Use Of Boron-doped Diamond Research Articles

What Are the Key Factors for the Detection of Peptides Using Mass Spectrometry on Boron-Doped Diamond Surfaces?

We investigated the use of boron-doped diamond (BDD) with different surface morphologies for the enhanced detection of nine different peptides by matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS). For the first time, we compared three different nanostructured BDD film morphologies (Continuous, Nanograss, and Nanotips) with differently terminated surfaces (-H, -O, and -F) to commercially available Ground Steel plates. All these surfaces were evaluated for their effectiveness in detecting the nine different peptides by MALDI-MS. Our results demonstrated that certain nanostructured BDD surfaces exhibited superior performance for the detection of especially hydrophobic peptides (e.g., bradykinin 1-7, substance P, and the renin substrate), with a limit of detection of down to 2.3 pM. Further investigation showed that hydrophobic peptides (e.g., bradykinin 1-7, substance P, and the renin substrate) were effectively detected on hydrogen-terminated BDD surfaces. On the other hand, the highly acidic negatively charged peptide adrenocorticotropic hormone fragment 18-39 was effectively identified on oxygen-/fluorine-terminated BDD surfaces. Furthermore, BDD surfaces reduced sodium adduct contamination significantly.

Insights into antibiotic cefaclor mineralization by electro-Fenton and photoelectro-Fenton processes using a Ti/Ti4O7 anode: Performance, mechanism, and toxic chlorate/perchlorate formation

A comparative degradation of antibiotic cefaclor (CEC) between Ti/Ti4O7 and Ti/RuO2 anodes, in terms of degradation kinetics, mineralization efficiency, and formation of toxic chlorate (ClO3−) and perchlorate (ClO4−), was performed with electrochemical-oxidation (EO), electro-Fenton (EF), and photoelectro-Fenton (PEF) processes. Besides, CEC degradation by EF with boron-doped diamond (BDD) anode was also tested. Results showed CEC decays always followed pseudo-first-order kinetics, with increasing apparent rate constants in the sequence of EO < EF < PEF. The mineralization efficiency of the processes with Ti/Ti4O7 anode was higher than that of Ti/RuO2 anode, but slightly lower than that of BDD anode. Under the optimal conditions, 94.8% mineralization was obtained in Ti/Ti4O7-PEF, which was much higher than 64.4% in Ti/RuO2-PEF. The use of Ti/RuO2 gave no generation of ClO3− or ClO4−, while the use of Ti/Ti4O7 yielded a small amount of ClO3− and trace amounts of ClO4−. Conversely, the use of BDD led to the highest generation of ClO3− and ClO4−. The reaction mechanism was studied systematically by detecting the generated H2O2 and •OH. The initial N of CEC was released as NH4+ and, in smaller proportion, as NO3−. Four short-chain carboxylic acids and nine aromatic intermediates were also detected, a possible reaction sequence for CEC mineralization was finally proposed.

Electron Beam Transparent Boron Doped Diamond Electrodes for Combined Electrochemistry-Transmission Electron Microscopy.

The majority of carbon based transmission electron microscopy (TEM) platforms (grids) have a significant sp2 carbon component. Here, we report a top down fabrication technique for producing freestanding, robust, electron beam transparent and conductive sp3 carbon substrates from boron doped diamond (BDD) using an ion milling/polishing process. X-ray photoelectron spectroscopy and electrochemical measurements reveal the sp3 carbon character and advantageous electrochemical properties of a BDD electrode are retained during the milling process. TEM diffraction studies show a dominant (110) crystallographic orientation. Compared with conventional carbon TEM films on metal supports, the BDD-TEM electrodes offer superior thermal, mechanical and electrochemical stability properties. For the latter, no carbon loss is observed over a wide electrochemical potential range (up to 1.80 V vs RHE) under prolonged testing times (5 h) in acid (comparable with accelerated stress testing protocols). This result also highlights the use of BDD as a corrosion free electrocatalyst TEM support for fundamental studies, and in practical energy conversion applications. High magnification TEM imaging demonstrates resolution of isolated, single atoms on the BDD-TEM electrode during electrodeposition, due to the low background electron scattering of the BDD surface. Given the high thermal conductivity and stability of the BDD-TEM electrodes, in situ monitoring of thermally induced morphological changes is also possible, shown here for the thermally induced crystallization of amorphous electrodeposited manganese oxide to the electrochemically active γ-phase.

Recent advances of boron-doped diamond electrochemical sensors toward environmental applications

The electrocatalytic properties of boron-doped diamond (BDD) electrodes have been considered for a variety of sensing applications. The unusual electrochemical properties of BDD include a large potential window, a small background current, and better resistance to fouling than other carbon-based electrodes. The use of BDD for remediation and environmental sensing applications has recently attracted the interest of the sensor research community. This review focuses on recent developments that involve the use of BDD as an environmentally friendly sensing material for environmental analysis. The electrochemical properties of boron-doped diamond that has undergone surface modification (e.g., with metals or enzymes) will be considered. Recent achievements involving the use of BDD electrodes for detecting pesticides, mycotoxins, peroxides, and phenolic compounds are considered.

Promoting CO2 electroreduction on boron-doped diamond electrodes: Challenges and trends

CO2 electroreduction (eCO2R) into fuel products is a promising technology to mitigate the effects of greenhouse gas emissions and store renewable energy. The main metal-based electrocatalysts widely employed in CO2 reduction are characterized by high overpotentials, low stability, and unsatisfactory selectivity. As a result, a growing interest in the use of boron-doped diamond (BDD)-based electrocatalysts have been observed due to its excellent properties. This review sheds light on the techniques applied toward the eCO2R on BDD surface and the effects of the operational conditions. Particular emphasis will be given on recent advances made in the quest for enhancing the performance of BDD in eCO2R through its modification with defects insertion or functionalization with metal-based materials. The review will also present a brief overview of the challenges and directions of future research with respect to the development of different electrochemical systems for eCO2R on BDD electrodes.

Root Canal Obturation by Electrochemical Precipitation of Calcium Phosphates

Achieving adequate disinfection and preventing reinfection is the major goal in endodontic treatment. Variation in canal morphology and open porosity of dentine prevents achieving complete disinfection. Questionable biocompatibility of materials as well as a lack of sealing ability questions the usefulness of current obturation methods. With a novel disinfection approach based on the use of boron-doped diamond (BDD) electrodes having shown promising results it was the goal of this series of experiments to investigate the possibility of BDD-mediated in situ forming of a biocompatible obturation material. A combination of calcium phosphate and maleic acid was used as precursor solution while Ion Chromatography Mass Spectrometry (IC-MS), Raman spectroscopy (RAMAN), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), dye penetration and micro-computed tomography (µCT) were applied for characterizing the precipitate. It was possible to achieve a BDD-mediated precipitation of brushite in a clinically applicable timeframe. However, tight sealing of the canal system based on brushite could not be achieved.

Boron-doped diamond electrodes for the mineralization of organic pollutants in the real wastewater

The presence of recalcitrant organic compounds in wastewater poses a serious threat to the ecosystem and human health. Electrochemical advanced oxidation processes constitute a promising way for the mineralization of persistent organic compounds. They are commonly used for the transformation of organic pollutants into more biodegradable compounds or their complete removal from water. In this review, we present the recent advances in the use of boron-doped diamond (BDD) electrodes in the anodic oxidation process for the mineralization of real wastewater. First, the characteristic properties of BDD electrodes are discussed followed by the degradation mechanism. In addition, an overview on the application of BDD electrodes for mineralization of real wastewater is provided. ⋅ Electrochemical oxidation constitutes a promising way for removal of organics from water. ⋅ The boron-doped diamond (BDD) anode is recognized as the best electrode for electrooxidation of organic pollutants. ⋅ Recent advances in the use of the BDD electrode in the anodic oxidation process were summarized. ⋅ Application of the BDD anode to the mineralization of real wastewater was overviewed.

The Green Electrochemical Synthesis of Periodates and Application in API Synthesis

Periodates represent one of the most powerful and versatile oxidizers for organic synthesis. Common ways to generate it electrochemically employ lead dioxide anodes. The disintegration of these electrodes cause contaminations which impede sensitive applications.[1] The purification of periodates makes this reagent usually too costly pharmaceutical applications. With the use of boron-doped diamond a direct conversion of the inexpensive sodium and potassium iodide within an eight-electron oxidation process renders periodate. The novel process is scalable, heavy metal-free and can be conducted in batch as well as flow electrolyzers.[2] This approach can also be used for the regeneration of periodates from iodates. The process was implemented in a new synthetic approach to levetiracetam, which demonstrates the technical application and recycling of iodates in API synthesis.[3] The reactor concepts for the efficient preparation of multi-kg quantities will be presented.

Prussian Blue modified boron-doped diamond interfaces for advanced H2O2 electrochemical sensors

We report on the boron-doped diamond (BDD) electrodes modified with Prussian Blue (PB) through electrochemical synthesis, open-circuit deposition, and immobilization of Prussian Blue based nanozymes. The later allowed attaining the utmost sensitivity of the H2O2 sensor (≈0.14 A M−1 cm−2). Compared to conventional graphite electrodes modified with Prussian Blue, the use of BDD provided twenty times decreased oxygen reduction currents resulting in up to ten times increased signal-to-background ratio of the corresponding modified electrodes. The successful combination of exceptional diamond properties (including wide potential window for BDD electrodes) with advantageous performance characteristics of Prussian Blue sensing layers would open new horizons for H2O2 detection as well as biosensors elaboration.

Environmental Applications of Boron‐Doped Diamond Electrodes: 2. Soil Remediation and Sensing Applications

AbstractThe chemical stability and electrocatalytic properties of boron‐doped diamond (BDD) electrodes give rise to various applications. While wastewater treatment is the most widely studied field, the use of BDD for soil remediation and environmental sensing is currently investigated more and more. With regards to soil remediation, promising results have been reported for the treatment of soil washing solutions. Anodic oxidation using BDD at high current density allows high mineralization rates of biorefractory soil pollutants and extracting agents to be reached. At low current density, selective degradation of target pollutants has been achieved, thus allowing the reuse of extracting agents for further soil washing steps. BDD‐based electrochemical sensors have been studied for chemical oxygen demand determination, pesticide/pharmaceutical detection as well as other applications such as pH, O2 and analysis of various organic and inorganic compounds. Low detection limits, wide linear ranges and low standard deviations have been achieved. The main reasons behind the superiority of BDD sensors are the chemical stability, wide applicability and resistance of BDD towards biofouling. The beauty of BDD sensing is that it can work for a variety of organic and inorganic compounds under many physicochemical parameters.

Electrochemical Fenton-based treatment of tetracaine in synthetic and urban wastewater using active and non-active anodes

The electrochemical degradation of tetracaine hydrochloride has been studied in urban wastewater. Treatments in simulated matrix with similar ionic composition as well as in 0.050 M Na2SO4 were comparatively performed. The cell contained an air-diffusion cathode for H2O2 electrogeneration and an anode selected among active Pt, IrO2-based and RuO2-based materials and non-active boron-doped diamond (BDD). Electrochemical oxidation with electrogenerated H2O2 (EO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF) were comparatively assessed at pH 3.0 and constant current density. The pharmaceutical and its byproducts were oxidized by OH formed from water oxidation at the anode surface and in the bulk from Fenton's reaction, which occurred upon addition of 0.50 mM Fe2+ in all media, along with active chlorine originated from the anodic oxidation of Cl− contained in the simulated matrix and urban wastewater. The PEF process was the most powerful treatment regardless of the electrolyte composition, owing to the additional photolysis of intermediates by UVA radiation. The use of BDD led to greater mineralization compared to other anodes, being feasible the total removal of all organics from urban wastewater by PEF at long electrolysis time. Chlorinated products were largely recalcitrant when Pt, IrO2-based or RuO2-based anodes were used, whereas they were effectively destroyed by BDD(OH). Tetracaine decay always obeyed a pseudo-first-order kinetics, being slightly faster with the RuO2-based anode in Cl− media because of the higher amounts of active chlorine produced. Total nitrogen and concentrations of NH4+, NO3−, ClO3−, ClO4− and active chlorine were determined to clarify the behavior of the different electrodes in PEF. Eight intermediates were identified by GC-MS and fumaric and oxalic acids were quantified as final carboxylic acids by ion-exclusion HPLC, allowing the proposal of a plausible reaction sequence for tetracaine mineralization by PEF in Cl−-containing medium.

Boron Doped Diamond Paste Electrodes for Microfluidic Paper-Based Analytical Devices.

Boron doped diamond (BDD) electrodes have exemplary electrochemical properties; however, widespread use of high-quality BDD has previously been limited by material cost and availability. In the present article, we report the use of a BDD paste electrode (BDDPE) coupled with microfluidic paper-based analytical devices (μPADs) to create a low-cost, high-performance electrochemical sensor. The BDDPEs are easy to prepare from a mixture of BDD powder and mineral oil and can be easily stencil-printed into a variety of electrode geometries. We demonstrate the utility and applicability of BDDPEs through measurements of biological species (norepinephrine and serotonin) and heavy metals (Pb and Cd) using μPADs. Compared to traditional carbon paste electrodes (CPE), BDDPEs exhibit a wider potential window, lower capacitive current, and are able to circumvent the fouling of serotonin. These results demonstrate the capability of BDDPEs as point-of-care sensors when coupled with μPADs.

On the selection of the anode material for the electrochemical removal of methylparaben from different aqueous media

Parabens are widely used industrial preservatives, routinely found in wastewater along with major inorganic ions like sulfate and chloride. This work investigates the oxidation ability of three electrochemical processes in tank reactors equipped with an air-diffusion cathode to electrogenerate H2O2 on site, namely electro-oxidation (EO-H2O2), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF), to degrade aqueous solutions of methylparaben (MeP) at pH 3.0. Their performance using boron-doped diamond (BDD), Pt or two kinds of dimensionally stable anodes (DSA®) has been compared from the analysis of mineralization profiles and decay kinetics in the presence of sulfate and/or chloride ions. The use of BDD ensured the overall mineralization in all three processes according to the sequence: PEF>EF>EO-H2O2, thanks to the contribution of BDD(OH), OH and UVA light. Pt and DSA® became an interesting alternative in PEF, with slower organic matter removal but similar final mineralization percentages, being much less powerful than BDD in EO-H2O2. The presence of Cl− was beneficial in the latter process, due to the formation of active chlorine as an additional oxidant that caused a much faster decay of MeP. Conversely, it became significantly detrimental in EF due to the partial destruction of H2O2 and OH in the bulk by active chlorine and Cl−, respectively. The oxidation power of PEF was so high that similar fast, complex decay kinetics was found in all media regardless of the anode, although the mineralization was decelerated owing to the accumulation of chlorinated by-products. GC-MS and HPLC analysis allowed the identification of up to seven aromatic MeP derivatives in sulfate+chloride mixtures, including three non-chlorinated compounds also found in pure sulfate medium. These molecules were gradually transformed into oxalic acid, along with four chlorinated aliphatic carboxylic acids in Cl−-containing media.

Quasi-Real Time Quantification of Uric Acid in Urine Using Boron Doped Diamond Microelectrode with in Situ Cleaning

We report herein an innovative electrochemical (EC) technique based on boron doped diamond (BDD) microelectrodes which enable the fast determination of uric acid (UA) concentrations in urine. On the basis of fast cyclic voltammetry (CV), the technique was assessed in human urine samples and compared successfully using routine spectrophotometric diagnosis. The approach relies on the use of BDD's superior properties such as low background current, low adsorption of species, long-term stability, and antifouling capabilities using electrochemical reactivation. Moreover, the article also describes an in situ activation technique, where the electrodes were reactivated within human urine, thereby opening the way toward automatic quantification of UA with in situ cleaning. The time taken to quantify UA concentration and cleaning remains below 0.5 s. Two analytic models were derived, based on different concentrations of ascorbic acid (AA) and uric acid, consisting of 2 s order calibration curves. Solving the second order equation enables the direct estimation of UA concentration, and values demonstrated good accuracy when compared with spectrophotometric measurements.

Platinum Electrodeposition on Conductive Diamond Powder and Its Application to Methanol Oxidation in Acidic Media

Boron-doped diamond (BDD) powder is shown to be a possible alternative to carbon as a support material for fuel cell electrocatalysts such as platinum. In this work, a Pt/BDD powder electrocatalyst was prepared via electrochemical deposition of platinum, and the electrochemical behavior was compared with that for Pt/graphite powder. Electrodes were prepared by coating polycrystalline BDD films with these electrocatalysts, with Nafion solution as a binder, and the activities for methanol oxidation were found to be comparable. The use of BDD resulted in a much higher stability of the catalyst under severe anodic conditions. Steady-state and long-time methanol oxidation polarization measurements, performed in the “floating electrode” configuration in acidic media, showed that platinum on BDD powder was less sensitive to deactivation, presumably due to CO poisoning, than was platinum on graphite powder.

The Role of the Characteristics of p-Si BDD Anodes on the Efficiency of Wastewater Electro-oxidation Processes

During recent years, many works have been published concerning the use of boron-doped diamond (BDD) anodes in the electrolyses of synthetic and actual wastewater. Most of these works have been focused on the feasibility of the use of conductive-diamond electrochemical oxidation (CDEO) to treat different types of pollutants. Consequently, the effects of the wastewater characteristics and those of the operation conditions have been exhaustively evaluated. However, the effects of the characteristics of conductive-diamond electrodes in the bulk electrolyses results have not been discussed in detail, because the existing studies have been typically carried out using just one type of conductive-diamond surface. In this context, this work tries to clarify the role of several diamond characteristics (boron doping, sp 3 /sp 2 ratio, diamond-layer thickness, surface finishing, and substrate resistivity) on the performance of the CDEO of synthetic wastewaters polluted with phenol (as a model organic pollutant). Commercial lots provided by an important conductive-diamond manufacturing company and simple statistical tools have been used to establish the main conclusions. Results show that phenol oxidation is strongly influenced by the conductive-diamond characteristics, particularly by the roughness of the surface. The rougher the surface, the better the efficiencies obtained. These results have been interpreted in terms of the oxidation mechanisms involved in the CDEO.

Electrochemical degradation of clofibric acid in water by anodic oxidation: Comparative study with platinum and boron-doped diamond electrodes

Aqueous solutions containing the metabolite clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid) up to close to saturation in the pH range 2.0–12.0 have been degraded by anodic oxidation with Pt and boron-doped diamond (BDD) as anodes. The use of BDD leads to total mineralization in all media due to the efficient production of oxidant hydroxyl radical (OH). This procedure is then viable for the treatment of wastewaters containing this compound. The effect of pH, apparent current density, temperature and metabolite concentration on the degradation rate, consumed specific charge and mineralization current efficiency has been investigated. Comparative treatment with Pt yields poor decontamination with complete release of stable chloride ion. When BDD is used, this ion is oxidized to Cl2. Clofibric acid is more rapidly destroyed on Pt than on BDD, indicating that it is more strongly adsorbed on the Pt surface enhancing its reaction with OH. Its decay kinetics always follows a pseudo-first-order reaction and the rate constant for each anode increases with increasing apparent current density, being practically independent of pH and metabolite concentration. Aromatic products such as 4-chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol are detected by gas chromatography–mass spectrometry (GC–MS) and reversed-phase chromatography. Tartronic, maleic, fumaric, formic, 2-hydroxyisobutyric, pyruvic and oxalic acids are identified as generated carboxylic acids by ion-exclusion chromatography. These acids remain stable in solution using Pt, but they are completely converted into CO2 with BDD. A reaction pathway for clofibric acid degradation involving all these intermediates is proposed.

Electrochemical Behavior of Cobalt Oxide Films Deposited at Conductive Diamond Electrodes

The oxidation of Co(II) at a boron-doped diamond (BDD) electrode was investigated by use of anodic voltammetry. The results shows that this reaction takes place by a mechanism similar to that of cobalt metal oxidation in alkaline media. The voltammetric curves evidence a strong enhancement of the oxygen evolution current in the presence of Co(II). This behavior is consistent with cobalt oxide formation at the diamond electrode surface. Based upon these results, a simple, straightforward method for the production of high activity films on BDD electrode surfaces is demonstrated. The study of the electrochemical behavior in 1 M NaOH shows that the electrodes thus obtained exhibit promising, stable electrocatalytic performance for oxygen evolution, comparing well with those of thermally deposited cobalt electrodes. The use of BDD as a substrate for the electrocatalytic layers allows the deposition of isolated particles or discontinuous films, thus maximizing the utilization of the catalyst by avoiding the need for thick films. © 2003 The Electrochemical Society. All rights reserved.

Sonoelectrochemistry at highly boron-doped diamond electrodes: silver oxide deposition and electrocatalysis in the presence of ultrasound

The use of boron-doped diamond has a considerable impact in electrochemistry owing to the wide potential range accessible, low background currents, extreme hardness, and the ease of chemical modification of diamond surfaces. It is shown here that, although the electrodeposition of silver metal is known to yield very poorly adhering films with a poor electrical contact, a silver oxysalt deposit formed on anodically pre-treated diamond surfaces adheres strongly with good electrical contact. The deposit is stable even in the presence of ultrasound. Voltammetric and XPS studies reveal that the silver oxide deposit, in contrast to the silver metal deposit, is efficiently stripped from the diamond surface by applying a sufficiently negative potential. The silver oxysalt Ag7O8NO3, deposited onto two types of boron-doped diamond electrodes, a 50 μm thick polycrystalline thin film deposited on a tungsten substrate and a polished free standing diamond plate, is shown to act as an electrocatalyst for oxygen evolution and for the oxidation of toluene. This development opens up the possibility of boron-doped diamond being applied as an inert and conducting substrate material for a wide range of oxidic materials, which can then be utilised as active electrocatalysts at high applied potentials.

Different distribution and regulation of chloride channels in mammalian and amphibian skeletal muscles

Aqueous solutions containing the metabolite clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid) up to close to saturation in the pH range 2.0–12.0 have been degraded by anodic oxidation with Pt and boron-doped diamond (BDD) as anodes. The use of BDD leads to total mineralization in all media due to the efficient production of oxidant hydroxyl radical (OH). This procedure is then viable for the treatment of wastewaters containing this compound. The effect of pH, apparent current density, temperature and metabolite concentration on the degradation rate, consumed specific charge and mineralization current efficiency has been investigated. Comparative treatment with Pt yields poor decontamination with complete release of stable chloride ion. When BDD is used, this ion is oxidized to Cl2. Clofibric acid is more rapidly destroyed on Pt than on BDD, indicating that it is more strongly adsorbed on the Pt surface enhancing its reaction with OH. Its decay kinetics always follows a pseudo-first-order reaction and the rate constant for each anode increases with increasing apparent current density, being practically independent of pH and metabolite concentration. Aromatic products such as 4-chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol are detected by gas chromatography–mass spectrometry (GC–MS) and reversed-phase chromatography. Tartronic, maleic, fumaric, formic, 2-hydroxyisobutyric, pyruvic and oxalic acids are identified as generated carboxylic acids by ion-exclusion chromatography. These acids remain stable in solution using Pt, but they are completely converted into CO2 with BDD. A reaction pathway for clofibric acid degradation involving all these intermediates is proposed.