2013). Efficient removal of Congo red from aqueous solutions by adsorption onto interconnected polypyrrole–polyaniline nanofibres. Chemical Engineering Journal, 228, 506-515. doi:10.1016/j.cej.2013.05.026Boutaleb, N., Benyoucef, A., Salavagione, H. J., Belbachir, M., & Morallón, E. (2006). Electrochemical behaviour of conducting polymers obtained into clay-catalyst layers. An in situ Raman spectroscopy study. European Polymer Journal, 42(4), 733-739. doi:10.1016/j.eurpolymj.2005.10.012Trchová, M., Morávková, Z., Bláha, M., & Stejskal, J. (2014). Raman spectroscopy of polyaniline and oligoaniline thin films. Electrochimica Acta, 122, 28-38. doi:10.1016/j.electacta.2013.10.133Li, H., Wang, J., Chu, Q., Wang, Z., Zhang, F., & Wang, S. (2009). Theoretical and experimental specific capacitance of polyaniline in sulfuric acid. 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Removal of paracetamol on biomass-derived activated carbon: Modeling the fixed bed breakthrough curves using batch adsorption experiments. Chemical Engineering Journal, 279, 18-30. doi:10.1016/j.cej.2015.04.144Ayad, M. M., & El-Nasr, A. A. (2010). Adsorption of Cationic Dye (Methylene Blue) from Water Using Polyaniline Nanotubes Base. The Journal of Physical Chemistry C, 114(34), 14377-14383. doi:10.1021/jp103780

The X-ray photoelectron spectroscopy of surface films formed during the ASTM D-130/ISO 2160 copper corrosion test

This is an Author’s Accepted Manuscript of an article published in Petroleum Science & Technology [Volume 32, Issue 4, 2014 ], available online: http://www.tandfonline.com/10.1080/10916466.2011.588635The surfaces of ISO 2160 copper strips tested in iso-octane with elemental sulfur, aliphatic, cyclic and aromatic thiols, diphenyl sulfide, and diphenyl disulfide individually or in combination were studied using XPS. Aliphatic thiols bonded through the sulfur, whereas elemental sulfur formed a cuprous sulfide layer. Aromatics bonded partially through the sulfur with the rings oriented horizontally due to π orbital interactions, accounting in part for their inhibitory effects in the test. The test rating was not directly related to the sulfur concentration in solution or on the surface, and certain combinations of species resulted in higher levels of sulfur at the surface than found individually

Plasma-generated poly(allyl alcohol) antifouling coatings for cellular attachment

Conformal poly(allyl alcohol) (PAA) coatings were grown on a biomedical grade polyurethane scaffold using pulsed plasma polymerization of the allyl alcohol monomer. The creation of a continuous wave polymer primer layer increases the interfacial adhesion and stability of a subsequent pulsed plasma deposited PAA film. The resulting PAA coatings are strongly hydrophilic and stable following 7 days incubation in biological media. Films prepared through this energyefficient, two-step process promote human dermal fibroblast cell culture, while resisting E. coli biofilm formation

Electronic structure study by means of X-ray spectroscopy and theoretical calculations of the "ferric star" single molecule magnet

The electronic structure of the single molecule magnet system M[Fe(L)2]3*4CHCl3 (M=Fe,Cr; L=CH3N(CH2CH2O)2) has been studied using X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, soft X-ray emission spectroscopy, and density functional calculations. There is good agreement between theoretical calculations and experimental data. The valence band mainly consists of three bands between 2 eV and 30 eV. Both theory and experiments show that the top of the valence band is dominated by the hybridization between Fe 3d and O 2p bands. From the shape of the Fe 2p spectra it is argued that Fe in the molecule is most likely in the 2+ charge state. Its neighboring atoms (O,N) exhibit a magnetic polarisation yielding effective spin S=5/2 per iron atom, giving a high spin state molecule with a total S=5 effective spin for the case of M = Fe.Comment: Fig.2 replaced as it will appear in J. Chem. Phy