Boron-doped Diamond Electrode Research Articles

Synthetic Cathinones' Comprehensive Screening and Classification by Voltammetric and Chemometric Analyses: A Powerful Method for On-Site Forensic Applications.

The use of synthetic cathinones (SCs) has increased in recent years, posing significant public health problems due to their adverse effects and potential for fatal poisonings. The structural diversity and rapid emergence of new SC analogues create challenges for law enforcement and drug screening techniques. This work presents for the first time the electrochemical detection of SCs using differential pulse voltammetry (DPV) on a boron-doped diamond electrode (BDDE). We analyzed 15 SCs, including well-known compounds such as mephedrone, methylone, and ephylone, revealing distinct electrochemical profiles with two characteristic reduction peaks (R1 and R2). The method was optimized in Britton-Robinson buffer (0.1 mol L-1, pH 8.0) and demonstrated a high selectivity and sensitivity. Multivariate statistical methods, including principal component analysis and hierarchical cluster analysis, classified SCs into six distinct groups. The DPV optimization and analytical parameter determination, including the limit of detection (LOD), were performed for the least electroactive SC, 4'-methyl-α-pyrrolidinohexanophenone, yielding an LOD of 3.8 μmol L-1, suitable for screening street samples. Interference studies with common illicit drugs and adulterants confirmed the selectivity of the DPV-BDDE method. Preliminary identification of SCs in 46 real seized samples was successfully performed using this method with results validated by liquid chromatography-mass spectrometry (LC-MS). The method also identified three SCs not included in the original set: bupropion, benzylone, and dipentylone. The DPV-BDDE method offers a rapid, robust, and portable approach for the selective screening of SCs in forensic applications, demonstrating significant advantages over traditional colorimetric tests.

Fabrication of nitrogen-doped quenched-produced diamond electrodes on titanium substrates by coaxial arc plasma deposition

Nitrogen-doped quenched-produced diamond (N-doped Q-dia) thin films were deposited onto a titanium substrate by coaxial arc plasma deposition (CAPD). The N-doped Q-dia thin film was successfully synthesized at room temperature without peeling. Its performance as an electrode material in aqueous solutions was investigated. The overpotential for the hydrogen evolution reaction was 0.35 V higher than the conventional boron-doped diamond (BDD) electrode. The kinetics of reversible electron transfer for redox species were comparable to the BDD electrode. We have demonstrated the N-doped Q-dia thin films have promising potential as a competitive and alternative electrode material to BDD films for electrochemical applications.

Three-dimensional porous SiC/BDD electrode with long-term robustness and enhanced electrochemical degradation performance for refractory organic pollutants

Boron-doped diamond (BDD) electrodes with a three-dimensional (3D) porous network structure can overcome the mass transfer limitations and increase substantially the utilization rate of active oxygen species. Nonetheless, the 3D porous network structure was invariably built using metallic substrates, which inherently have inferior stability because of their non-corrosion resistance and the severe thermal mismatch between BDD films and substrates. Herein, we reported, for the first time, the use of a commercially porous silicon carbide (SiC) as the substrate to construct a 3D SiC/BDD electrode to simultaneously alleviate the problematics of substrate corrosion and thermal mismatch. This novel electrode exhibited a long-term service lifetime of 800 h in 3 M H2SO4 under the current density of 50 mA cm−2, over 500 times longer than the conventional metallic substrate-based BDD electrodes. The optimum p-SiC/BDD electrode exhibited a high oxygen evolution potential of 2.04 V vs. SHE, a low charge transfer resistance of 18.4 Ω, a high mass transfer coefficient of 2.78 × 10−5 m s−1, and a thin diffusion layer thickness of 25.2 μm. The proposed electrode had a threefold larger pseudo-first-order reaction rate constant than a flat BDD electrode, although it consumed just a fourth of the latter’s electric energy. The superior performance was attributable to an increased mass transfer rate confirmed by computational fluid dynamics (CFD) simulations as well as a high yield of reactive oxygen species verified by electron spin resonance (ESR). Furthermore, the proposed SiC/BDD electrode could work effectively under different water matrices in the presence of diverse salt electrolytes, thus paving a new avenue for the structure design of robust non-active anode materials.

Introducing nickel nanoparticles on boron-doped diamond electrode for realizing high performance electrochemical detection of azithromycin

The broad-spectrum antibiotic azithromycin (AZI) has been widely applied to suppress bacteria and fight infection. However, excessive use of AZI can cause serious side effects. It is greatly desirable to develop efficient and sensitive sensor devices for environmental monitoring and analysis of AZI. In this study, we develop the nickel (Ni) nanoparticle-modified boron-doped diamond (NiNPs-BDD) electrode to achieve high-performance electrochemical detection of AZI. The NiNPs-BDD electrode has square pits with Ni particles embedded in the pits, which provides higher sensitivity compared to unmodified BDD. The promoting performance is attributed to the synergistic effect of pitted features and Ni NPs on BDD electrode. The NiNPs-BDD electrode presents linear detection ranges in the wide concentration scales of 0.1–8 µM and 8–100 µM, and its limit of detection is 0.086 µM. In addition, the NiNPs-BDD electrode shows excellent repeatability, stability, and reproducibility with respect to most conventional electrodes.

First Voltammetric Determination of Karbutylate via Pencil Graphite, Glassy Carbon, and Boron-Doped Diamond Electrodes in Soil Sample

We investigated the electrochemical behavior of carbamate pesticide-type karbutylate (KB) with boron-doped diamond (BDD), glassy carbon (GC), and pencil graphite (PG) electrode, and analytical determination in real samples. Similar to organophosphate insecticides, carbamate pesticides are produced from carbamic acid and are extensively utilized in agriculture, gardens, and residences. Therefore, a rapid and simple detection of KB in real samples is important. Carbon-based electrodes are widely used in electroanalytical chemistry due to their rich surface chemistry, chemical inertness, broad potential window, low background current, and congruency for various demanding applications. Three different carbon-based electrodes were used. The effect of buffer solutions, scan rate, square wave (SWV), and differential pulse voltammetry parameters on the voltammetric response of KB was tested. The optimum working media for all three electrodes was determined as pH 2.00 phosphate buffer solution and voltammetric measurements were carried out in this media. Under optimum experimental conditions, linear calibration dependences for KB were obtained as 6.00 × 10−7–8.00 × 10−5 M, 4.00 × 10−7–8.00 × 10−5 M, and 8.00 × 10−8–8.00 × 10−5 M with a limit of detection of 2.18 × 10−7, 3.71 × 10−8 M, and 2.66 × 10−8 M by the BDD, GC, and PG electrodes, respectively, using SWV. As a result, sensitive determination of KB has been successfully performed using different carbon-based electrodes in real soil samples.

Correlation of residual stress on piezoresistive properties of boron-doped diamond films

To investigate the influence of residual stress on the piezoresistive behavior of boron-doped diamond (BDD) films, BDD films with varying doping concentrations were synthesized using a hot-filament chemical vapor deposition (HFCVD) system on silicon and diamond substrates. The relationship between the surface morphology, structural composition, resistivity, and piezoresistive properties of BDD electrodes was examined, along with an in-depth analysis of the impact of boron doping level on these properties. The microstructure and bonding state of the BDD films were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. The piezoresistive properties of the BDD films were evaluated employing a cantilever beam bending method. Our findings demonstrate that the level of boron doping not only affects resistivity but also directly influences residual stress in BDD films, both factors having an impact on their piezoresistive properties. Despite significantly larger grain sizes observed in BDD films grown on diamond substrates compared to those grown on silicon substrates at identical boron doping concentrations, they exhibit consistent variations in residual stress and gauge factor (GF) values. With increasing doping levels, the absolute residual stress decreases initially before increasing again; moreover, at 2000 ppm doping level, it transitions from compressive to tensile stress. The GF value is closely associated with both the magnitude and type of residual stress. By utilizing a doping concentration of 2000 ppm for growth on diamond substrates, we achieved a peak GF value of 257 for BDD films which highlights their promising potential for pressure sensor applications.

Electrochemical Colour Removal of Azo Dyes Using Boron-Doped Diamond Electrodes and Silver Nanoparticles as Electrocatalyst

Electrochemical Colour Removal of Azo Dyes Using Boron-Doped Diamond Electrodes and Silver Nanoparticles as Electrocatalyst

CHARACTERIZATION AND ELECTROCHEMICAL BEHAVIOUR OF BORON DOPED DIAMOND IN DETECTING AMODIAQUINE

Amodiaquine (AQ) is an essential medicine in treating malaria. Yet, the threat of drug resistance and toxicity necessitates accurate measurement of AQ in the human body. This research determines the amodiaquine (AQ) detection performance of boron-doped diamond (BDD) working electrodes. The study utilizes different pulse velocity (DPV) methods to analyze the AQ reaction behavior of BDD. The research demonstrates the reaction mechanism: Two electrons are transferred, and irreversible oxidation reactions occur. The sensor limit of detection (LOD) is measured to determine the performance of working electrodes for AQ detection. The LOD is calculated between 0.0645 µM and 0.3 µM, and changes in analytical concentrations relative to maximum current are calculated. The LOD of the BDD electrode is 1.5×10–8 M, lower than previous research on AQ sensors, showing the effectivity of the BDD electrode as an AQ sensor.

Chemical structure dependent electrochemical degradation of antibiotics using Boron-doped Diamond Electrodes

The electrochemical degradation of Amoxicillin (AMOX), Ciprofloxacin (CIP), and Streptomycin (STR) utilizing Boron-Doped Diamond Electrodes (BDD) was explored under varying levels of applied electrical current density and initial buffer acidity. These pharmaceuticals were carefully selected to showcase the efficiency of electrochemical oxidation across different major chemical structure antibiotic families. The results demonstrated a positive correlation between higher applied current density and the elimination of antibiotics, as well as enhanced chemical oxygen demand (COD) removal rate. However, a negative impact was observed on the specific energy consumption (SEC). Notably, the highest antibiotics and COD removal efficiencies, along with the lowest SEC, were achieved at an applied current density of 45 mA/cm2. Furthermore, the investigation highlighted the significant influence of the chemical structure of the selected antibiotics on their degradation process. At a current density of 15 mA/cm2 and after 24 minutes of treatment, the degradation order was found to be AMOX > CIP > STR, with respective antibiotic removal efficiencies of 98.5 %, 87.8 %, and 81.1 %. Similarly, after 90 minutes of treatment, the COD degradation efficiency followed the order AMOX (50.4 %) > CIP (47.3 %) > STR (44.6 %), accompanied by decreasing levels of specific energy consumption, measuring 59, 61, and 67 kWh/kg COD, respectively, with an average current efficiency of 23–26 %. The pH had a significant effect on the streptomycin degradation rate, while it had a negligible impact on the degradation rate of ciprofloxacin. These findings shed light on the critical role of the pharmaceuticals' chemical structures and environmental conditions in governing the efficiency of their electrochemical degradation.

Sensitive electrochemical sensor of levofloxacin using boron-doped diamond (BDD) electrode modified with Ti3C2TX (MXene) material

Sensitive electrochemical sensor of levofloxacin using boron-doped diamond (BDD) electrode modified with Ti3C2TX (MXene) material

Fast, Simple, and Sensitive Voltammetric Measurements of Acyclovir in Real Samples via Boron-Doped Diamond Electrode.

The voltammetric acyclovir (ACV) trace-level determination procedure has been introduced. This is the first time that a commercially available boron-doped diamond electrode (BDDE) coupled with differential-pulse voltammetry (DPV) has been used for this purpose. The commercially available BDDE is characterized by a short response time, low background current, and very good analytical parameters of ACV determination. Ultimately, DPV measurements using the BDDE in 0.075 mol L-1 PBS with a pH of 7.2 under optimized conditions achieved the lowest detection limit (LOD = 0.0299 nmol L-1) reported in the literature for voltammetric procedures. Moreover, it is highly resistant to the presence of various interfering agents and has been used to analyze pharmaceutical and municipal wastewater samples. The obtained results are consistent with measurements made using chromatographic reference methods.

Interface engineering of laminated redox-copolymers for electrochemical remediation of perfluoroalkyl substances

Redox polymers now show promise for selective removal of perfluoroalkyl substances from a complex aqueous matrix at high energy efficiency and no secondary pollution. However, self-agglomeration of redox polymers is a dominating barrier to constructing a low-cost, stable system in practical applications. Herein, we introduce polymer interface engineering strategy to enhance the activity of amine functionalities and nitrous oxide radicals in copolymers composed of 4-methacryloyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl and 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine. The grafted laminated redox polymer on multi-walled carbon nanotubes (termed MWCNT-g-P(TMPMA-co-TMA)) via free-radical polymerization demonstrated a 19.1–59.9 % increase in the electrosorption capacity with a maximum value (Qm) of 725.09 mg g−1 and a pseudo-first-order rate constant k1 = 1.46 min−1 and sustainable regeneration efficiency at ∼80 %. The core–shell structure of MWCNT-g-P(TMPMA-co-TMA) with a laminated redox polymer layer of ∼5 nm processed a low charge transfer resistance, which is expected to contribute to the enhanced capture performance and stability. An integrated system consisting of a MWCNT-g-P(TMPMA-co-TMA) electrode and a boron-doped diamond electrode can efficiently separate and degrade trace-concentration PFOA from industrial wastewater at high mineralization efficiency. This work provides insight into the design and optimization of redox active materials for water purification and beyond.

Voltammetric and flow amperometric determination of drug guaifenesin in pharmaceutical and biological samples using screen-printed sensor with boron doped diamond electrode

New voltammetric and flow amperometric methods for the determination of guaifenesin (GFE) using a perspective screen-printed sensor (SPE) with boron-doped diamond electrode (BDDE) were developed. The electrochemical oxidation of GFE was studied on the surface of the oxygen-terminated BDDE of the sensor. The GFE provided two irreversible anodic signals at a potential of 1.0 and 1.1 V (vs. Ag|AgCl|KCl sat.) in Britton-Robinson buffer (pH 2), which was chosen as the supporting electrolyte for all measurements. First, a voltammetric method based on differential pulse voltammetry was developed and a low detection limit (LOD = 41 nmol L−1), a wide linear dynamic range (LDR = 0.1–155 μmol L−1), and a good recovery in the analysis of model and pharmaceutical samples (RSD <3.0 %) were obtained. In addition, this sensor demonstrated excellent sensitivity and reproducibility in the analysis of biological samples (RSD <3.2 %), where the analysis took place in a drop of serum (50 μL) without pretreatment and additional electrolyte. Subsequently, SP/BDDE was incorporated into a flow-through 3D printed electrochemical cell and a flow injection analysis method with electrochemical detection (FIA-ED) was developed, resulting in excellent analytical parameters (LOD = 86 nmol L−1, LDR = 0.1–50 μmol L−1). Moreover, the mechanism of electrochemical oxidation of GFE was proposed based on calculations of HOMO spatial distribution and spectroelectrochemical measurements focused on IR identification of intermediates and products.

Study of quinine hydrochloride detection using boron-doped diamond electrodes

This study investigates the electrochemical properties of quinine hydrochloride (QH) using boron-doped diamond (BDD) electrodes. The redox behavior of QH was analyzed and compared in phosphate buffer solution (PBS) and potassium perchlorate (KClO4) electrolyte, observing an increase in current response with hydrogen-terminated BDD (H-BDD) electrodes. A cyclic voltammogram of QH in 0.1 M PBS and 0.1 M KClO4 shows a reduction peak at −1.14 V (vs. Ag/AgCl). The scan rate dependence was examined to understand the reduction mechanism involving two electrons. A linear calibration curve was noted from 2 μM to 25 μM range (R2 = 0.99) with detection limits of 0.18 μM in PBS and 0.16 μM in KClO4. The BDD electrodes demonstrated good selectivity in tonic water with sharp oxidation potentials for QH, confirming their stability for QH detection.

Unusual electrochemical properties of boron and silicon Co-doped diamond electrodes

Boron-doped diamond (BDD) films exhibit exceptional physicochemical properties and have been utilized in numerous fields. As a common impurity in diamond, silicon is inevitably introduced into the diamond lattice during certain growth process. However, there are limited reports on the impact of silicon co-doping on the electrochemical properties of BDD electrodes. In this paper, we prepared a series of BDD electrodes with various silicon contents and made a systematic evaluation of these electrodes in terms of physicochemical properties. The results indicated that silicon and boron co-doped diamond (SiBDD) electrodes displayed a broader potential window and lower background current compared to the pure BDD electrode. Additionally, we observed that the electron transfer rate of the electrodes in the inner ([Fe(CN)6]3−/4−) redox systems exhibited a rising trend with increasing silicon content, whereas the electron transfer rate of the outer ([Ru(NH3)6]3+/2+) redox systems displayed contrasting trend. Surface analyses and electrochemical measurements results suggested that the unusual phenomena might stem from the alterations in surface functional groups and carrier density of the electrode inducing by silicon co-doping. In general, our results demonstrate, for the first time, that Si co-doping can influence the surface functional groups and carrier behavior of BDD electrodes, thereby altering the electrode's electrochemical performance. This provides new insights for the design of high-performance diamond electrodes.

Fluorescence and electron transfer of Limnospira indica functionalized biophotoelectrodes

Cyanobacteria play a crucial role in global carbon and nitrogen cycles through photosynthesis, making them valuable subjects for understanding the factors influencing their light utilization efficiency. Photosynthetic microorganisms offer a promising avenue for sustainable energy conversion in the field of photovoltaics. It was demonstrated before that application of an external electric field to the microbial biofilm or cell improves electron transfer kinetics and, consequently, efficiency of power generation. We have integrated live cyanobacterial cultures into photovoltaic devices by embedding Limnospira indica PCC 8005 cyanobacteria in agar and PEDOT:PSS matrices on the surface of boron-doped diamond electrodes. We have subjected them to varying external polarizations while simultaneously measuring current response and photosynthetic performance. For the latter, we employed Pulse-Amplitude-Modulation (PAM) fluorometry as a non-invasive and real-time monitoring tool. Our study demonstrates an improved light utilization efficiency for L. indica PCC 8005 when immobilized in a conductive matrix, particularly so for low-intensity light. Simultaneously, the impact of electrical polarization as an environmental factor influencing the photosynthetic apparatus diminishes as matrix conductivity increases. This results in only a slight decrease in light utilization efficiency for the illuminated sample compared to the dark-adapted state.

DETERMINATION OF ANTI-CANCER DRUG PALBOCICLIB FROM HUMAN BIOLOGICAL FLUIDS BY USING DIFFERENTIAL PULSE VOLTAMMETRIC METHOD AT BORON DOPED DIAMOND ELECTRODE

Objective: A very efficient and sensitive electrochemical technique utilizing differential pulse voltammetry (DPV) at a boron-doped diamond electrode (BDDE) was devised to measure Palbociclib in this study. Material and Method: All experiments employed typical three-electrode cell of 10 ml capacity in conjunction with boron-doped diamond electrode, a platinum wire counter electrode, and an Ag/AgCl reference electrode. During electrochemical measurements, DPV and cyclic voltammetry (CV) methods was utilized at BDDE. Result and Discussion: Based on experimental findings from electrochemical characterization investigations, it was determined that oxidation behavior of Palbociclib in BDDE is irreversible and regulated by diffusion. Anodic peak current exhibited a linear relationship within concentration range of 0.01–1 µM, 0.02–0.8 µM, and 0.02–0.8 µM in pH 2.0 phosphate buffer solution (PBS) for reference substance solution, human serum, and urine samples, respectively. Limits of detection were found as 2.28 nM, 2.93 nM, and 1.31 nM for standard drug solution, human serum and urine samples, respectively. In order to validate the developed method, its repeatability, reproducibility, selectivity, precision and accuracy in all environments were investigated and calculated. This method was successfully applied for the analysis of Palbociclib in human serum and urine samples .

Ni-Pt Core-Shell Formation via Spontaneous Galvanic Displacement Reaction at Boron Doped Diamond Electrodes for Ammonia Oxidation Reaction

Ammonia is a major environmental pollutant that is highly toxic and may cause unfavourable effects to the human body, even in low concentrations. As a result, the monitoring and elimination of NH3 has been an important topic worth exploring in depth. Moreover, ammonia can be a suitable fuel cell source because its theoretical electrical charge density is relatively high and it’s possible to take this advantage by converting ammonia to nitrogen and electrical energy via the ammonia oxidation reaction (AOR). This reaction requires a catalyst to decrease the energy barrier that prevents the molecule from reacting and transforming into nitrogen.Ammonia electro-oxidation reaction has been paid much attention in recent years because it is widely used in various fields. However, the electro-oxidation of ammonia is a complex process, especially the reaction intermediate has a slow toxic effect on the electrode. To reduce the catalyst poisoning by the absorption of intermediate, the constituent and structure of the catalysts must be deeply researched.Herein, a bimetallic Pt–Ni catalyst-modified boron-doped diamond (BDD) electrode was done via spontaneous galvanic displacement reaction for the ammonia oxidation reaction. The synergistic properties may include the promotion of low-temperature oxidation, improvement of the oxidation resistance, and increased catalytic efficiency. BDD was used as the electrode substrate in this work due to its excellent resistance to corrosion and good stability over time in a highly corrosive environment. First, nickel was electro-deposited through chronoamperometry on the BDD electrode surface at a potential of -1.1V vs Ag/AgCl in 0.1M KClO4 & 5mM Ni (NO3)2.6H2O aqueous solution. Second, platinum was deposited on the nickel particles on the BDD electrode surface through a spontaneous galvanic displacement reaction by a redox process which involves the nickel oxidation and Pt2+ reduction, using a K2PtCl4 precursor on the BDD surface while forming a core shell structure. Lastly, the Pt-Ni deposited on the BDD surface was then characterized through different techniques such as XPS, SEM, EDS, and Raman before and after the ammonia oxidation reaction.Preliminary studies of the behaviour of BDD electrodes in the presence of Ni and Pt have been carried out to determine the electrochemical conditions at which the substrate works with these metal salts. The results found with these studies will show how Pt-Ni catalyst will improve AOR in alkaline media.

Near Infrared Aggregation Induced Electrogenerated Chemiluminescence Studies of Xanthene Dye

Electrogenerated chemiluminescence (ECL) serves as a versatile electrochemical-spectroscopic tool for rapid sample analysis, offering high sensitivity, good selectivity, and a low detection limit. During electrochemical redox reactions of luminophores and often ECL co-reactants, excited state luminophore species are formed through high energetic electron transfer between oxidized and reduced luminophore radicals or between the radical cation or anion and co-reactant intermediates. This process emits photons, generating ECL. Near infrared (NIR) luminophores represent an emerging class of materials in ECL studies. However, greater vibronic coupling between the ground and excited state in NIR luminophores with a lower band gap promotes nonradiative decay. The aggregation-induced emission (AIE) phenomenon overcomes these challenges, demonstrating enhanced radiative emission. We conducted a study on the photophysical, electrochemical, and ECL behavior of XanthCR-880 dye, which comprises a thienylpiperidine donor and a xanthene core as an acceptor. The central xanthene core provides extended conjugated length and increased charge transfer, resulting in NIR absorption at 880 nm and fluorescence emission at 960 nm, with a stroke shift of 80 nm. Cyclic voltammetry performed at a Pt electrode in MeCN with a scan rate of 50 mVs-1 revealed two oxidation waves and two reduction waves at 0.35 V, 0.70 V, -0.70 V, and -1.55 V vs Ag/Ag+, respectively. Due to the limited potential window of the Pt electrode in MeCN (not exceeding -2.5 V, a boron-doped diamond (BDD) electrode was employed at more negative potentials, uncovering an additional reduction wave at -2.62 V vs Ag/Ag+. The cathodic and anodic ECL behavior of XanthCR-880 dye was investigated using benzoyl peroxide and 2-(dibutylamino)ethanol as cathodic and anodic co-reactants, respectively. For cathodic ECL, XanthCR-880 dye produced two ECL waves at the BDD electrode, with peak potentials of -2.06 V and -2.36 V, respectively. In anodic ECL, relatively weak emission was observed at 1.05 V. ECL spectra were generated using the cathodic ECL pathway and interference filters as wavelength selectors, revealing a maximum emission at ~975 nm. The proposed ECL mechanism, as well as AIE studies, will also be discussed.

Electro-Oxidation of Cumene Using Diamond Electrodes in Batch and Flow

Selective oxidation of aromatic alkyl side chains is an important molecular transformation process to obtain various materials ranging from rubber and resin to fine chemicals. Generally, molecular oxygen has been utilized in straightforward oxidation of aromatic alkyls. However, since molecular oxygen is highly stable, activation of the molecular oxygen itself is necessary, which requires a specific catalyst and/or harsh condition such as high temperature and high pressure. Recent environmental and sustainable concerns lead to a growing demand for the development of greener oxidation processes.Recently, electro-organic synthesis, referring to an organic synthesis method combined with electrochemistry, has drawn attention as a sustainable synthetic method. Since electro-organic synthesis utilizes electricity itself as a reagent, reactions proceed well even under ambient conditions and reagent wastes are reduced to a minimum. In electro-organic synthesis, electrode materials are one of the most significant parameters because reactions occur at the anode and/or cathode. Boron-doped diamond (BDD) is a relatively new electrode material and shows a wide potential window, which can be applied to the transformation of compounds with high redox potentials. Therefore, BDD electrodes would enable a straightforward oxidation reaction of aromatic alkyls, which is difficult to achieve with other conventional electrode materials.Herein, we report the straightforward electro-oxidation of cumene, one of the most important and extensively investigated aromatic alkyls, by BDD electrodes. The role of electrode materials was investigated with electrochemical measurements. Furthermore, the cell design (i.e. batch vs. flow) was examined, and we realized that the product selectivity of cumene oxidation can be switched by simply changing the cell design.First, we carried out the electrolysis of cumene under the constant current condition in an undivided batch cell. The main product was acetophenone under the following optimum conditions: (solvent) MeCN, (supporting electrolyte) Et4NClO4, (current density) 2.1 mA/cm2, (amount of charge) 5 F referring to mole of cumene. It should be noted that almost no acetophenone was obtained when the combination of anode and cathode was graphite/graphite or Ni/Ni. Cyclic voltammetry using BDD as a working electrode showed a clear oxidation peak of cumene at around 2.40 V (vs. Ag/Ag+). On the other hand, no clear oxidation peak was observed when using graphite or Ni as a working electrode. This is because potential windows of graphite and Ni are too narrow to oxidize cumene directly. Overall, the electrochemical measurements indicate the BDD’s wide potential window enables direct oxidation of cumene to produce a key reaction intermediate to afford acetophenone. A series of electrolysis experiments confirmed that the reaction intermediate is the cumyl cation and the oxygen source is the superoxide generated by reduction of dissolved oxygen on the cathode. A proposed mechanism is as follows. Anodic oxidation of cumene on the BDD electrode affords a cumyl cation. On the other hand, cathodic reduction of dissolved oxygen produces the superoxide and even the hydroperoxide anion. Addition of the hydroperoxide anion to the cumyl cation yields cumene hydroperoxide, which is further converted into acetophenone.Second, we carried out the electrolysis of cumene under the constant current condition in an undivided flow cell. The main product was a-cumyl alcohol under the following optimum conditions: (solvent) MeCN, (supporting electrolyte) Et4NClO4, (current density) 0.25 mA/cm2, (amount of charge) 1 F referring to mole of cumene, (flow rate) 0.375 mL/min. A series of flow electrolysis experiments indicated that cumene is converted into a-cumyl alcohol via cumene hydroperoxide, and then to acetophenone, which is supported by cyclic voltammetry measurements: the potential at which the current value increases was lower in the order of cumene hydroperoxide > a-cumyl alcohol > cumene > acetophenone. A proposed mechanism is as follows. A hydroperoxide anion generated at the cathode added to a cumyl cation generated at the anode to form cumene hydroperoxide. The O-O bond in cumene hydroperoxidewas cleaved anodically to form alkoxy radical, which underwent a hydrogen atom transfer (HAT) between cumene to yield a-cumyl alcohol and cumyl radical. Furthermore, a-cumyl alcoholwas oxidized into the alkoxy radical, followed by b-scission to yield acetophenone. Therefore, it is suggested that the selective conversion of cumene into a-cumyl alcohol in flow electrolysis was due to suppressing overoxidation of a-cumyl alcoholinto acetophenone. Figure 1