Photoelectrochemical Scanning Droplet Cell Microscopy (PE‐SDCM)

Kollender, Jan Philipp; Mardare, Andrei Ionut; Hassel, Achim Walter

doi:10.1002/cphc.201200656

Cited by 27 publications

(25 citation statements)

References 41 publications

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“…A detailed description of the SDCM setup and preparation process is given elsewhere. 36 Corrosion potentials were determined from potentiodynamic polarization curves measured in 5 wt% NaCl (p. a., Merck) solution using an Ivium CompactStat potentiostat (Ivium Technologies). The potential range was set to ±250 mV vs. the open circuit potential (OCP) with a scan rate of 5 mV s -1 .…”

Section: Methodsmentioning

confidence: 99%

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Combinatorial Electrodeposition of Cobalt-Copper Material Libraries

Grill

Kollender

Hassel

2016

J. Electrochem. Soc.

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A full cobalt-copper material library was successfully prepared from a single experiment by galvanostatic electrodeposition using a modified Hull cell. X-ray fluorescence spectroscopy (XRF) measurements showed, that a composition gradient of 28-96 at.% copper could be achieved. The change of the surface morphology and topography along the material library was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. X-ray diffraction (XRD) revealed a Vegard-like behavior of the face-centered cubic (fcc) cobalt-copper solid solution, as the lattice constant a can be linearly correlated with the atomic copper ratio. The work function, determined from scanning Kelvin probe (SKP) measurements, was expected to decrease gradually with increasing copper content, but was found to be highest (4.86 eV) for a shiny area within the material library (48-62 at.% Cu), indicating higher nobility. This result was confirmed by localized corrosion potential (E corr ) determinations performed by scanning droplet cell microscopy (SDCM). The unexpected high nobility in work function and E corr for this region go hand in hand with a minimum in surface roughness within the material library.

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Section: Methodsmentioning

confidence: 99%

“…E corr values were determined by means of scanning droplet cell microscopy (SDCM), [36][37][38][39] which allows localized electrochemical measurements on different positions, offering the unique opportunity for a detailed electrochemical mapping.…”

mentioning

confidence: 99%

Combinatorial Electrodeposition of Cobalt-Copper Material Libraries

Grill

Kollender

Hassel

2016

J. Electrochem. Soc.

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“…The construction of such tool requires sputtering of the gold electrode on the optical fibre and the electrical connection was achieved with anodic electrophoretic paint. Another very recent example is the photoelectrochemical scanning droplet cell microscopy (PE-SDCM) that is an upgrade to classical scanning droplet cell obtained by the integration of a light source for local illumination [47][48][49]. While these tools are well characterized, their construction requires either multiple laborious steps or 3D printing, the OF-UME tool described in this work is much easier to fabricate as it requires only the usual equipment and procedures used for a UME fabrication.…”

Section: Oxygen Detection During Photocatalytic Water Oxidation At Timentioning

confidence: 99%

Combined local anodization of titanium and scanning photoelectrochemical mapping of TiO2 spot arrays

Badets

Loget

Garrigue

et al. 2016

Electrochimica Acta

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Localized growth of TiO2 and rapid screening of TiO2 photoelectrochemical properties by scanning electrochemical microscopy (SECM) are described. We report the fabrication and operation of an electrochemical tool comprising a microcapillary and an ultramicroelectrode (Cap-UME) that is used for the local formation of TiO2 microspots. This tip allows the generation of arrays of TiO2 of different physicochemical and catalytic characteristics.Moreover, these results prove that local anodization is an efficient method to obtain TiO2 films with micrometre resolution. The use of a combined optical fibre-ultramicroelectrode (OF-UME) in a SECM configuration may operate in two different detection modes. In the first mode, the array is biased and the OF-UME is used as a scanning light source allowing a photocurrent 2 mapping of the surface. In the second mode, the dual OF-UME system serves simultaneously as a light source and an O2 electrochemical sensor which resolved spatially the photoelectrochemically generated O2 species. A direct correlation between the potentials used to produce TiO2, the photocatalytic properties of the TiO2 spots and the amount of oxygen produced was found, demonstrating the strong potential of these tools for the rapid and convenient mapping of TiO2 array properties on a single surface.

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“…All photoelectrochemical measurements were carried out using a scanning droplet cell microscope (PE-SDCM) due to its capability to locally address a small region/spot on the surface, therefore providing a very good compositional resolution. 34 Strong localization combined with automatic operation in the contact mode via XYZ translation stages allow properties mapping with high reproducibility and efficient time consumption. 37 The main body of the cell was made from a plastic block (Polyoxymethylen) into which three connected channels (1.0 mm in diameter) were drilled.…”

Section: H188mentioning

confidence: 99%

Effect of Different Cobalt Concentrations on Tungsten Trioxide Photoelectrodes for Use in Solar Water Oxidation

Kollender

Mardare

Hassel

2015

J. Electrochem. Soc.

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High throughput screening of photoelectrochemical activity was performed on a WO 3 -CoO thin film combinatorial library using photoelectrochemical scanning droplet cell microscopy. The compositional spread was deposited using co-evaporation of WO 3 and metallic Co followed by thermal oxidation in pure oxygen. The elemental compositional mapping along the library via EDX revealed a total compositional gradient of 29 at%. The microstructure and crystallographic properties were investigated via SEM and XRD. Small cubic grains of WO 3 were identified on the surface for Co contents up to 13 at% while CoO remained amorphous along the entire library in mixture with both cubic and orthorhombic WO 3 . A remarkable peak of photoactivity was identified in a compositional range of 7 to 15 at% Co with current density values in excess of 110 μA cm −2 for an applied potential of 1 V vs. SHE. Surface XPS investigations were used for correlating the bulk and surface composition of the library. In the compositional region corresponding to the maximum photoactivity peak, a constant W/Co atomic ratio was measured on the surface while the corresponding bulk ratio was increasing. This effect could be the result of a mixed contribution from an enhanced electrocatalytic activity for oxygen evolution on the surface and increased bulk radiation absorption. Since more than 100 years fossil fuels are satisfying the vast majority of the world's energy needs. Their current level of consumption is leading to serious environmental problems like inevitable emission of CO 2 into the atmosphere. The ever increasing level of CO 2 concentration in the atmosphere is leading to unfavorable changes in Earth's climate and other environmental concerns. For decrease of consumption of fossil fuels, more and more interest is directed toward renewable energy sources.1,2 Photoelectrochemical energy conversion is an attractive approach for conversion of solar energy into chemical energy.3 It offers potentially a cost-effective way for the production of fuels and energy storage, based on renewable resources.4,5 Photoelectrochemical energy conversion based on semiconducting transition metal oxides 6 like TiO 2 , 7-9 Fe 2 O 3 10-13 and WO 3 14-16 is becoming more and more important due to their high electrochemical stability, low cost and natural abundance. Unfortunately, the requirements imposed by the process of photo-induced water splitting are rather stringent. A useable material must be stable under harsh electrochemical conditions, have adequate positioning of the band edges and an appropriate bandgap, catalytic activity for the oxygen or hydrogen evolution reaction, sufficiently high charge carrier mobility and sufficient diffusion length.17 Given all these requirements, it is extremely unlikely that a single material will be used for practical applications. Most probably, complex materials containing various different elements will be used. Even for ternary or quaternary alloys, a large number of materials must be investigated to find an optimal composit...

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Photoelectrochemical Scanning Droplet Cell Microscopy (PE‐SDCM)

Cited by 27 publications

References 41 publications

Combinatorial Electrodeposition of Cobalt-Copper Material Libraries

Combinatorial Electrodeposition of Cobalt-Copper Material Libraries

Combined local anodization of titanium and scanning photoelectrochemical mapping of TiO2 spot arrays

Effect of Different Cobalt Concentrations on Tungsten Trioxide Photoelectrodes for Use in Solar Water Oxidation

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