Imaging Concentration Profiles of Redox‐Active Species with Nanometric Amperometric Probes: Effect of Natural Convection on Transport at Microdisk Electrodes

Baltes, Norman; Thouin, Laurent; Amatore, Christian; Heınze, Jürgen

doi:10.1002/anie.200352662

Cited by 94 publications

(90 citation statements)

References 32 publications

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“…35,[41][42][43][44][45][46] Since the shear forces have to be measured in a viscous liquid, the signal change upon approach is rather small. Because long integration times have to be used, lateral translation rates are restricted.…”

Section: -25mentioning

confidence: 99%

Soft Stylus Probes for Scanning Electrochemical Microscopy

Cortés‐Salazar

Träuble

et al. 2009

Anal. Chem.

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A soft stylus microelectrode probe has been developed to carry out scanning electrochemical microscopy (SECM) of rough, tilted, and large substrates in contact mode. It is fabricated by first ablating a microchannel in a polyethylene terephthalate thin film and filling it with a conductive carbon ink. After curing the carbon track and lamination with a polymer film, the V-shaped stylus was cut thereby forming a probe, with the cross section of the carbon track at the tip being exposed either by UVphotoablation machining or by blade cutting followed by polishing to produce a crescent moon-shaped carbon microelectrode. The probe properties have been assessed by cyclic voltammetry, approach curves, and line scans over electrochemically active and inactive substrates of different roughness. The influence of probe bending on contact mode imaging was then characterized using simple patterns. Boundary element method simulations were employed to rationalize the distance-dependent electrochemical response of the soft stylus probes.Scanning electrochemical microscopy (SECM) is a scanning probe technique that provides spatially resolved detection of electrochemical and chemical surface reactivity.1,2 Typically, the probe is an amperometric disk-shaped ultramicroelectrode (UME) enclosed in an insulating sheath, e.g. glass. Due to the hemispherical diffusion occurring at the microdisc electrode, a steadystate current can be monitored as a function of the horizontal (x, y) and vertical (z) probe positions. SECM has found many applications ranging from surface reactivity imaging 3-13 to the study of the kinetics of homogeneous and heterogeneous reactions at solid/liquid, gas/liquid, and liquid/liquid interfaces. 14-20 Because the response of a SECM probe can be described by continuum models of mass transport coupled to electrochemical kinetics, quantitative kinetic information can be extracted by comparing experimental and simulated curves in many practically relevant situations. 21-25The response of a SECM probe depends on the surface reactivity of the sample and the distance d between the surface and the active area of the probe electrode. In order to obtain a reactivity image that is not influenced by topography, d must be kept constant. In conventional SECM operations, this is achieved by working on samples with a roughness that is considerably smaller than the radius r T of the UME and by leveling the plane of the sample surface with respect to the x,y-scanning plane of the positioning system. However, this approach becomes inappropriate on rough surfaces of large aspect ratios or when large scan areas (in the mm 2 range) have to be investigated so that leveling becomes a major obstacle. Similar limitations apply when imaging curved samples. This drawback has been recognized for a long time. In the case of a small r T , a constant d can be maintained by combining

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Section: -25mentioning

confidence: 99%

Soft Stylus Probes for Scanning Electrochemical Microscopy

Cortés‐Salazar

Träuble

et al. 2009

Anal. Chem.

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“…For example, Fig. 6 shows scanned images from SECM experiments employing a nano-sized electrode with a diameter of 160 nm [51]. During the measurements, the small tip approached the disk substrate at a constant vertical distance of 5 μm; the electrochemical activity and topology of the substrate were then assessed by scanning using Ru(NH 3 ) 6 2+/3+ as a redox couple.…”

Section: Secm With Nanometer Resolution and Afm-secmmentioning

confidence: 99%

“…As shown in Figs. 6 and 7, a nanometer-sized electrode has been used in SECM, though the measurement was performed on a large biological sample with a length scale of a few tens of micrometers [51]. Scanning nanometer-sized samples such as single nanoparticles or single enzymes remains a challenge, even though the electrochemical activity of such species should be monitored to fully understand the catalyst properties, as described in the previous section.…”

Section: Secm With Nanometer Resolution and Afm-secmmentioning

confidence: 99%

Applications of Scanning Electrochemical Microscopy (SECM) Coupled to Atomic Force Microscopy with Sub-Micrometer Spatial Resolution to the Development and Discovery of Electrocatalysts

Park¹,

Jang²

2016

Journal of Electrochemical Science and Technology

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Development and discovery of efficient, cost-effective, and robust electrocatalysts are imperative for practical and widespread implementation of water electrolysis and fuel cell techniques in the anticipated hydrogen economy. The electrochemical reactions involved in water electrolysis, i.e., hydrogen and oxygen evolution reactions, are complex inner-sphere reactions with slow multi-electron transfer kinetics. To develop active electrocatalysts for water electrolysis, the physicochemical properties of the electrode surfaces in electrolyte solutions should be investigated and understood in detail. When electrocatalysis is conducted using nanoparticles with large surface areas and active surface states, analytical techniques with sub-nanometer resolution are required, along with material development. Scanning electrochemical microscopy (SECM) is an electrochemical technique for studying the surface reactions and properties of various types of electrodes using a very small tip electrode. Recently, the morphological and chemical characteristics of single nanoparticles and bio-enzymes for catalytic reactions were studied with nanometer resolution by combining SECM with atomic force microscopy (AFM). Herein, SECM techniques are briefly reviewed, including the AFM-SECM technique, to facilitate further development and discovery of highly active, cost-effective, and robust electrode materials for efficient electrolysis and photolysis.

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“…Especially in the field of electrocatalysis, SECM is a powerful tool for direct investigations of particles. More details will be found in the literature [174,175]. Most previous studies reported in the literature deal with deposition of clusters on substrates induced by the "jump to contact" method ( Fig.…”

Section: Stm Tip As a Tool For Local Nanostructuringmentioning

confidence: 99%