Detection and imaging of reactive oxygen species associated with the electrochemical oxygen evolution by hydrodynamic scanning electrochemical microscopy

Iffelsberger, Christian; Raith, Timo; Vatsyayan, Preety; Vyskočil, Vlastimil; Matysik, Frank‐Michael

doi:10.1016/j.electacta.2018.05.115

Cited by 18 publications

(18 citation statements)

References 52 publications

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“…Scanning electrochemical microscopy (SECM) is a powerful tool to spatially and temporally resolve local reactivity at interfaces and has been recently applied to heterogeneous electron transfer at BDD electrodes . Various SECM modes have been used to determine outer sphere reactivity in single crystal and polycrystalline BDD electrodes, collect H 2 O 2 and other ROS as water oxidation products, and determine solvent windows of differently doped and terminated facets . Here, we employ the collection mode of SECM to qualify water oxidation products and how they change with pH and electrolyte.…”

Section: Introductionmentioning

confidence: 99%

Interrogating the Surface Intermediates and Water Oxidation Products of Boron‐Doped Diamond Electrodes with Scanning Electrochemical Microscopy

2019

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Boron‐doped diamond (BDD) electrodes are widely used in electrochemical sensing and water purification owing to their chemical and structural stability under harsh reaction conditions. Water oxidation at BDD electrodes is known to produce reactive oxygen species, but the discharged and surface chemistries involved in these processes have not been studied in depth. Here, we present scanning electrochemical microscopy (SECM) studies of electrogenerated intermediates and products formed on sp2 carbon‐containing BDD electrodes that display stark differences in their reactivity as a function of electrolyte type and pH during water oxidation. The most reactive and abundant species discharged from the electrode were observed at pH 11 in sulfate electrolyte. With the surface interrogation mode of SECM, two kinetically distinct surface intermediates were clearly distinguished, with one forming two orders of magnitude faster than the other but displaying a slower desorption rate. The surface coverage of these species was estimated in the range of 4–7×10−5 mol/cm2 for the first, and 3–4.4×10−5 mol/cm2 for the second one. SECM imaging suggested that regions of increased product evolution have decreased electron transfer kinetics and limited surface sites for intermediate binding. This work establishes methods for studying highly reactive intermediates found in BDD and paves the way for the inspection of other interfaces where solvolysis impacts their reactivity and evolution.

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Section: Introductionmentioning

confidence: 99%

Interrogating the Surface Intermediates and Water Oxidation Products of Boron‐Doped Diamond Electrodes with Scanning Electrochemical Microscopy

2019

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“…Although working in feedback mode with forced convection was principally possible, its application to the SECM electrolyte delivers more obvious advantages when experiments are operated in amperometric [22] or voltammetric [29] substrate generation/tip collection mode. Nevertheless, by showing that no distortions of the imaged structure were observed, feedback mode with forced convection can be applied as a complementary mode to hydrodynamic SG/TC mode without altering the experimental conditions.…”

Section: Resultsmentioning

confidence: 99%

Impacts of Forced Convection Generated via High Precision Stirring on Scanning Electrochemical Microscopy Experiments in Feedback Mode

et al. 2018

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In this study, the effects of forced convection on scanning electrochemical microscopy (SECM) experiments in feedback mode using ferrocenemethanol as redox mediator are presented. Forced convection, which enhances the mass transfer inside the system, was generated via an electrical high precision stirrer integrated into the SECM setup. A thin‐film interdigitated array electrode serving as model substrate was investigated with probe scan curves in z‐direction and SECM imaging in constant height mode utilizing ultramicroelectrodes (UME) with diameters (dprobe) of 25 μm and 12.5 μm. It was found that forced convection increased the overall current during SECM imaging without distorting distinctive features of the imaged structure when working with a 25 μm UME at substrate‐to‐tip distances of 14 μm and 11 μm. Furthermore, the electrochemical contrast was improved under hydrodynamic conditions for a substrate‐to‐tip distance of 11 μm and scan rates of 5 μm s−1, 10 μm s−1, 20 μm s−1 and 40 μm s−1. When further decreasing the gap between the UME and the substrate to 9 μm almost no effects of the forced convection were observed. Consequently, for a 25 μm UME, forced convection led to higher currents and improved performance during SECM experiments in feedback mode at substrate‐to‐tip distances of 14 μm and 11 μm, whereas no effects were observed for a 12.5 μm UME at a distance of 8 μm.

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“…As shown in Figure 2, ferrocenecarboxaldehyde (9) is applied to perform the Aldol condensation with curcumin (10), feruloylacetone (11), and dehydrozingerone (12) to afford ferroceneappended curcumins (13~15). Results in the column chart of Figure 2 depict that stoichiometric factor of curcumin (10, n = 8.2) [22] is almost 2~fold higher than that of feruloylacetone (11, n = 4.8), [23] owing to the contribution of double guaiacol moieties to the antioxidative effect of curcumin (10). However, introduction of ferrocene moiety into either curcumin (10) or half-curcumins (11 and 12) just results in a little increase of stoichiometric factors for 13 (n = 9.5) and 14 (n = 5.7), respectively, and n of 15 (4.7) is even similar to that of 11 (n = 4.8).…”

Section: P E R S O N a L A C C O U N T T H E C H E M I C A L R E C O R Dmentioning

confidence: 99%

“…Reactive oxygen species (ROS) are composed of numerous active substances with oxygen atom composing of single electron, which is able to initiate the oxidation of DNA . Growing evidences strongly suggest that many valid strategies are required to repair damages of DNA and to determine oxidative products from DNA damage caused by ROS . On the other hand, DNA as important biological species provides sensitive material for constructing electrochemical biosensor, which can be applied to estimate the damage level of DNA mediated by various ROS resources .…”

Section: Introductionmentioning

confidence: 99%

“…[8] Growing evidences strongly suggest that many valid strategies are required to repair damages of DNA [9] and to determine oxidative products from DNA damage caused by ROS. [10] On the other hand, DNA as important biological species provides sensitive material for constructing electrochemical biosensor, [11] which can be applied to estimate the damage level of DNA mediated by various ROS resources. [12] As for ferrocene derivatives, one important outcome is able to vary the valence of Fe via electron transferring, and the redox couple of Fe(II)/ Fe(III) in ferrocene is thereby used to control antioxidative property of the molecule.…”

Section: Introductionmentioning

confidence: 99%

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Enhancing Antioxidant Effect against Peroxyl Radical‐Induced Oxidation of DNA: Linking with Ferrocene Moiety!

Liu

2019

The Chemical Record

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As a major member in the family of reactive oxygen species, peroxyl radical is able to abstract hydrogen atom from 4‐position of ribose, leading to the collapse of DNA strand. Thus, inhibiting oxidative stress with exogenous antioxidants acts as a promising strategy to protect the integrity of DNA structure and is thereby suggested to be a pathway against developments of related diseases. Ferrocene as an organometallic scaffold is widely applied in the design of organometallic drugs, and redox of Fe(II)/Fe(III) in ferrocene offers advantage for providing electron to radicals. Presented herein are our ongoing studies on ferrocene‐appended antioxidants, including McMurry reaction applied to construct ferrocifen; Aldol condensation used to prepare ferrocenyl curcumin; Povarov reaction employed to prepare ferrocenyl quinoline; Biginelli reaction used to construct ferrocenyl dihydropyrimidine; Groebke reaction used to synthesize ferrocenyl imidazo[1,2‐a]pyridine; and Passerini three‐component reaction as well as Ugi four‐component reaction applied to synthesize α‐acyloxycarboxamide and bisamide, respectively. It is found that ferrocene moiety is able to enhance antioxidative effect of the aforementioned scaffolds even without the aid of phenolic hydroxyl group. The role of ferrocene in enhancing antioxidative effect can be attributable to trapping radicals, decreasing oxidative potential, and increasing the affinity toward DNA strand. Therefore, ferrocene is worthy to be taken into consideration in the design of drugs in relation to DNA oxidation.

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Detection and imaging of reactive oxygen species associated with the electrochemical oxygen evolution by hydrodynamic scanning electrochemical microscopy

Cited by 18 publications

References 52 publications

Interrogating the Surface Intermediates and Water Oxidation Products of Boron‐Doped Diamond Electrodes with Scanning Electrochemical Microscopy

Interrogating the Surface Intermediates and Water Oxidation Products of Boron‐Doped Diamond Electrodes with Scanning Electrochemical Microscopy

Impacts of Forced Convection Generated via High Precision Stirring on Scanning Electrochemical Microscopy Experiments in Feedback Mode

Enhancing Antioxidant Effect against Peroxyl Radical‐Induced Oxidation of DNA: Linking with Ferrocene Moiety!

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