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Publications (36)
Carbon materials have a long history of use as electrodes in electrochemistry, from (bio)electroanalysis to applications in energy technologies, such as batteries and fuel cells. With the advent of new forms of nanocarbon, particularly, carbon nanotubes and graphene, carbon electrode materials have taken on even greater significance for electrochem...
This chapter is concerned with electrochemistry at, and of, highly oriented pyrolytic graphite (HOPG), a material that has been studied intermittently for several decades, but which is of enduring interest particularly as a comparison to other types of carbon electrodes. It presents an overview of the field, with a particular focus on recent work t...
A new method for transferring chemical vapor deposition (CVD)-grown monolayer graphene, to a variety of substrates is described. The method makes use of an organic/aqueous biphasic configuration, avoiding the use of any polymeric materials that can cause severe contamination problems. The graphene-coated copper foil sample (on which graphene was gr...
The electron transfer (ET) kinetics of three redox couples in aqueous solution, IrCl62-/3-, Ru(NH3)63+/2+ and Fe(CN)64-/3-, on different grades of highly oriented pyrolytic graphite (HOPG) have been investigated in a droplet-cell setup. This simple configuration allows measurements to be made on a very short time scale after cleavage of HOPG, so as...
The electrochemical (EC) behavior of mechanically exfoliated graphene and highly oriented pyrolytic graphite (HOPG) is studied at high spatial resolution in aqueous solutions using Ru(NH3)63+/2+ as a redox probe whose standard potential sits close to the Fermi level of graphene and graphite. By coupling scanning electrochemical cell microscopy (SEC...
The fabrication and use of a multifunctional electrochemical probe incorporating two independent carbon working electrodes and two electrolyte-filled barrels, equipped with quasi-reference counter electrodes (QRCEs), in the end of a tapered micron-scale pipet is described. This 'quad-probe' (4-channel probe) was fabricated by depositing carbon pyro...
No abstract is available for this publication which is a record of the questions, answers and discussions during the Faraday Discussion meeting at Sheffield in September 2014.
No abstract is available for this publication which is a record of the questions, answers and discussions during the Faraday Discussion meeting at Sheffield in September 2014.
The electrochemical (EC) oxidation of the neurotransmitter, serotonin, at individual single-walled carbon nanotubes (SWNTs) is investigated at high resolution using a novel platform that combines flow-aligned SWNTs with atomic force microscopy, Raman microscopy, electronic conductance measurements, individual SWNT electrochemistry and high-resoluti...
There is a prevailing and widely adopted view that carbon nanotubes, which are finding considerable application in energy, healthcare and electronics applications, are highly (electro)catalytically inert unless modified, doped or defected. By visualizing the electrochemical reduction of oxygen (hydrogen peroxide generation) at high resolution along...
Interest in the controlled chemical functionalization of sp(2) carbon materials using diazonium compounds has been recently reignited, particularly as a means generating a band-gap in graphene. In this study, we demonstrate local diazonium modification of pristine sp(2) carbon surfaces, with high control, down at the micron scale through the use of...
We introduce a multi-probe platform for the investigation of single walled carbon nanotubes (SWNTs) that allows the electrochemical response of an individual SWNT to be mapped at high spatial resolution and correlated directly with the intrinsic electronic and structural properties. With this approach, we develop a detailed picture of the factors c...
Boron doped diamond (BDD) disk ultramicroelectrodes have been used to sense single nanoparticle (NP) electrocatalytic collision events. BDD serves as an excellent support electrode due to its electrocatalytic inactivity and low background currents and thus can be used to detect the electroactivity of a wide range of colliding NPs, with high sensiti...
Scanning electrochemical cell microscopy (SECCM) is a new pipette-based imaging technique purposely designed to allow simultaneous electrochemical, conductance, and topographical visualization of surfaces and interfaces. SECCM uses a tiny meniscus or droplet, confined between the probe and the surface, for high-resolution functional imaging and nan...
Carbon nanotubes have attracted considerable interest for electrochemical, electrocatalytic, and sensing applications, yet there remains uncertainty concerning the intrinsic electrochemical (EC) activity. In this study, we use scanning electrochemical cell microscopy (SECCM) to determine local heterogeneous electron transfer (HET) kinetics in a ran...
The electrochemical properties of the closed ends and sidewalls of pristine carbon nanotube forests are investigated directly using a nanopipet electrochemical cell. Both are shown to promote fast electron transfer, without any activation or processing of the carbon nanotube material required, in contrast to the current model in the literature.
As a new form of carbon, graphene is attracting intense interest as an electrode material with widespread applications. In the present study, the heterogeneous electron transfer (ET) activity of graphene is investigated using scanning electrochemical cell microscopy (SECCM), which allows electrochemical currents to be mapped at high spatial resolut...
Scanning electrochemical cell microscopy (SECCM) is a high resolution electrochemical scanning probe technique that employs a dual-barrel theta pipet probe containing electrolyte solution and quasi-reference counter electrodes (QRCE) in each barrel. A thin layer of electrolyte protruding from the tip of the pipet ensures that a gentle meniscus cont...
The characteristics of three different carbon electrodes, glassy carbon (GC), oxygen-terminated polycrystalline boron-doped diamond (pBDD) and "pristine" carbon nanotube networks (CNTN) as voltammetric sensors for detection of the neurotransmitter serotonin have been investigated. For each electrode, detection sensitivity was determined using cycli...
Lithographically patterned nanowire electrodeposition (LPNE) is a new method for fabricating polycrystalline metal nanowires using electrodeposition. In LPNE, a sacrificial metal (M(1)=silver or nickel) layer, 5-100 nm in thickness, is first vapor deposited onto a glass, oxidized silicon, or Kapton polymer film. A (+) photoresist (PR) layer is then...
The resistance, R, of single gold nanowires was measured in situ during electrooxidation in aqueous 0.10 M sulfuric acid. Electrooxidation caused the formation of a gold oxide that is approximately 0.8 monolayers (ML) in thickness at +1.1 V vs saturated mercurous sulfate reference electrode (MSE) based upon coulometry and ex situ X-ray photoelectro...
We describe the preparation of three types of silver/nickel thermocouples (TCs) based upon electrodeposited wires with diameters at, or just below, 1.0 μm: Type 1wire/thin film TCs consisting of an electrodeposited submicrometer diameter wire and an evaporated metal thin film; Type 2wire-wire TCs consisting of end-butted and electrochemically welde...
We describe the preparation by electrodeposition of arrays of lead telluride (PbTe) nanowires using the lithographically patterned nanowire electrodeposition (LPNE) method. PbTe nanowires had a rectangular cross-section with adjustable width and height ranging between 60-400 nm (w) and 20-100 nm (h). The characterization of these nanowire arrays us...
We describe a procedure for preparing submicron scale silver-nickel thermocouples (TCs) using electrochemical step edge decoration on graphite surfaces. Each fabrication operation produced ensembles of 2-20 TCs with diameters in the 1.0 microm to 500 nm range. These "sub-mum TCs" (SMTCs) produced linear voltage versus temperature output over the ra...
We describe a methodology to perform reliable tunneling spectroscopy in electrochemical media. Sequential in situ tunneling spectra are recorded while the electrochemical potential of the electrode is scanned. Spectroscopic data are presented as conductance maps or conductograms that show the in situ electronic structure of an electrode surface whi...
The grafting of nitrobenzene and bromobenzene onto H-terminated p-Si(111) surfaces in the presence of HF in the aqueous diazonium salt containing solution was investigated by in situ photoluminescence (PL) and ex situ infrared ellipsometric spectroscopy (IR-SE). The PL measurements revealed that the grafting process is faster for nitrobenzene and t...
This present work reports on development of an amperometric immunosensor for the diagnosis of Chagas’ disease using a specific glycoprotein of the trypomastigote surface, which belongs to the Tc85-11 protein family of Trypanosoma cruzi (T. cruzi). An atomically flat gold surface on a silicon substrate and gold screen-printed electrodes were functio...
The use of stiff cantilevers with diamond tips allows us to perform nanoindentations on hard covalent materials such as silicon with atomic force microscopy. Thanks to the high sensitivity in the force measurements together with the high resolution upon imaging the surface, we can study nanomechanical properties. At this scale, the surface deforms,...
This paper aims to demonstrate the high capability of infrared spectroscopic ellipsometry (IRSE) for the characterization of very thin organic films and the organic to inorganic interfaces. It is shown that the detection limit of IRSE facilitates the investigation of ultrathin nitrobenzene (NB) films with monolayer sensitivity. This accounts for su...
We present a new procedure to prepare Pt/Ir probes for electrochemical scanning tunneling microscopy (STM) and spectroscopy applications. We detail the experimental setup and the improvements over previous methods. The probes have been used successfully for measurements of tunneling spectroscopy under electrochemical control, which requires scannin...
