Boron-doped Diamond Electrode Research Articles

Sensing ivacaftor accomplished using the square-wave voltammetric technique with the assistance of a cationic surfactant on a boron-doped diamond electrode

This investigation aims to describe the voltammetric analysis of ivacaftor (IVA) by utilizing the boron-doped diamond (BDD) electrode to add a cationic surfactant. Cyclic voltammetry via Britton-Robinson (BR, 0.04 mol L−1, pH 2.0) buffer was used to perform determinations of the IVA demonstrating irreversible behaviors, adsorption-controlled and well-defined (+1.04 V, PA1) and an ill-defined (+1.42 V, PA2) oxidation peaks (vs. Ag/AgCl). The findings revealed that the oxidation peaks of IVA are pH-dependent (ranging from 2.0 to 5.0). The use of cetyltrimethylammonium bromide (CTAB, cationic surfactant) in the chosen supporting electrolyte enormously raised the oxidation peak currents of IVA. For the measurement of IVA in a 0.04 mol L−1 BR buffer solution with a pH of 2.0, the linear relationship was discovered to exist under the conditions of the experimental optimal parameters involving 2 × 10−4 mol L−1 CTAB at +1.11 V (vs. Ag/AgCl) (after an accumulation of 60 s at the open-circuit condition). The linear concentration was discovered using 0.25 to 10.0 μg mL−1 (6.4 × 10−7-2.5 × 10−5 mol L−1) and the limit of detection 0.073 μg mL−1 (1.9 × 10−7 mol L−1). The devised methodology was effectively employed to determine IVA in pharmaceutical formulation. To the best of our understanding, it represents the first electroanalytical method for detecting IVA by voltammetry.

Voltammetric behavior of solifenacin succinate on gold, glassy carbon and boron-doped diamond electrodes: Stability testing and determination

The anticholinergic drug, solifenacin, is frequently used for the treatment of the urological tract for urinary incontinence, and urinary frequency. The development of reliable and effective solifenacin electrochemical sensors is of great importance for the pharmaceutical industry and clinical practice. In this work, the electrochemical behavior of solifenacin succinate (SOL) was studied using three different working electrodes: gold (Au), glassy carbon (GCE) and boron-doped diamond electrode (BDDE). The cyclic voltammetric (CV) measurements performed in 0.05 M NaHCO3 indicated that the SOL oxidation process is irreversible and diffusion-controlled at all investigated working electrodes. Afterwards, the testing of SOL electrochemical stability and the possibility of its electrochemical degradation was performed at the Au electrode by the cycling of the potential during 3 h and continuously to 6 h. It was shown that the SOL was electrochemically transformed into another electroactive species and its degradation was excluded. For electroanalytical application, the anodically pretreated BDDE (+2.0 V; 30 s) was selected. Various experimental parameters were optimized, including the pH of the aqueous Britton-Robinson (B-R) buffer as a supporting electrolyte (from pH 2.0 to 11.98) and the most intensive peak of the target analyte was at pH 11.0, so this pH value was chosen as the optimum for further measurements. Based on the correlation of the SOL peak intensity and different concentrations, the developed differential pulse voltammetric (DPV) method was characterized by a linear concentration range from 0.041 to 2.50 µM, with a correlation coefficient of 0.999, and a relative standard deviation of 0.3 %. Taking into account the sensitivity of the developed DPV method towards the electrochemical oxidation of SOL, a very low detection limit of 0.012 µM in the model system was achieved. The BDDE showed adequate selectivity for SOL in the presence of the investigated interferents. The obtained results indicate that the BDDE with an optimized DPV method could be applied for the trace-level electroanalytical determination of SOL in human urine sample with excellent recovery and reproducibility.

Design-Dependent Electrophysiological Effects of Electrolysis Electrodes Used for Endodontic Disinfection

Electrochemical disinfection in dentistry using boron-doped diamond (BDD) electrodes bears the potential risk of disturbing vital functions. Applying different arrays of BDD electrodes and an electrotome as reference, it was the goal of this animal study to compare their effects on an electrocorticogram (ECoG) and electrocardiogram (ECG). Following the trepanation of teeth in rats, the electrodes and electrotome were applied in a randomized manner while recording ECoG and ECG. The recordings were classified according to an electrophysiological significance score based on involvement, extent of disruption and duration. The scores obtained were compared by means of ANOVA followed by Dunn’s multiple comparisons test (α = 0.05). Voltage type and electrode design had a significant influence on the detectable electrophysiological effects. The results seen with BDD electrodes ranged from no detectable electrophysiological effects to a pronounced effect. The application of the electrotome induced the most pronounced effects. Given that electrotomes are safe medical devices, despite evoking greater disturbance compared to BDD electrodes, regardless of their design, electrochemical disinfection may be considered a safe procedure.

Parallel paired electrolysis of green oxidizing agents by the combination of a gas diffusion cathode and boron-doped diamond anode

The generation of “green” oxidizing agents by electrochemical synthesis opens the field for sustainable, on-demand, and on-site production, which is often based on non-critical starting materials. In this study, electrosyntheses were carried out on different cathode and anode materials. In half-cell experiments, the cathodic synthesis of peracetic acid (PAA) was investigated on gas diffusion electrodes (GDEs), reaching 22.6 mmol L−1 of PAA with a current efficiency (CE) of 7.4%. Moreover, peroxodicarbonate (PODIC®) was produced anodically on boron-doped diamond (BDD) electrodes with concentrations as high as 42.7 mmol L−1 PODIC® and a CE of 30.3%. Both cathodic and anodic processes were individually examined and improved. Finally, the half-cell reactions were combined as a proof of concept in a parallel paired electrolysis cell for the first time to achieve an increased overall CE.

High pressure and high temperature synthesized boron-doped diamond electrodes for effective waste water treatment

The development of efficient and sustainable wastewater treatment technologies is vital to resolve environmental concerns. Finding an effective catalyst for the degradation of organic pollutants in wastewater is challenging. In this study, boron-doped diamond (BDD) particles were synthesized using a high-pressure high-temperature (HPHT) industrial diamond synthesis technology. BDD was investigated as an efficient electrode catalyst to convert organic pollutants into biodegradable substances. BDD self-supporting electrodes exhibited excellent properties with a relative density of 93.07%, an electrical resistivity of 2.71 × 10−4 Ω·m. Furthermore, BDD particles showed superior electrochemical characteristics such as a rapid electron transfer coefficient of about 0.5, good reversibility and redox properties. The BDD self-supporting electrode achieved a methylene blue degradation rate of 98.72% within 60 min. Our research provides valuable insights into using BDD as an effective electrochemical catalyst for wastewater treatment, which can help promote the development of environmentally friendly and economically viable technologies.

Electrochemical and theoretical studies of the interaction between anticancer drug ponatinib and dsDNA

In this study, electrochemical and theoretical studies were performed to explain the interaction mechanism between ponatinib (PNT), a third generation tyrosine kinase inhibitor, and dsDNA. The electrochemical part was conducted in phosphate-buffered saline (PBS) at physiological pH of 7.4 and in acetate buffer with a pH of 4.7, using square wave voltammetry. A boron-doped diamond electrode was used in a bulk-incubated solution. The theoretical part was investigated using computational methods, such as the semiempirical method PM7 and density functional theory (DFT). Significant differences in the electrochemical behavior of PNT in the presence of DNA confirmed the occurrence of interactions. The results obtained in the acetate buffer strongly suggested the preferential interaction of PNT with guanine residues. However, at physiological pH, it can be concluded that PNT interacts with dGua and dAdo in the dsDNA molecule. These results are consistent with outcomes from the theoretical studies, where quantum-chemical calculations showed that both electrochemically detectable nucleobases form hydrogen bonds with the drug. These bonds appeared to be stronger with guanine than with adenine. According to the computational studies, the dsDNA major groove is the energetically preferred site for the complexation of PNT.

Low-interference and sensitive electrochemical detection of glucose and lactate using boron-doped diamond electrode and electron mediator menadione.

To minimize background interference in electrochemical enzymatic biosensors employing electron mediators, it is essential for the electrochemical oxidation of electroactive interfering species (ISs), such as ascorbic acid (AA), to proceed slowly, and for the redox reactions between electron mediators and ISs to occur at a low rate. In this study, we introduce a novel combination of a working electrode and an electron mediator that effectively mitigates interference effects. Compared to commonly used electrodes such as Au, glassy carbon, and indium tin oxide (ITO), boron-doped diamond (BDD) electrodes demonstrate significantly lower anodic current (i.e., lower background levels) in the presence of AA. Additionally, menadione (MD) exhibits notably slower reactivity with AA compared to other electron mediators such as Ru(NH3)63+, 4-amino-1-naphthol, and 1,4-naphthoquinone, primarily due to the lower formal potential of MD compared to AA. This synergistic combination of BDD electrode and MD is effectively applied in three biosensors: (i) glucose detection using electrochemical-enzymatic (EN) redox cycling, (ii) glucose detection using electrochemical-enzymatic-enzymatic (ENN) redox cycling, and (iii) lactate detection using ENN redox cycling. Our developed approach significantly outperforms the combination of ITO electrode and MD in minimizing IS interference. Glucose in artificial serum can be detected with detection limits of ~ 20μM and ~ 3μM in EN and ENN redox cycling, respectively. Furthermore, lactate in human serum can be detected with a detection limit of ~ 30μM. This study demonstrates sensitive glucose and lactate detection with minimal interference, eliminating the need for (bio)chemical agents to remove interfering species.

Development of environmentally friendly voltammetric methods for the individual and simultaneous determination of antihypertensives: Validation and application

In this study, voltammetric methods were developed and validated for the individual determination of lisinopril (LSNP) and its association with hydrochlorothiazide (HCTZ) employing a cathodically pretreated boron-doped diamond (CP-BDD) electrode. The studies of the experimental and instrumental parameters that affect the performance of both methods were carefully carried out by optimizing each parameter. The methods were validated by evaluating the figures of merits recommended by the validation guidelines. The method for the individual determination of LSNP presented a linear working range between 9.99 and 196.01 nmol L−1, with a limit of detection of 3.05 nmol L−1 by differential pulse voltammetry in BR buffer solution (pH 2.0). Simultaneous analytical curves over the concentration ranges of 0.40–3.99 and 0.050–1.045 μmol L−1 for HCTZ and LSNP, respectively, were obtained by square-wave voltammetry in Britton-Robinson buffer solution (pH 3.0). The limit of detection values calculated were 0.052 μmol L−1 and 0.020 μmol L−1, respectively for HCTZ and LSNP. The sensitivity observed for individual analytical curves of HCTZ and LSNP was statistically equal to that obtained for the simultaneous analytical curves at the 95 % confidence level. The developed methods were applied to determine these drugs in environmental, biological, and pharmaceutical samples, with satisfactory results. The method's greenness was assessed demonstrating that both validated methods constitute a greener alternative to conventional analytical methods reported in the literature.

Electrochemical reduction of CO2 using boron-doped diamond electrodes: the influence of deposition times

To promote the electrocatalytic transformation from CO2 to value-added chemicals with boron doped diamond (BDD) electrode, it is critical to make clear that the relationship between the B doping state and the position of B atom in BDD materials and CO2 reduction performance. Here, a series of BDD electrodes with constant B dopant amount on the surface were prepared by the same process but based on different deposition time (3, 6, 12, and 24 h) using the heat filament chemical vapor deposition. The results demonstrated that the surface grain size, abundances of B–C relative to B–B bonds of the BDD films increased with increasing the deposition time. Moreover, the formic acid yield and faradaic efficiency also increased as well during electrochemical CO2 reduction due to more available B atoms doped in crystallinity (B–C bonds) rather than in grain boundary (B–B bonds) of BDD. Finally, electrochemical analysis revealed that the B–C bonds in the crystal of BDD films is the active sites for the reduction of CO2. This study provides a simple and convenient path to figure out what is the active site of the BDDs and its how to impact the CO2 reduction.

Development of an Electroanalytical Method for Ronidazole Determination in Environmental and Food Matrices Using Boron-Doped Diamond Electrode

A novel electroanalytical approach is presented for the determination of ronidazole in environmental and food matrices by applying a cathodically pretreated boron-doped diamond electrode and the square-wave adsorptive cathodic stripping voltammetry technique. From the studies of cyclic voltammetry to investigate the electroactivity of the ronidazole molecule, the occurrence of an irreversible cathodic process was verified, which was more efficiently detected using the cathodically pretreated boron-doped diamond electrode compared to the anodically pretreated electrode. Still on the electrochemical response of ronidazole, the effects of pH and scan rate were studied and, its apparent diffusion coefficient was determined by chronoamperometry (8.20 × 10−6 cm2 s−1). Under optimal experimental conditions, the analytical curve obtained for ronidazole was linear in two concentration ranges (12.70 to 63.40 µmol L−1 and 76.04 to 126.2 µmol L−1), with a limit of detection of 2.55 µmol L−1. For intra- and inter-day repeatabilities, relative standard deviations of only 2.7 and 3.5% were verified, which demonstrated the stable analytical response of the electrode. Recovery percentages ranging from 96 to 100% were achieved in the analysis of natural water and whole milk samples. Therefore, the proposed electroanalytical method shows satisfactory analytical performance towards ronidazole determination in varied matrice samples.

Electrochemical oxidation of Rhodamine B in dye wastewater by a novel boron-doped diamond electrode: parameter optimization and degradation mechanism

The escalating pollution of water resources, predominantly attributable to the printing and dyeing industry, has garnered increased attention towards the treatment technology for such wastewater. In this study, an innovative boron-doped diamond electrode was employed for the removal of Rhodamine B (RhB) in dye wastewater through electrochemical oxidation (EO). The optimization of process parameters was achieved through a single-factor experiment. The degradation pathway of RhB was examined using Density functional theory calculations and Liquid chromatography-mass spectrometry. The results showed that when pH = 7, j = 40 mA∙cm−2, c(Na2SO4) = 0.035 mol·dm−3, and c0(RhB) = 50 mg·dm−3, the removal efficiency could reach 93.83% at 60 min. The EO process of RhB adhered to pseudo-first-order kinetics. The degradation process of RhB primarily encompasses several stages: deethylation reaction, destruction of the conjugated structure, decolorization, degradation reaction, and ring-opening mineralization reaction. This study offers a theoretical foundation for the practical implementation of BDD electrode electrochemical oxidation technology in dye wastewater treatment.

Fast and simple voltammetric sensing of avanafil in the pharmaceutical formulation by using unmodified boron-doped diamond electrode.

Erectile dysfunction is a common issue among adult males involving difficulty in maintaining an erection, and it is often treated with fast-acting, low-side-effect drugs like avanafil (AVN), among other phosphodiesterase-5 inhibitors. Hence, developing fast, simple, and sensitive methods to detect AVN is crucial. This study conducts an electroanalytical inquiry and provides a new voltammetric method for accurately analyzing AVN utilizing a boron-doped diamond (BDD) electrode without any modifications. In the Britton-Robinson buffer (BR, 0.04 mol L-1, pH 4.0), cyclic voltammetry showed a clearly defined and irreversible anodic peak at around +1.44 V relative to Ag/AgCl. The pH of the solution was shown to have an impact on the voltammetric signals of the oxidation peaks. A good linear response for AVN quantification was achieved using square-wave voltammetry. This was done in a 0.04 mol L-1 BR (pH 4.0) solution at a potential of +1.33 V (vs. Ag/AgCl). The method exhibited a wide dynamic range of 0.5 to 30.0 μg mL-1 (1.0 to 62 μmol L-1) and a low limit of detection of 0.14 μg mL-1 (0.29 μmol L-1). The method proposed demonstrated suitability for determining AVN content in pharmaceutical formulations. The accuracy of the approach was demonstrated by comparing the results obtained using the developed method with those achieved using the UV-Vis spectrometry method. Our method simplifies the analytical process by eliminating the need for electrode modification, reducing both time and resource requirements while enhancing overall feasibility.

Підготовка проб сечі для вольтамперометричного визначення лікарських речовин та оцінювання методики з погляду еколологічності

This work discusses the primary methods of preparing urine samples for voltammetric analysis. To serve as model analytes, well-known and commonly used medicinal substances were employed. These substances exhibit distinct pharmacological effects and undergo varying transformations at the electrodes under voltammetry conditions. The selected model analytes encompass two alkaloids of plant origin – quinine and platyphylline, the platyphylline metabolite – its N-oxide, and the synthetic antibacterial drug sulfadimethoxine. The determination of model analytes in prepared samples of urine was carried out using a boron-doped diamond electrode and a dropping mercury electrode. The action of ultrasound on the urine sample turned out to be the optimal method of sample preparation, which allows you to liquid or other types of extraction and significant dilution of sample urine. Furthermore, the environmental aspects of voltammetric analysis for medicinal substance determination in urine, exemplified by quinine, were assessed. Various approaches, such as AGREEprep, AGREE metrics, Green Certificate, and Blue Applicability Grade Index (BAGI), were employed to evaluate environmental considerations. All these assessments yielded high ratings, indicating compliance with the principles of green analytical chemistry for the voltammetric technique in quinine determination in urine.

Cloud point method applied to the extraction and preconcentration of thiabendazole pesticide from whole grape juice samples and amperometric detection by HPLC.

A cloud point method was developed and applied for the first time to extract and preconcentrate thiabendazole (TBZ) from commercial whole grape juice samples, with determination by high performance liquid chromatography coupled to electrochemical detection (HPLC/EC), using a cathodically pretreated boron-doped diamond electrode (BDD). The best conditions for extraction and preconcentration of TBZ by cloud point extraction (CPE) were performed at pH 6.0, by adding 1 mL of the surfactant Tergitol TMN-6 at 10% (mass-to-mass ratio), without heating (at 27 °C) and ultrasonic stirring time of (20 kHz) for 60 min. The HPLC/EC determination was duly validated in a C8 column, in mobile phase with a 69 : 31 ratio (V/V) of phosphate buffer (pH 7.0):ACN, at a flow rate of 1.2 mL min-1 and electrochemical detection with BDD electrode by applying 1.40 V × Ag/AgCl (3.0 mol L-1). Under these conditions, the procedure showed a preconcentration factor (FC) of 21.7, and limits of detection (LOD) and quantification (LOQ) of 6.64 × 10-9 mol L-1 (or 1.33 μg L-1) and 1.66 × 10-8 mol L-1 (or 3.34 μg L-1), respectively. The method provided a percent recovery of 81% to 98%, with a coefficient of variation between 3% and 15%.

Electrocatalytic water treatment of per- and polyfluoroalkyl substances reduces adsorbable organofluorine and bioaccumulation potential.

Per- and polyfluoroalkyl substances (PFAS) are pervasive in industrial processes, eliciting public concern upon their release into municipal sewers or the environment. Removing PFAS from the environment has become an urgent need. However, because potential endpoints span from energy-intensive complete mineralization to partial PFAS transformation, understanding and developing metrics for evaluating PFAS treatment can be a challenge. The goal of this study was to evaluate and compare the effectiveness of electrocatalytic degradation of PFAS with boron-doped diamond (BDD) electrodes using four techniques: LC-MS/MS target analysis, fluoride ion (F-), adsorbable organofluorine (AOF), and bioaccumulation potential using lipid-bilayer partition (LBP) tests. After 3 hours of electrocatalysis, >99% perfluorooctanoic acid (PFOA) degradation was achieved and corresponded with 84% conversion to F-, which was substantial - though intentionally not complete - defluorination. For the same 3 hour treatment time, AOF and LBP coefficient were reduced by 95% and 83%, respectively. LBP's detection limit was 2 orders of magnitude higher than that of AOF, so the positive correlation observed between LBP and AOF (r = 0.86) suggests AOF's practical utility as a design metric for assessing bioaccumulation potential of various organofluorine transformation by-products.

Simultaneous estimation of total phenolic and alkaloid contents in the tea samples by utilizing the catechin and caffeine oxidation signals through the square-wave voltammetry technique

This work outlines the simultaneous estimation of the total phenolic and alkaloid contents in the tea samples by using catechin (C) and caffeine (CAF) oxidation signals at a non-modified boron-doped diamond (BDD) electrode. Two irreversible oxidation peaks, about + 1.03 (for C) and + 1.45 V (for CAF) vs Ag/AgCl in acetate buffer solution at pH 4.7, were seen in the cyclic voltammetric profile of the binary mixtures of C and CAF. In optimal conditions and utilizing the square-wave mode, the BDD electrode allows for simultaneous quantification of C and CAF within the concentration ranges of 5.0–100.0 µg mL−1 (1.72 × 10-5 − 3.45 × 10-3 mol/L) and 1.0–50.0 µg mL−1 (5.15 × 10-6 − 2.57 × 10-4 mol/L) respectively. The corresponding detection limits are 1.22 µg mL−1 (4.21 × 10-6 mol/L) for C and 0.11 µg mL−1 (5.66 × 10-7 mol/L) for CAF. Other phenolic compounds (like tannic acid, gallic acid, epicatechin, and epigallocatechin gallate) and other alkaloids (theophylline and theobromine) present in tea samples were examined for selectivity assessment. Ultimately, the applicability of the proposed approach was demonstrated by estimating the total phenolic and alkaloid contents in the black and green tea samples, expressed as C and CAF equivalents. The results obtained were contrasted against those acquired using UV–Vis spectrometry.

Gas-Phase Electrochemical Conversion of Methane on Boron-Doped Diamond Gas Diffusion Anodes

Methane as the primary component of natural gas is used as fuel for energy supply and serves as a major feedstock for the chemical industry to produce hydrogen. In addition, renewable methane is becoming available via thermochemical, photo- or electrochemical, and biogenic routes. It remains a challenge, however, to efficiently activate the C-H bond of methane while keeping the reaction kinetics under control to form value added products (hydrocarbons or alcohols) and avoid complete oxidation to CO2 [1]. A promising way to selectively activate the C-H bond of methane is to utilize reactive oxygen species (ROS) [2]. ROS play a major role in the partial electrochemical oxidation of water to produce hydrogen peroxide with boron-doped diamond (BDD) anodes [3]. However, little is known about the role of ROS towards CH4 activation under electrochemical conditions. The goal of our work is to achieve control over product selectivity in the gas-phase electrochemical conversion of methane towards methanol or C2+ products [4, 5]. We also aim to explore the role of water in the methane conversion mechanism using in-situ electrochemical FT-IR spectroscopy.Experimentally, we use a BDD coated mesh as gas-diffusion anode electrode in a zero-gap gas-phase electrolyzer. The anode side of the cell is fed with humidified or dry CH4 (or He for control experiments) and humidified He or H2O are fed to the cathode side (to keep the Nafion 117 membrane humidified). The electro-oxidation of water is paired with hydrogen evolution.. The scheme of the membrane electrode assembly is shown on Fig. 1. A.In this talk, we discuss the effects of water content, gas flow rate and methane pressure on product selectivity. We observe the formation of CO2 and CO along with O2 when humidified CH4 is fed to the anode side of the electrolyzer (and H2O is fed to the cathode). CO2 and CO originate from the oxidation of CH4, as confirmed by control experiment with only He fed to the anode (Fig. 1. B). This suggests that ROS, generated at the BDD electrode by water partial oxidation, can oxidize methane. However, O2 is still the major product even in the presence of CH4 and both conversion and selectivity are low. The missing Faradaic efficiency (Fig. 1. C) can be related to non-detected CH4 oxidation products – for this, we are currently deploying additional analytical techniques besides gas-chromatography, e.g., IR, NMR, and HPLC, to detect minor products in both gas and liquid phases.When running experiments with humidified CH4 gas feed on the anode and humidified He gas feed on the cathode, we observe that the CO to CO2 ratio increases. This indicates that the selectivity changes significantly while the cell (and the membrane) dries out. Hence, we propose that the product selectivity can be controlled by tuning the humidity level.Finally, in experiments with dry CH4 gas fed to the anode and H2O recirculated to the cathode, we observe that both the increase of the CH4 gas flow rate (from 10 to 20 cm3 min-1) and pressure (atmospheric, +1 and +2 bar) lead to a consistent increase of the CO2 and CO formation yield. Hence, controlling CH4 gas flow rate and pressure provides further opportunity to control the conversion and selectivity.The results achieved so far motivate us to further investigate the joint effect of the above parameters by using a membrane capable to operate under dry conditions, in a system with improved H2O management.

Anode Reaction Control for a Single-Compartment Electrochemical CO2 Reduction Reactor with a Surface-Activated Diamond Cathode.

The electrochemical reaction of carbon dioxide (CO2 ) in aqueous electrolyte solutions is attracting increasing attention for sustainable chemical production. Boron-doped diamond (BDD) electrodes have been previously shown to be very effective for the stable electrochemical production of formic acid from CO2 . Typically, the electrochemical production of formic acid by CO2 reduction (CO2 R) reaction is performed with a dual-compartment flow reactor equipped with a membrane separator. The problems caused by the membrane separator, such as scaling-up, complicated operational control and materials costs can be solved using a membrane free single-compartment reactor. Here we demonstrate anode reaction control for a single-compartment CO2 R flow reactor using a surface-activated BDD cathode and achieve a Faradaic efficiency for formic acid production of over 70 %.

Low-Cost and Scalable Electrodes for Anodic Production of Hydrogen Peroxide Via 2e- Water Oxidation

Hydrogen peroxide (H2O2) is a crucial chemical that is widely utilized in various industrial processes. The conventional anthraquinone process for H2O2 production has limitations in terms of energy consumption, high costs, and waste generation [1]. An alternative, greener and more sustainable approach is the electrochemical production of H2O2 from oxygen and water using renewable energy. Our research group has been extensively investigating the two electron (2e-) water oxidation reaction (WOR) for production of H2O2 using various electrode materials, including metal oxides, commercial carbon materials, and boron-doped diamond (BDD) [2, 3]. We also investigated the role of carbonate ions (HCO3 - and CO3 2-) in the process of water oxidation to H2O2. The enhancing effect e of CO3 2- ions on anodic H2O2 production was studied in a continuous flow reactor, where the optimal flow rate, process configuration and cell design, and chemical stabilizer were determined. Among other parameters, chemical composition and pH regime of the electrolyte were found to be crucial.Recently, we explored the use of graphite bipolar plates (BPP) as a low-cost alternative to BDD electrodes for anodic H2O2 generation [4]. Three different commercial BPPs with varying fluoropolymer content were examined, and a correlation was found between fluoropolymer content and H2O2 generation. In that study we found that a BPP sample with high fluoropolymer content resulted in a stable H2O2 production for up to 100 hours at a current density of 200 mA cm–2, with a constant faradaic efficiency of 40%. The results demonstrate that low-cost commercial carbon electrode materials can selectively oxidize water to H2O2, enabling economically viable technical applications of anodic H2O2 production.

Platinum and Palladium Nanoparticles on Boron-Doped Diamond for the Electrochemical Detection of Hydrogen Peroxide: A Comparison Study

Neurodegenerative diseases such as Alzheimer’s and traumatic brain injury currently lacks a reliable diagnosis and treatment. This is, in part, due to knowledge gaps in the understanding of the mechanisms of brain injury. Hydrogen peroxide (H2O2) and other reactive oxygen and nitrogen species (ROS/RNS) are typical byproducts of oxygen metabolism and part of the inflammatory response cascades. Any disruptions in the uptake of ROS/RNS over an extended period of time can lead to oxidative stress, further adding to the neurodegeneration. While there are several modes of detection for ROS/RNS like H2O2, one of the major drawbacks is the lack of real-time detection. Electrochemical techniques offer real-time detection, are cheap, and easy to miniaturize. Carbon-based electrodes are particularly useful in electrochemical detection due to their ability to be adapted to different measurement systems. For neurochemical detection, carbon-fiber microelectrodes are most common but tend to foul with long-term exposure in a biological environment. Novel materials like boron-doped diamond (BDD) can mitigate this issue due to its general robustness and chemical inertness while also exhibiting small capacitive current, enhanced surface roughness, and a large potential window. As with other carbon-based electrodes, BDD can be modified to increase sensitivity towards a specific analyte like H2O2. In this work, we performed a comprehensive study of BDD electrodes modified with platinum (Pt) and palladium (Pd) nanoparticles for the detection of H2O2. The modification involves a 2-step wet chemical synthesis procedure directly onto the electrode surface. We look to expand the modification process not only to novel electrode materials, but also to metals that have not been used for this purpose previously. We optimized the modification process to find the parameters that yielded the best electrode for H2O2 detection. Several factors were investigated including the double-layer capacitance, electroactive surface area, electron transfer properties, and sensitivity to H2O2, among others. It was found that the modification yielded a 308x increase in sensitivity and a 36x decrease in limit of detection (LOD) and limit of quantification (LOQ) on Pd modified BDD when compared to bare BDD. A 256x increase in sensitivity and a 26x decrease in LOD and LOQ were observed on Pt modified BDD compared to the bare BDD. We found that the BDD modified with 1 mM Pd and electrodeposited to a 5 mC charge yielded an electrode with excellent sensitivity to H2O2 and provided a LOD and LOQ well within biological concentrations. The H2O2 measurements also exhibited excellent repeatability as the relative standard deviation (%RSD) was below 10% for all modifications. The future of this work will consist of two separate steps: 1) miniaturization of these modification methods to the microelectrode scale and 2) implementation of new materials in the modification process for H2O2 detections. In general, not only does this work further exemplify the versatility of diamond electrodes for the detection of biological H2O2, but the ease of this modification process makes the use of these electrodes fairly easy in any application where H2O2 is present.