J. S. Foord

University of Oxford, Oxford, England, United Kingdom

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Publications (130)221.84 Total impact

  • Inga Shpilevaya, John S. Foord
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    ABSTRACT: The electrochemical behaviour of methyl viologen and anthraquinonedisulfonate was studied at electrodes produced from differing forms of diamond, including microcrystalline boron doped diamond, boron doped diamond powder and detonation nanodiamond powder. Two types of electrode pretreatment were employed to produce two dissimilar surface terminations: hydrophobic H-terminated and hydrophilic O-terminated. In the case of methyl viologen, it was found that the reduced neutral molecule adsorbed on all three electrodes if they were hydrogen terminated, but not if they were oxygen terminated. For anthraquinonedisulfonate, no adsorption was found on the solid diamond electrode, although again significant adsorption was noted on the powder electrodes, provided they were hydrogen terminated. The reasons underlying these observations are discussed in terms of hydrophobic and electrostatic interactions and the electrode morphology. The work provides information into the likely occurrence of adsorption and concomitant electrode fouling, which may be experienced in electroanalytical applications using solid and powdered forms of diamond.
    Electroanalysis 09/2014; · 2.82 Impact Factor
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    ABSTRACT: Compared with paraffin oil, the use of ionic liquids as a binder in carbon paste type electrodes was shown to greatly enhance the accumulation of analytes, as illustrated with 17α-ethynylestradiol as a model. The ionic “liquid” n-octyl-pyridinium hexafluorophosphate [C8py][PF6] was most efficient among several ionic liquids investigated. Such preconcentration allowed a [C8py][PF6]-multiwalled carbon nanotubes (MWCNTs) (95 : 5 w/w) composite electrode to be useful for adsorptive stripping voltammetry. Screen-printed electrodes modified with [C8py][PF6]-MWCNTs were developed and were able to achieve high sensitivity during adsorptive stripping voltammetric measurements under optimised conditions.
    Electroanalysis 08/2014; · 2.82 Impact Factor
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    ABSTRACT: The use of nano-carbon paste electrodes for the measurement of Gibbs energies of transfer between oil and aqueous phases is reported. In this method the oil of interest is used as the binder for the nano-carbon paste electrodes and the molecule of interest is dissolved in the organic or aqueous phase. Voltammetry is performed over a period of time and used to monitor the transfer of the molecule between the two phases. The method is illustrated for the transfer of ferrocenemethanol between water and oil using the ferrocenemethanol / ferroceniummethanol (FcCH2OH/FcCH2OH+) redox couple. Three pairs of voltammetric peaks were observed in a 0.1 M KCl solution when the nano-carbon paste electrode was modified by dissolution of FcCH2OH in the binder oil: P1 [E=0.23 V, 0.17 V vs. Ag/AgCl (1 M KCl)], P2 [E=0.36 V, 0.32 V vs. Ag/AgCl (1 M KCl)] and P3 [E=0.55 V, 0.46 V vs. Ag/AgCl (1 M KCl)]. These are assigned to the FcCH2OH species existing in the aqueous solution [FcCH2OH(aq)/FcCH2OH+(aq)], originating in the oil (o) [FcCH2OH(o)/FcCH2OH+(aq)] and to oxidation of adsorbed (ads) material on the nano-carbon [FcCH2OH(ads)] respectively. When supporting electrolyte containing the anions Cl−, NO3− or SCN− was used, an expulsion of the oxidised ferrocene occurred and the difference in midpoint potentials (Emid) between the peaks P1 and P2 observed in these experiments allowed the calculation of the Gibbs energy (ΔG°) of transfer of ferrocenemethanol from water to oil. The average ΔG° value thus obtained was (−12.7±0.2) kJ mol−1. For more hydrophobic anions (X−=PF6−, AsF6−), the electron transfer is coupled to the transfer of the anion into the oil and the ΔG° for the transfer of the ion pair of FcCH2OH+ and X− ions from water to oil was found to be −1.3 and −3.9 kJ mol−1 for PF6− and AsF6− respectively.
    Electroanalysis 12/2013; · 2.82 Impact Factor
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    ABSTRACT: The electrochemical behaviour of carbon paste electrodes prepared using nanocarbon and mineral oil was investigated and the results contrasted with different carbon and carbon pastes electrodes. The composition of carbon paste was studied by performing cyclic voltammetry performed in 0.1 M KCl solution in the presence of 4.0 mM Ru(NH3)6Cl3, a well‐characterized redox system commonly used to test the electrode behaviour. After optimisation of the paste composition, the sensors chosen were tested for the analysis and characterization of three different systems: Ru(NH3)63+/2+, FcCH2OH/FcCH2OH+ and acetaminophen. The ability to obtain high quality voltammetry from the nanocarbon electrode was demonstrated and simulation of the voltammetry allowed the extraction of electrode kinetic parameters with high precision.
    Electroanalysis 11/2013; 25(11):2435. · 2.82 Impact Factor
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    ABSTRACT: The voltammetry of some estrogenic compounds (estradiol, nonylphenol, bisphenol A, ethynylestradiol, estrone, estriol) in aqueous solution at boron doped diamond electrodes is reported. For oxidised (hydrophilic) electrodes electrochemically irreversible kinetics were observed for the diffusing molecules allowing the inference of diffusion coefficients and transfer coefficients. In contrast for hydrogen terminated (hydrophobic) surfaces significant adsorption was observed. A limit of detection of 1–100 µM for the estrogenic compounds was found using the oxidised diamond electrode. Surface modification of the oxidised diamond with nano‐Carbon (so‐called Carbon Black) allowed preconcentration of the target by adsorption onto the Carbon Black prior to analysis and a corresponding reduction of the limit of detection by ca three orders of magnitude to 5–100 nM.
    Electroanalysis 01/2013; 25(11). · 2.82 Impact Factor
  • D. Shin, J. S. Foord, R. G. Egdell, A. Walsh
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    ABSTRACT: Thin films of CuCrO{sub 2} have been grown on Al{sub 2}O{sub 3}(001) substrates by oxygen plasma assisted molecular beam epitaxy. With a substrate temperature of 700 Degree-Sign C or 750 Degree-Sign C, the films showed an unanticipated (015) orientation but at a higher substrate temperature of 800 Degree-Sign C the expected basal (001) orientation predominates. The optical absorption spectrum of CuCrO{sub 2} shows a direct allowed absorption onset at 3.18 eV together with a weak peak at 2.0 eV which is suppressed by Sn doping. This suggests that the low energy peak should be attributed to 3d{yields}3d excitations associated with Cu{sup 2+} defect states rather than excitations localised on Cr{sup 3+}. Valence band X-ray photoemission spectra of (001) and (015) oriented CuCrO{sub 2} are compared with those obtained from polycrystalline samples.
    Journal of Applied Physics 12/2012; 112(11). · 2.21 Impact Factor
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    ABSTRACT: Derivatisation of polystyrene by carbene insertions followed by diazonium coupling permits the introduction of diverse chemical functionality, providing access to materials with similar bulk properties, but in which surface chemical characteristics are systematically varied across a range of surface polarity, hydration and non-bonding interaction behaviour. Protein binding experiments with bovine serum albumin demonstrate that protein adhesion is dependent upon the identity of the surface chemical group, with tert-butyl, hexyl, dimethylamino, amino, and carboxyl modified systems all exhibiting higher levels of binding, while glycol, hydroxyl, and phosphonate give similar or lower levels of binding, relative to the control. This behaviour has been shown to be time dependent, and an approximate trend of protein binding with cheminformatic descriptors %PSA and contact angle was observed.
    New Journal of Chemistry 05/2012; 36(5):1187-1200. · 2.97 Impact Factor
  • Liu B, Hu J, Foord J S
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    ABSTRACT: The use of a zirconia thin layer coating to attach phosphate terminated DNA oligonucleotides to a diamond electrode was explored. This DNA functionalised electrode shows an enhanced redox response to the redox mediator methylene blue, which is quenched in the presence of complementary DNA oligonucleotides, enabling the highly sensitive and selective detection of such species in solution. The study shows that the electrodeposition of zirconia on diamond electrodes can be used as an effective and easily implemented route for surface functionalisation and biosensor fabrication using this electrode material.
    Electrochemistry Communications 01/2012; 19:46-49. · 4.29 Impact Factor
  • Alon Hoffman, John Foord
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    ABSTRACT: A graphical abstract is available for this content
    Physical Chemistry Chemical Physics 06/2011; 13(24):11469-70. · 4.20 Impact Factor
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    ABSTRACT: A novel diamond transparent electrode is constructed by integrating conductive diamond film and transparent conducting metal oxide to combine the superior electrochemical properties of diamond and the electrical conductivity of transparent metal oxide (TCO). Direct growth of diamond on indium tin oxide (ITO) and aluminium doped zinc oxide (AZO) was explored, but X-ray photoelectron spectroscopy measurement reveals that both substrates cannot survive from the aggressive environment of diamond growth even if the latter is regarded as one of the most stable TCO. As a second route, a diamond membrane in silicon frame was prepared by selective chemical etching, and a diamond optically transparent electrode (OTE) was constructed by assembling the diamond membrane on the top of an ITO-coated substrate. The resulting device exhibits a high optical transparency and quasireversible electrochemical kinetics, which are competitive to other diamond OTEs reported previously. Its application in UV-Vis spectroelectrochemical studies on the oxidisation of 4-aminophenol was demonstrated.
    SAGE-Hindawi Access to Research International Journal of Electrochemistry. 01/2011; 7.
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    J. Hu, X. Lu, J. S. Foord
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    ABSTRACT: The preparation of Pt-modified diamond electrodes by electrodeposition is known to be hampered by poor particle adhesion and a lack of uniformity in the spatial distribution of the deposit over the electrode surface. Here we demonstrate the results can be improved significantly if the electrode is given a simple ultrasonic treatment in the presence of diamond powders prior to electrodeposition. An improvement in spatial distribution and a higher Pt dispersion are seen and, especially, a greater Pt particle stability is observed. Application of these Pt modified diamond electrodes in the electrochemical oxidation of hydrogen peroxide is demonstrated.
    Electrochemistry Communications - ELECTROCHEM COMMUN. 01/2010; 12(5):676-679.
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    ABSTRACT: Power ultrasound applied to erosion resistant and mechanically stable free standing highly boron-doped diamond electrodes allows the electrochemical reduction of dioxygen to hydrogen peroxide under conditions of extremely high rates of mass transport and in the presence of cavitation.
    ChemInform 01/2010; 29(51).
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    ABSTRACT: The influence of Sn doping on the growth of In <sub>2</sub> O <sub>3</sub> on Y-stabilized ZrO <sub>2</sub>(100) by oxygen plasma assisted molecular beam epitaxy has been investigated over a range of substrate temperatures between 650 and 900 ° C . The extent of dopant incorporation under a constant Sn flux decreases monotonically with increasing substrate temperature, although the n -type carrier concentration in “overdoped” films grown at 650 ° C is lower than in films with a lower Sn concentration grown at 750 ° C . The small increase in lattice parameter associated with Sn doping leads to improved matching with the substrate and suppresses breakup of the films into square islands observed in high temperature growth of undoped In <sub>2</sub> O <sub>3</sub> on Y-stabilized ZrO <sub>2</sub>(100) . Plasmon energies derived from infrared reflection spectra of Sn-doped films are found to be close to satellite energies in core level photoemission spectroscopy, but for a nominally undoped reference sample there is evidence for carrier accumulation at the surface. This influences both the In  3d core line shape and the intensity of a peak close to the Fermi energy associated with photoemission from the conduction band.
    Journal of Applied Physics 08/2009; · 2.21 Impact Factor
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    ABSTRACT: Thin films of In2O3 have been grown on Y-stabilised ZrO2(100) substrates by oxygen plasma assisted molecular beam epitaxy over a range of substrate temperatures between 650 °C and 900 °C. Growth at 650 °C leads to continuous but granular films and complete extinction of substrate core level structure in X-ray photoelectron spectroscopy. However with increasing substrate temperature the films break up into a series of discrete micrometer sized islands. Both the continuous and the island films have excellent epitaxial relationship with the substrate as gauged by X-ray diffraction and selected area electron diffraction and lattice imaging in high resolution transmission electron microscopy.
    Thin Solid Films 06/2009; · 1.87 Impact Factor
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    ABSTRACT: The widths of the valence bands in the copper (I) delafossites CuGaO2, CuInO2, and CuScO2 have been measured by O K-shell x-ray emission spectroscopy and are compared with previous experimental work on CuAlO2 and CuCrO2. In agreement with recent density-functional theory calculations it is found that the bandwidth decreases in the series CuAlO2>CuGaO2>CuInO2>CuScO2. It is shown that states at the top of the valence band are of dominant Cu 3dz2 atomic character but with significant mixing with O 2p states.
    Physical Review B 01/2009; 80(233105). · 3.66 Impact Factor
  • A. Chatterjee, J. S. Foord
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    ABSTRACT: The electrochemical study of flavines is a challenge using many solid-state electrode materials, since pronounced adsorption effects are observed which have deleterious effects on the recorded observations. In the present work three distinctive types of diamond electrode are employed to measure electrochemical charge transfer to riboflavin. At nanodiamond, it is found that rapid charge-transfer kinetics are observed, between the electrode and an adsorbed layer of around 2 monolayers thickness which rapidly forms at the electrode surface. In contrast, high phase purity microcrystalline diamond electrodes, show little adsorption, enabling solution phase diffusion controlled electrochemistry to be observed. Studies of the pH dependence of the observed electrochemistry are presented, which show results comparable to those observed at dropping mercury electrodes, and electrochemical measurements in the presence of power ultrasound are also described.
    Diamond and Related Materials 01/2009; 18(5):899-903. · 1.71 Impact Factor
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    ABSTRACT: Thin films of In2O3 have been grown on Y-stabilized ZrO2(100) by oxygen plasma assisted molecular beam epitaxy with a substrate temperature of 650 °C. Ordered epitaxial growth was confirmed by high resolution transmission electron microscopy. The position of the valence band onset in the x-ray photoemission spectra of the epitaxial films is found to be inconsistent with the widely quoted value of 3.75 eV for the fundamental bandgap of In2O3 and suggests a revised value of 2.67 eV.
    Applied Physics Letters 03/2008; 92(9):092117-092117-3. · 3.79 Impact Factor
  • Chemistry of Materials - CHEM MATER. 01/2008; 20(14):4551-4553.
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    John Foord, Jing Ping Hu
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    ABSTRACT: Diamond electrodes were prepared by MWCVD, using varying methane-to-hydrogen feedstock ratios to form both micro- and nano-crystalline samples. Although Raman spectroscopy indicated substantial concentrations of non-diamond carbon in the nanodiamond forms, XPS and ELS measurements confirm that the area-averaged concentration of such material in the outer layers is very low. Nonetheless, pronounced electrochemical signatures associated with disordered sp2 carbon phases are detected, at sites which are highly aggregated in the grain boundaries. Potential cycling in nitric acid presents an effective route for the complete removal of sp2 carbon material from the electrodes, but this then leads to the formation, of what electrochemically, are completely inactive nanodiamond phases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    Physica Status Solidi (A) Applications and Materials 08/2006; 203(12):3121 - 3127. · 1.53 Impact Factor
  • Arnab Chatterjee, John Foord
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    ABSTRACT: The electrodeposition of zinc oxide thin films at diamond electrode surfaces has been investigated, using a chemical route whereby the electrochemical reduction of nitrate ion raises the local pH, causing the growth of zinc oxide onto the electrode surface. Growth parameters encompassing variation of solution concentration and temperature, along with the electrode potential, are investigated in order to establish the optimal conditions for electrodeposition. The deposits formed comprise small grain crystalline ZnO material and the deposition rate is dependent on the chemical termination and topography of the electrode surface. Deposition is found to be most rapid if the electrode is oxygen-terminated and occurs preferentially at the edges of the exposed crystal facets in the underlying diamond substrate.
    Diamond and Related Materials 01/2006; 15(s 4–8):664–667. · 1.71 Impact Factor

Publication Stats

586 Citations
221.84 Total Impact Points

Institutions

  • 1987–2014
    • University of Oxford
      • • Chemical Research Laboratory
      • • Department of Chemistry
      • • Physcial and Theoretical Chemistry Laboratory
      • • Department of Materials
      • • Inorganic Chemistry Laboratory
      Oxford, England, United Kingdom
  • 2011
    • Technion - Israel Institute of Technology
      • Schulich Faculty of Chemistry
      H̱efa, Haifa District, Israel
  • 1998
    • Oxford Brookes University
      Oxford, England, United Kingdom
    • University of Cambridge
      • Department of Physics: Cavendish Laboratory
      Cambridge, ENG, United Kingdom
  • 1984–1986
    • University of Southampton
      • • Faculty of Natural and Environmental Sciences
      • • Division of Chemistry
      Southampton, ENG, United Kingdom