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Title: Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

Abstract

The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructuredmore » ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.« less

Authors:
; ;  [1];  [2];  [2];  [3]; ; ;  [4]
  1. SIC, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain)
  2. Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain)
  3. (CIBER-BBN), Monforte de Lemos 3-5 Pabellón 11, E-28029 Madrid (Spain)
  4. MIND-IN"2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain)
Publication Date:
OSTI Identifier:
22594361
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; ATOMIC FORCE MICROSCOPY; COMPARATIVE EVALUATIONS; CRYSTALLIZATION; DEPOSITS; ELECTROCHEMISTRY; ELECTRODES; ELECTRON BEAMS; ELECTRONS; EPOXIDES; INDIUM OXIDES; MOLECULES; MORPHOLOGY; NANOWIRES; SCANNING ELECTRON MICROSCOPY; SILANES; SURFACE AREA; SURFACES; THIN FILMS; TIN OXIDES

Citation Formats

Pruna, R., E-mail: rpruna@el.ub.edu, Palacio, F., López, M., Pérez, J., Mir, M., Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Blázquez, O., Hernández, S., and Garrido, B. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces. United States: N. p., 2016. Web. doi:10.1063/1.4960734.
Pruna, R., E-mail: rpruna@el.ub.edu, Palacio, F., López, M., Pérez, J., Mir, M., Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Blázquez, O., Hernández, S., & Garrido, B. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces. United States. doi:10.1063/1.4960734.
Pruna, R., E-mail: rpruna@el.ub.edu, Palacio, F., López, M., Pérez, J., Mir, M., Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, Blázquez, O., Hernández, S., and Garrido, B. 2016. "Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces". United States. doi:10.1063/1.4960734.
@article{osti_22594361,
title = {Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces},
author = {Pruna, R., E-mail: rpruna@el.ub.edu and Palacio, F. and López, M. and Pérez, J. and Mir, M. and Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina and Blázquez, O. and Hernández, S. and Garrido, B.},
abstractNote = {The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.},
doi = {10.1063/1.4960734},
journal = {Applied Physics Letters},
number = 6,
volume = 109,
place = {United States},
year = 2016,
month = 8
}
  • X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA), surface area measurements, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy were used to examine the surface properties of organosilane-modified smectite-type aluminosilicate clays. Organic modified clays derived from the reactions of montmorillonite (containing 93-95% montmorillonite from a bentonite, <1% quartz, and 4-6% opal CT) with octadecyltrichlorosilane (C{sub 18}H{sub 37}SiCl{sub 3}) and octadecyltrimethoxysilane [C{sub 18}H{sub 37}Si(OMe){sub 3}] are highly hydrophobic. Surface loadings of the modified clays depend on the organosilane and the solvent, and they range from 10 to 25 wt. %. The organic species are probably adsorbed to the outer surfaces andmore » bound to the edges of the clay via condensation with edge-OH groups. Encapsulation of montmorillonite with C{sub 18}H{sub 37}SiCl{sub 3} and C{sub 18}H{sub 37}Si(OMe){sub 3} resulted in hydrophobic coating that acts like a 'cage' around the clay particles to limit diffusion. Basal spacings of the organic modified clays remain at {approx}15 {angstrom} upon heating to 400{sup o}C in N{sub 2}, whereas those of unmodified clays collapse to {approx}10 {angstrom}. A considerable reduction in surface area (by 75-90%) for organic modified clays is observed, which is consistent with the existence of a surface coating. The solvent used can affect the amount of organic silane coated on the clay particles, whereas the difference between the products prepared using C{sub 18}H{sub 37}SiCl{sub 3} and C{sub 18}H{sub 37}Si(OMe){sub 3} in the same solvent is relatively small. The carbon and oxygen K-edge NEXAFS spectroscopy of the modified montmorillonite surfaces showed that surface coatings on the outside of the clay particles exist. The encapsulating system may allow for economical remediation and storage of hazardous materials.« less
  • We have successfully developed electrochemical sensors based on functionalized nanostructured materials for voltammetric analysis of toxic metal ions. Glycinyl-urea self-assembled monolayers on mesoporous silica (Gly-UR SAMMS) was incorporated in carbon paste electrodes for the detection of toxic metal ions such as lead, copper, and mercury based on adsorptive stripping voltammetry (AdSV). The electrochemical sensor yields a linear response at low ppb level of Pb2+ (i.e., 2.5 to 50 ppb) after a 2 minute preconcentration period, with reproducible measurements (%RSD = 3.5, N = 6), and excellent detection limits (at few ppb). By exploiting the interfacial functionality of Gly-UR SAMMS, themore » sensor is selective for the target species, does not require the use of a mercury film, and can be easily regenerated in dilute acid solution. The rigid, open, parallel pore structure, combined with suitable interfacial chemistry of SAMMS, also results in fast analysis times (2-3 minutes). The nanostructured SAMMS materials enable the development of miniature sensing devices that are compact and low-cost, have low-energy-consumption, and are easily integrated into field-deployable units. Keywords: electrochemical sensor, glycinyl-urea, self-assembled monolayer, mesoporous silica, lead, mercury, copper, adsorptive stripping voltammetry.« less
  • A stepwise method is described for the accurately controlled growth of Pt nanoparticles supported on ordered mesoporous carbons (Pt-OMC) by the nanocasting of carbon and metal precursors in the pore channels of mesoporous silicas functionalized with Si-H groups. Results obtained from N{sub 2} adsorption/desorption isotherms and transmission electron microscopy showed well-dispersed Pt nanoparticles (2-3 nm) on Pt-OMC with high surface area (837 m{sup 2} g{sup -1}) and regular pore channels (2.9 nm), which facilitate reactant/product diffusion. X-ray diffraction and X-ray photoelectron spectroscopy indicated that Pt nanoparticles in the Pt-OMC sample were mostly present in the metallic form of a face-centeredmore » cubic (fcc) crystalline structure. The Pt-OMC catalyst was found to have superior electrocatalytic properties during oxygen reduction reaction as compared to typical commercial electrocatalysts. - Graphical abstract: A novel procedure has been developed to synthesize ordered carbon mesoporous carbons (OMC) containing well-dispersed and highly electrocatalytic Pt nanoparticles (Pt-OMC) for oxygen reduction reaction. Highlights: > A novel method to incorporate nanosized Pt particles on nanostructure carbons. > Functionalized silica templates were used to control size and distribution of Pt nanoparticles. > Electrochemical measurements of oxygen reduction demonstrated high catalytic activity compared to common commercial catalysts.« less