Versatile DIY Route for Incorporation of a Wide Range of Electrode Materials into Rotating Ring Disk Electrodes

Tully, Joshua J.; Zhang, Zhaoyan; Rodríguez, Irina Terrero; Butcher, Lee; Macpherson, Julie V.

doi:10.1021/acs.analchem.2c01744

Cited by 8 publications

(13 citation statements)

References 40 publications

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“…Effectively, our method dramatically simplifies the estimation and comparative analysis of • OH by replacing the need for ESR measurements in exchange for a swift, inexpensive electrochemical collection approach. Indeed, although we decided to use SECM because of its steady-state and imaging capabilities, short time scale for species detection, and previous experience in our laboratory with methods for ROS detection, there is no reason why the presented methodology cannot be deployed using other techniques such as the rotating ring-disk electrode (RRDE), provided a suitable disk electrode is available . Many laboratories in countries with limited resources may not have ESR instrumentation available, but it is common to find well-established electrochemical facilities elsewhere.…”

Section: Discussionmentioning

confidence: 99%

“…The computed APR values are referenced to the standard hydrogen electrode (SHE) and subsequently referenced to the silver chloride reference electrode (Ag|AgCl). We applied two commonly used SHE reference potentials of 4.28 V and 4.44 V (IUPAC). − In addition to different methods for redox potential prediction, we also employed two different solvation methods to determine the optimum E ° prediction: (1) Polarizable Continuum Model (PCM) using the integral equation formalism variant (IEF-PCM); (2) Solvation Model based on Density (SMD) …”

Section: Methodsmentioning

confidence: 99%

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Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy

et al. 2022

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The hydroxyl radical (•OH) is one of the most attractive reactive oxygen species due to its high oxidation power and its clean (photo)(electro)generation from water, leaving no residues and creating new prospects for efficient wastewater treatment and electrosynthesis. Unfortunately, in situ detection of •OH is challenging due to its short lifetime (few ns). Using lifetime-extending spin traps, such as 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to generate the [DMPO–OH]• adduct in combination with electron spin resonance (ESR), allows unambiguous determination of its presence in solution. However, this method is cumbersome and lacks the necessary sensitivity and versatility to explore and quantify •OH generation dynamics at electrode surfaces in real time. Here, we identify that [DMPO–OH]• is redox-active with E 0 = 0.85 V vs Ag|AgCl and can be conveniently detected on Au and C ultramicroelectrodes. Using scanning electrochemical microscopy (SECM), a four-electrode technique capable of collecting the freshly generated [DMPO–OH]• from near the electrode surface, we detected its generation in real time from operating electrodes. We also generated images of [DMPO–OH]• production and estimated and compared its generation efficiency at various electrodes (boron-doped diamond, tin oxide, titanium foil, glassy carbon, platinum, and lead oxide). Density functional calculations, ESR measurements, and bulk calibration using the Fenton reaction helped us unambiguously identify [DMPO–OH]• as the source of redox activity. We hope these findings will encourage the rapid, inexpensive, and quantitative detection of •OH for conducting informed explorations of its role in mediated oxidation processes at electrode surfaces for energy, environmental, and synthetic applications.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy

et al. 2022

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“…The data suggested that quantification of the true concentration of OH · generated from water oxidation via EC-EPR is problematic. The use of different cell geometries, such as flow cells and/or rotating disk electrodes, could be beneficial to minimize fouling events and prevent further oxidation of DMPO-OH · , as the product is swept away from the electrode surface. Further investigations are required.…”

Section: Discussionmentioning

confidence: 99%

Electron Paramagnetic Resonance for the Detection of Electrochemically Generated Hydroxyl Radicals: Issues Associated with Electrochemical Oxidation of the Spin Trap

et al. 2022

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For the detection of electrochemically produced hydroxyl radicals (HO • ) from the oxidation of water on a boron-doped diamond (BDD) electrode, electron paramagnetic resonance spectroscopy (EPR) in combination with spin trap labels is a popular technique. Here, we show that quantification of the concentration of HO • from water oxidation via spin trap electrochemical (EC)-EPR is problematic. This is primarily due to the spin trap oxidizing at potentials less positive than water, resulting in the same spin trap-OH • adduct as formed from the solution reaction of OH • with the spin trap. We illustrate this through consideration of 5,5-dimethyl-1-pyrroline Noxide (DMPO) as a spin trap for OH • . DMPO oxidation on a BDD electrode in an acidic aqueous solution occurs at a peak current potential of +1.90 V vs SCE; the current for water oxidation starts to rise rapidly at ca. +2.3 V vs SCE. EC-EPR spectra show signatures due to the spin trap adduct (DMPO-OH • ) at potentials lower than that predicted thermodynamically (for water/HO • ) and in the region for DMPO oxidation. Increasing the potential into the water oxidation region, surprisingly, shows a lower DMPO-OH • concentration than when the potential is in the DMPO oxidation region. This behavior is attributed to further oxidation of DMPO-OH • , production of fouling products on the electrode surface, and bubble formation. Radical scavengers (ethanol) and other spin traps, here N-tert-butyl-αphenylnitrone, α-(4-pyridyl N-oxide)-N-tert-butylnitrone, and 2-methyl-2-nitrosopropane dimer, also show electrochemical oxidation signals less positive than that of water on a BDD electrode. Such behavior also complicates their use for the intended application.

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“…After laser cutting, the electrodes were acid cleaned in a boiling mixture of concentrated sulfuric acid (H 2 SO 4 , >96%, Merk) and potassium nitrate (KNO 3 , 99.97%, Sigma-Aldrich) using a procedure described elsewhere. 31 After cleaning, a bilayer ohmic metal contact (Ti 10 nm/Au 400 nm) was deposited onto the lapped (nucleation) surface using a Moorfield MiniLab sputter system. After deposition, this contact was annealed at 400 °C in air for 5 h. 31 Thin film BDD was also used in these studies (Condias GmbH, Germany; DIACHEM) consisting of a ∼10 μm thick layer of BDD supported on an 8 mm diameter niobium substrate and was used as received.…”

Section: Bdd Materialsmentioning

confidence: 99%

“…31 After cleaning, a bilayer ohmic metal contact (Ti 10 nm/Au 400 nm) was deposited onto the lapped (nucleation) surface using a Moorfield MiniLab sputter system. After deposition, this contact was annealed at 400 °C in air for 5 h. 31 Thin film BDD was also used in these studies (Condias GmbH, Germany; DIACHEM) consisting of a ∼10 μm thick layer of BDD supported on an 8 mm diameter niobium substrate and was used as received. SEM and WLI of this BDD surface can be found in Figures 1c−e and SI.2, respectively.…”

Section: Bdd Materialsmentioning

confidence: 99%

Quantitative Measurement Technique for Anodic Corrosion of BDD Advanced Oxidation Electrodes

Tully,

Houghton,

Breeze

et al. 2024

ACS Meas. Sci. Au

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Electrochemical advanced oxidation (EAO) systems are of significant interest due to their ability to treat a wide range of organic contaminants in water. Boron doped diamond (BDD) electrodes have found considerable use in EAO. Despite their popularity, no laboratory scale method exists to quantify anodic corrosion of BDD electrodes under EAO conditions; all are qualitative using techniques such as scanning electron microscopy, electrochemistry, and spectroscopy. In this work, we present a new method which can be used to quantify average corrosion rates as a function of solution composition, current density, and BDD material properties over relatively short time periods. The method uses white light interferometry (WLI), in conjunction with BDD electrodes integrated into a 3D-printed flow cell, to measure three-dimensional changes in the surface structure due to corrosion over a 72 h period. It is equally applicable to both thin film and thicker, freestanding BDD. A further advantage of WLI is that it lends itself to large area measurements; data are collected herein for 1 cm diameter disk electrodes. Using WLI, corrosion rates as low as 1 nm h −1 can be measured. This enables unequivocal demonstration that organics in the EAO solution are not a prerequisite for BDD anodic corrosion. However, they do increase the corrosion rates. In particular, we quantify that addition of 1 M acetic acid to 0.5 M potassium sulfate results in the average corrosion rate increasing ∼60 times. In the same solution, microcrystalline thin film BDD is also found to corrode ∼twice as fast compared to freestanding polished BDD, attributed to the presence of increased sp 2 carbon content. This methodology also represents an important step forward in the prediction of BDD electrode lifetimes for a wide range of EAO applications.

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Versatile DIY Route for Incorporation of a Wide Range of Electrode Materials into Rotating Ring Disk Electrodes

Cited by 8 publications

References 40 publications

Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy

Real-Time Detection of Hydroxyl Radical Generated at Operating Electrodes via Redox-Active Adduct Formation Using Scanning Electrochemical Microscopy

Electron Paramagnetic Resonance for the Detection of Electrochemically Generated Hydroxyl Radicals: Issues Associated with Electrochemical Oxidation of the Spin Trap

Quantitative Measurement Technique for Anodic Corrosion of BDD Advanced Oxidation Electrodes

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