Boron-doped Diamond Electrode Research Articles

The Electrooxidation of Synthetic Bipyridyl Herbicide Wastewaters with Boron-Doped Diamond Electrodes: A Technical and Economic Study to Boost Their Application for Pollution Prevention in the Agricultural Sector

Boron-doped diamond electrodes (BDDEs) offer a highly efficient pathway to mineralize recalcitrant compounds due to their reduced energy requirements, fewer chemical inputs, and mechanical stability. In this work, the electrochemical degradation of paraquat (PQ) and diquat (DQ) was studied using an undivided cell (Condiacell®-type) at circumneutral pH, and under galvanostatic control. The roles of applied current density, volumetric flow rate, and herbicide concentration were systematically studied through a central composite design (CCD) using a closed-flow reaction setup. Under the best operating conditions (i.e., for PQ: 1.6 mA/cm2, 80 mL/min, and 70 mL/min, and 70 mg/L; and for DQ: 1.5 mA/cm2, 80 mL/min, and 73 mg/L), a spectrophotometric analysis evidenced that the herbicides were satisfactorily removed (ca. 100%) while mineralization degrees were above 90%. Furthermore, the produced effluents yielded significant increases in seed germination and root length, which suggest a reduction in toxicity. Energy consumptions of 0.13 and 0.18 kWh/g of TOC are reported with the electrochemical cells for the PQ and DQ treatments, respectively. The PQ and DQ treatments by electrooxidation are estimated to emit nearly 2.7 and 38.9 kg CO2/m3 of water treated, with a cost around USD 250/m3. Carbon emissions could be greatly decreased for PQ (0.28 kg CO2/m3) and DQ (0.40 kg CO2/m3) if electricity were generated from renewable resources. Although this study suggests that the use of BDDE can be considered as a green alternative for agrochemical removal due to lower carbon emissions, the environmental profile of the process is determined by the degree of renewability of the electrical grid of each country or region.

Electroanalysis of Statin Drugs: A Review on the Electrochemical Sensor Architectures Ranging from Classical to Modern Systems.

An overview of the latest advances in the design of electrochemical sensor architectures dedicated to the determination of drugs from the statin class is presented in this review. Statins are drugs widely consumed for cholesterol control, and their determination in different matrices through the application of electroanalysis is growing considering advantages such as operational simplicity, lower cost and ease of sample preparation. Within the context of statins, electrochemical sensor architectures can be subdivided into conventional/classical electrodes such as glassy carbon electrodes, carbon paste electrodes, pencil graphite electrodes, boron-doped diamond electrodes and metallic electrodes, and more modern electrode systems, including the screen-printed electrodes and 3D-printed electrodes. Thus, different aspects related to the preparation of these electrochemical sensors and analytical performance are presented, also reflecting advances in terms of designs of new architectures and possible improvements not previously reviewed. Analyzed samples, advantages and disadvantages of different implemented sensor's modification strategies and perspectives for the electroanalysis of statins are also included throughout the work.

Electrochemical carboxylation: Green synthesis of atrolactic acid using boron-doped diamond electrodes

Electrochemical CO2 fixation is vital for sustainability in the chemical industry, yet the selective synthesis of multi-carbon products remains challenging. Organic electrosynthesis offers promise by enabling precise control over reaction conditions and facilitating novel reactivity patterns. One such technique, electrochemical carboxylation, involves coupling CO2 with organic molecules to produce carboxylic acids. Specifically, electro-carboxylation of acetophenone yields atrolactic acid, a valuable precursor for nonsteroidal anti-inflammatory drugs, providing a greener alternative to traditional production methods. This study focuses on the synthesis and characterization of boron-doped diamond (BDD) films using the microwave plasma-assisted chemical vapor deposition (MP-CVD) method and synthesized BDD electrodes were then used for the electrolytic carboxylation of acetophenone. Various analytical techniques, including X-ray diffraction (XRD), Raman spectroscopy, and laser microscopy, etc. were employed to characterize the BDD films. Various BDD films synthesized for different durations were utilized in the electrolytic carboxylation of acetophenone, with the highest yield of atrolactic acid (25 %) achieved using a BDD film synthesized over 6 h. Also, the effect of BDD surface modification i.e. oxygen and hydrogen terminated BDD on the synthesis of atrolactic acid was studied. Additionally, different electrolytes were employed in the synthesis process of atrolactic acid. A comparative study between Pt and BDD electrodes for the electrolytic carboxylation of acetophenone was conducted, and a mechanism for the formation of atrolactic acid was proposed.

Electrochemical determination of nitazoxanide in environmental and pharmaceutical samples using a boron-doped diamond electrode

Consumption of Nitazoxanide (NTZ), a compound belonging to the class of nitrothiazoles, has increased due to its efficiency in treating viral gastroenteritis caused by rotavirus and norovirus “coronavirus disease”. Thus, developing a method capable of monitoring NTZ in wastewater and pharmaceutical formulations is relevant to human health control. However, most methods for NTZ determination are expensive and time-consuming. Hence, we present a fast, efficient, and low-waste method for NTZ monitoring in drugs and water samples using a boron-doped diamond electrode. A 3D-printed electrochemical cell with a capacity of 2 mL was used for all studies. Besides the simplicity of low waste generation, the method provided good analytical performance with a linear range of 2.0–20.0 µmol/L of NTZ, and a limit of detection (LOD) of 0.57 µmol/L. Recovery percentages between 99 and 107 % were obtained to analyze spiked samples. In addition, we demonstrate that the LOD value can be significantly improved by 50 times after applying a pre-concentration step using solid-phase extraction. Therefore, we believe the described approach is a simple and efficient electrochemical method for monitoring NTZ levels in pharmaceutical and environmental samples without laborious sample preparation procedures. This is the first report to describe the use of BDD electrodes for NTZ monitoring and environmental sample analysis using an eco-friendly approach.

Surface Fluorination Mediated Electro-Oxidative Degradation of HFPO-DA on Boron-Doped Diamond Electrode

Heptafluoropropylene oxide dimer acid (HFPO-DA), as an alternative to perfluorooctanoic acid (PFOA), has been shown to pose similar environmental and health risks as other perfluorinated compounds. The electrochemical-based advanced oxidation processes are promising techniques for the treatment of perfluorinated compounds, and the boron-doped diamond (BDD) anode could degrade HFPO-DA under mild conditions. However, the roles of radicals in the degradation and how to overcome the steric hindrance of the –CF3 branch on the carboxyl group were not yet clear. In this study, we investigated the degradation mechanism of HFPO-DA on the BDD anode. Instead of other non-active anodes (PbO2 and SnO2 electrodes), HFPO-DA can be degradable on the BDD electrode with a rate constant logarithmic correlation to the applied current density. The hydroxyl radical (•OH) was one of the key factors in the degradation of HFPO-DA, accounting for almost 89% of the significant effect, and the direct electron transfer was the rate-limiting step in the degradation reaction. Physicochemical characterization including field emission scanning electron microscope (FE-SEM), X-ray photo-electron spectroscopy (XPS), water contact angle, and electrochemical property indicated that the BDD electrode was fluorinated after electrolysis, the electrode surface became more hydrophobic due to the bonding of –CxFy, leading to a decrease in the electrochemically active area. Moreover, degradation products (pentafluoropropionic acid, trifluoroacetic acid, and fluorine ion) were detected and the mass balance of carbon and fluorine was calculated during the degradation. Therefore, a degradation mechanism for HFPO-DA was proposed, which involved direct electron transfer, decarboxylation, radical reaction, decarboxylation, and decarboxylation. The de–CF3 step initiated the fluorination of the BDD electrode, which was initiated by the defluorination process. This study contributes to the understanding of the electro-oxidative degradation of perfluoroalkyl ether carboxylic acids and provides guidance for the application of electrochemical advanced oxidation processes.

Advanced Bionic Technology Combining Online Electrochemistry-Mass Spectrometry and Offline Electrochemistry-Liquid Chromatography-Mass Spectrometry for Simulating and Characterizing Metabolic Processes of Bioactive phenolic acids in Natural Products.

The metabolism research of bioactive phenolic acids widely found in natural products is of great significance for elucidating pharmacologic mechanisms and screening lead compounds. However, it is time-consuming and vulnerable to interference to conduct the traditional metabolism approach by applying organisms or biomaterials. Herein, a bionic technology was established by combining online electrochemistry-mass spectrometry (EC-MS) with offline electrochemistry-liquid chromatography-mass spectrometry (EC-LC-MS) to investigate the oxidative transformation and metabolic processes of the active phenolic acids (including salvianolic acid A, caffeic acid, 3, 5-O-dicaffeoylquinic acid, ferulic acid, salvianic acid A, and protocatechuic acid). Phase I metabolism of the phenolic acids were simulated by applying a three-electrode controlled potential electrochemical reactor with a boron-doped diamond electrode, with glutathione mixed into the oxidative products simultaneously for obtaining the phase II metabolites. Finally, structural characterization of the simulated metabolites of the phenolic acids was achieved successfully, including hydroxylation, methylation, demethylation, decarboxylation, etc. It was revealed that the simulated metabolism process based on an electrochemical system was effective in yielding a wide variety of metabolites for these compounds, which was also compared with the metabolism results applying rat liver microsomes. Consequently, this bionic technology is expected to be a powerful tool to investigate the material basis for the efficacy of active ingredients of natural products.

Study on the electrochemical oxidation mechanism of sulfamethoxazole using three-dimensional boron-doped diamond

In this study, we prepared a novel three-dimensional boron-doped diamond (BDD) electrode. Subsequently, we systematically conducted an electrochemical oxidation reaction on sulfamethoxazole (SMX) using a BDD anode and a platinum plate (Pt) cathode. The effects of initial concentration, current density, initial pH, and carrier electrolyte on SMX degradation were investigated. The SMX was completely removed after 4 h of electrolysis at a current density of 30 mA/cm2, 0.1 mol sodium sulphate as the supporting electrolyte, and a pH of 7. Additionally, the COD removal rate was 65.6 %, while the energy consumption was 40.1 %. Compared with two-dimensional BDD electrode degradation, the energy saving was 54 %. Density functional theory (DFT) and high-performance liquid chromatography (HPLC) were used to analyse the SMX degradation mechanism. Three possible degradation pathways were proposed: ·OH substitution of the amino group in the aromatic ring, oxidation of the amino group to nitrogen dioxide, and addition of ·OH to the isoxazole ring. The active sites detected in the reaction corresponded closely with the calculated results using DFT. Moreover, ECOSAR toxicity analysis was applied to evaluate the toxicity of the intermediates produced during electrolysis. We discovered that the toxicity of SMX and its intermediates decreased significantly during electrolysis.

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.

Electrochemical advanced oxidation of biotreated dyeing and finishing wastewater by boron doped diamond electrode

The combination of advanced oxidation processes (AOPs) and biological treatments is a promising technique for the treatment of textile wastewater. In this study, a boron-doped diamond (BDD) electrode was utilized for electrocatalytic oxidation to abate organic pollutants in biotreated dyeing and finishing wastewater (BDFW). Three operational parameters of BDD electrochemical oxidation of BDFW were evaluated. The results showed that increasing the applied current density, decreasing the planar electrode spacing, and lowering the pH value all enhanced the COD removal efficiency. After 300min, the COD removal efficiency exceeded 90% and the specific energy consumption (Esp) was 129 kWh/kg COD. BDD electrochemical oxidation removed most of macromolecular organic compounds from the wastewater. Based on the excellent performance of five consecutive runs, the BDD electrochemical oxidation proves to be a promising technique as an advanced treatment of biologically pretreated wastewaters in practical applications.

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.