Boron-doped Diamond Film Electrode Research Articles

Photocatalytic Degradation of Diclofenac in Tap Water on TiO2 Nanotubes Assisted with Ozone Generated from Boron-Doped Diamond Electrode

Degradation of pharmaceuticals in water by TiO2 photocatalysis often suffers from low efficiency due to low activity and mass transfer limitation. In this work, diclofenac removal in tap water was performed by photocatalysis on TiO2 nanotube growth on Ti mesh substrate assisted by ozone (O3), which was generated from a hole-arrayed boron-doped diamond (HABDD) film electrode. The vertically oriented TiO2 nanotubes were used as the heterogeneous photocatalyst. The HABDD, as a self-standing diamond electrode, was designed and custom-made by MWCVD technology. The microstructures and crystalline of the TiO2 nanotubes and HABDD were characterized by a scanning electronic micrograph (SEM) and X-ray diffraction (XRD). Unlike other ozone generation methods, direct generation of ozone in the flowing water was applied in the photocatalysis process, and its effect was discussed. The diclofenac removal performance of the electrochemical-photocatalytic system was studied depending on O3 generation efficiency, flowing rate, and the initial diclofenac concentration. The enhanced degradation effect from O3 molecules on TiO2 photocatalysis was attributed to the larger active surface area, the increased photo-generated charge separation rate, and the contact area of O3. The degradation efficiency in the combined electrochemical-photocatalytic TiO2/O3/UV system was higher than that of the O3/UV and TiO2/UV routes individually. Furthermore, a theoretical calculation was used to analyze the TiO2/O3 interface in aqueous media in terms of the final energy. This system created an almost in situ feeding channel of oxidants in the TiO2 photocatalysis process, thus increasing photocatalytic efficiency. This synergetic system is promising in the treatment of pharmaceuticals in water.

Influence of boron doped level on the electrochemical behavior and seawater salinity detection of boron doped diamond film electrodes

Boron doped diamond (BDD) film electrodes have a good application prospect in the field of seawater salinity detection. However, the influence mechanism of boron doping level (given by B/C ratio) on seawater salinity detection limited its application. In this paper, microstructure-phase-electrochemical relationships in BDD film electrodes were systematically investigated, aiming to reveal the effect of boron content on seawater salinity measurement, and lay a foundation for practical application of BDD film electrodes. With the increase of the boron doping, the content of non-diamond phase increased, while the crystallinity and the grain size of diamond decreased. Meanwhile, when the B/C ratio of BDD electrode reached 10000 ppm, they had the largest electroactive surface areas (EASA) and the smallest diffusion resistance, and their electrochemical performance was optimal in this study. In addition, BDD film electrode exhibited fast heterogeneous electron transfer in both internal Fe(CN)6−3/−4 and external Ru(NH3)6+2/+3 redox systems. Under the optimal parameter setting, the maximum signal response of BDD electrode at 40 ‰ was 69 mA/cm2 and the measurement error was less than 0.81 ‰. Appropriate proportion of sp2-C and B-sp3-C phases can significantly improve the detection performance of BDD electrode.

Fabrication of Boron-Doped Diamond Film Electrode for Detecting Trace Lead Content in Drinking Water.

This work aimed to fabricate a boron-doped diamond film electrode for detecting trace amounts of lead in drinking water so as to safeguard it for the public. Available detectors suffer from high costs and complex analytical processes, and commonly used electrodes for electrochemical detectors are subject to a short life, poor stability, and secondary pollution during usage. In this work, a boron-doped diamond (BDD) electrode was prepared on a porous titanium substrate, and the microstructure and electrochemical properties of the BDD electrode were systematically studied. Moreover, the stripping parameters were optimized to obtain a better signal response and determine the detection index. As a result, diamond particles were closely arranged on the surface of the BDD electrode with good phase quality. The electrode showed high electrochemical activity, specific surface area, and low charge transfer resistance, which can accelerate the stripping reaction process of Pb2+. The BDD electrode presented a low detection limit of 2.62 ppb for Pb2+ under an optimized parameter set with an enrichment time of 150 s and a scanning frequency of 50 Hz. The BDD electrode also has good anti-interference ability. The designed BDD electrode is expected to offer a reliable solution for the dilemma of the availability of metal electrodes and exhibits a good application prospect in the trace monitoring of Pb2+ content in drinking water.

Electrochemical oxidation of Reactive Blue 19 on boron-doped diamond anode with different supporting electrolyte

• BDD-PS EAOP was used to treat RB-19 simulated dye wastewater. • Persulfate electrolyte has excellent temperature adaptability. • BDD-PS system can degrade organics efficiently with low energy consumption. • BDD-PS system can effectively degrade wastewater in a wide pH range (1.5-12). In this study, boron-doped diamond film (BDD) electrode with high sp 3 /sp 2 ratio was prepared by hot filament chemical vapor deposition (HFCVD). A systemic electrochemical advanced oxidation processes (EAOPs) study was carried out by using BDD anode and three different supporting electrolyte (Na 2 SO 4 , NaCl, and Na 2 S 2 O 8 ) to degrade the high volume and high concentration (0.5 L, 100 mg L -1 ) simulated anthraquinone Reactive Blue 19 (RB-19) dye wastewater. BDD-PS (persulfate) system was used to study the effects of current density, initial pH and solution temperature on decolorization degree and mineralization rate (TOC removal rate) by comparing with other two electrolytes (NaCl and Na 2 SO 4 ). BDD activated PS could effectively degrade RB-19 in a large pH range (1.5-12), and higher degradation efficiency and lower energy consumption under strong acid and alkali conditions than traditional BDD-EO based on Na 2 SO 4 and NaCl electrolytes. More interestingly, at the temperature of 70 ℃, the TOC removal reached 90% in 30 min and 100% in 60 min, which is apparently higher than that under NaCl and Na 2 SO 4 as electrolytes. Our work indicates BDD-PS technology can effectively degrade organic wastewater, which has the characteristics of efficiently and better pH applicability, and more importantly which can decompose RB-19 with the aid of increase of temperature.

In Situ ATR-IR Observation of the Electrochemical Oxidation of a Polycrystalline Boron-Doped Diamond Electrode in Acidic Solutions

Electrochemical surface oxidation in acidic solutions was investigated on a boron-doped diamond film electrode, fabricated on a silicon prism, using attenuated total reflection infrared spectroscopy. At positive potentials above +1.3 V (reversible hydrogen electrode, RHE), the bands of surface oxygen species appear at 1745 and 1250 cm–1. Since these bands exhibit no isotope shift in deuterium solution, they are assigned to the C═O and C–O stretching modes, respectively. These bands have the maximum intensity at +3.3 V (RHE) and reversibly disappear around +0.9 V (RHE) in the potential step to the negative direction. The potentials at which the bands appear and disappear are identical to those of the anodic and cathodic peaks of the cyclic voltammogram, respectively.

Characterization and electrochemical behavior of spherical boron-doped diamond film electrode

The boron-doped diamond film electrode was prepared on the tungsten carbide (WC) sphere using the microwave plasma chemical vapor deposition method. Two electrodes of different sizes were obtained by the encapsulation of the diamond coated spheres. A flexible lead wire was utilized instead of the rigid connection as usual. Scanning electronic microscopy, Raman spectroscopy, and electrochemical measurements were employed to characterize the morphology, the composition of the films, and electrochemical behavior, respectively. These electrodes have a wide potential window of 3 V in phosphate buffer saline solution. The electrode with a diameter of 800 μm exhibits a low dopamine detection concentration of 10 μmol l−1, while the electrode with a diameter of 200 μm indicates the faster electrode response and the higher sensitivity with a microelectrode diffusion mode. A WC sphere with the boron-doped diamond film is expected to be used for the electrode to ensure full contact with the organism.

Boron-doped Diamond Film Electrode as Voltammetric Sensor for Cetirizine

Boron-doped Diamond Film Electrode as Voltammetric Sensor for Cetirizine

Facet-Dependent Temporal and Spatial Changes in Boron-Doped Diamond Film Electrodes due to Anodic Corrosion

The progression of corrosion in polycrystalline boron-doped diamond (BDD) thin film electrode is explored as the electrode undergoes high-current density anodic treatments with organic compounds. Micro-Raman spectroscopy and spectral mapping indicate that anodic corrosion is initiated by the conversion of sp3 diamond to amorphous sp2 carbon at the surface, which are then removed after longer anodic treatment. Polarized Raman analysis reveals that corrosion-induced changes on the surface are specific to (100)-grain facets and (111)-grain edges. X-ray photoelectron spectroscopic measurements suggest that carbonyl groups consequently form on these specific sites and act as an intermediate toward the etching of the surface. This process exposes and subsequently removes the subsurface boron atoms, thus reducing the doping density. The observed crystal grain orientation dependence of the corrosion process provides new insights toward a better understanding of degradation in BDD electrodes.

Fluorination of Boron-Doped Diamond Film Electrodes for Minimization of Perchlorate Formation.

This research investigated the effects of surface fluorination on both rates of organic compound oxidation (phenol and terephthalic acid (TA)) and ClO4- formation at boron-doped diamond (BDD) film anodes at 22 °C. Different fluorination methods (i.e., electrochemical oxidation with perfluorooctanoic acid (PFOA), radio frequency plasma, and silanization) were used to incorporate fluorinated moieties on the BDD surface, which was confirmed by X-ray photoelectron spectroscopy (XPS). The silanization method was found to be the most effective fluorination method using a 1H,1H,2H,2H-perfluorodecyltrichlorosilane precursor to form a self-assembled monolayer (SAM) on the oxygenated BDD surface. The ClO4- formation decreased from rates of 0.45 ± 0.03 mmol m-2 min-1 during 1 mM NaClO3 oxidation and 0.28 ± 0.01 mmol m-2 min-1 during 10 mM NaCl oxidation on the BDD electrode to below detectable levels (<0.12 μmoles m-2 min-1) for the BDD electrode functionalized by a 1H,1H,2H,2H-perfluorodecyltrichlorosilane SAM. These decreases in rates corresponded to 99.94 and 99.85% decreases in selectivity for ClO4- formation during the electrolysis of 10 mM NaCl and 1 mM NaClO3 electrolytes, respectively. By contrast, the oxidation rates of phenol were reduced by only 16.3% in the NaCl electrolyte and 61% in a nonreactive 0.1 M KH2PO4 electrolyte. Cyclic voltammetry with Fe(CN)63-/4- and Fe3+/2+ redox couples indicated that the long fluorinated chains created a blocking layer on the BDD surface that inhibited charge transfer via steric hindrance and hydrophobic effects. The surface coverages and thicknesses of the fluorinated films controlled the charge transfer rates, which was confirmed by estimates of film thicknesses using XPS and density functional theory simulations. The aliphatic silanized electrode also showed very high stability during OH• production. Perchlorate formation rates were below the detection limit (<0.12 μmoles m-2 min-1) for up to 10 consecutive NaClO3 oxidation experiments.

Electrochemical decolorization of dye wastewater by surface-activated boron-doped nanocrystalline diamond electrode

Complex organics contained in dye wastewater are difficult to degrade and often require electrochemical advanced oxidation processes (EAOPs) to treat it. Surface activation of the electrode used in such treatment is an important factor determining the success of the process. The performance of boron-doped nanocrystalline diamond (BD-NCD) film electrode for decolorization of Acid Yellow (AY-36) azo dye with respect to the surface activation by electrochemical polarization was studied. Anodic polarization found to be more suitable as electrode pretreatment compared to cathodic one. After anodic polarization, the originally H-terminated surface of BD-NCD was changed into O-terminated, making it more hydrophilic. Due to the oxidation of surface functional groups and some portion of sp2 carbon in the BD-NCD film during anodic polarization, the electrode was successfully being activated showing lower background current, wider potential window and considerably less surface activity compared to the non-polarized one. Consequently, electrooxidation (EO) capability of the anodically-polarized BD-NCD to degrade AY-36 dye was significantly enhanced, capable of nearly total decolorization and chemical oxygen demand (COD) removal even after several times of re-using. The BD-NCD film electrode favored acidic condition for the dye degradation; and the presence of chloride ion in the solution was found to be more advantageous than sulfate active species.

Determination of prazosin in pharmaceutical samples by flow injection analysis with multiple-pulse amperometric detection using boron-doped diamond electrode

This work describes the development of a simple, fast and low-cost method for determining prazosin (PRA) in pharmaceutical samples by flow injection analysis with multiple-pulse amperometric (FIA-MPA) detection using a boron-doped diamond film electrode. Electrochemical detection of PRA was optimized in phosphate buffer pH 4.0 by cyclic voltammetry, in which PRA presented two oxidation processes around at 0.97 and 1.40 V versus Ag/AgCl (3.0 mol L−1 KCl). In these conditions, PRA also showed one reduction process at −0.75 V that is dependent on the oxidation processes. Thus, the determination of PRA by FIA-MPA detection consisted on the application of a two-potential waveform, E 1 (generator potential) = 1.6 V/400 ms and E 2 (collector potential) = −1.0 V/30 ms, with sample loop of 150 μL and flow rate of 3.0 mL min−1. The method showed good repeatability (RSD < 3.0 %) and high analytical frequency (70 injections per h). The working linear range was obtained from 2 to 200 μmol L−1 with a limit of detection of 0.5 μmol L−1. The recovery tests in all samples were approximately 100 %, and the results were compared with chromatographic methods.

Amperometric tyrosinase biosensor based on boron-doped nanocrystalline diamond film electrode for the detection of phenolic compounds

A novel tyrosinase amperometric biosensor based on boron-doped nanocrystalline diamond (BDND) film electrode has been developed for the detection of phenolic compounds. Amine-terminated BDND surface was achieved via a direct photochemical reaction with allylamine. The tyrosinase was then covalently immobilized on the amine-terminated diamond film electrode surface. The effects of pH and applied potential on the performance of tyrosinase amperometric biosensor were investigated. The biosensor showed an optimum response at a pH of 6.5 and at an applied potential of −100 mV. It also exhibited good analytical performances to phenolic compounds in terms of sensitivity, detection limit, and stability. The tyrosinase-modified BDND film electrode exhibited a rapid response to the changes in the substrate concentration for all the phenolic compounds tested and reached 95 % of steady-state current in about 10 s. It is attributed to the high loading of tyrosinase and the rapid electron transfer between the tyrosinase and BDND film electrode surface. The tyrosinase-modified BDND film electrode showed high sensitivity with 184.0, 95.6, and 552.3 mA M−1 cm−2 and a linear response range of 10.0–120.0, 5.0–120.0, and 30.0–120.0 μM for phenol, catechol, and 4-chlorophenol, respectively.

Enhanced electrochemical oxidation of organic pollutants by boron-doped diamond based on porous titanium

The main aim of the present study was to explore the potential of boron-doped diamond (BDD) film electrode on porous titanium (Ti) substrate to promote the electrochemical oxidation of organic pollutants. Porous Ti endowed the Ti/BDD film three-dimensional porous structure. The electrochemical effective surface area for porous Ti/BDD anode was 8.37cm2/cm2, 3.2 times as much as that of two-dimensional flat Ti/BDD electrode. Furthermore, the generation ability and rate of hydroxyl radical (OH) on porous BDD electrode were enhanced due to the porous structure of BDD film. The step currents on porous Ti/BDD were about 2 times of those on flat Ti/BDD electrode from chronoamperometry curves, porous Ti/BDD exhibited superior indirect electrochemical oxidation ability. The results of electrodegradation of several typical organic pollutants (oxalic acid, phenol, sodium dodecylbenzene sulfonate, xylenol orange) revealed that current efficiencies on porous Ti/BDD electrode were about 30% higher compared with flat BDD electrode, corroborating the enhanced of electrochemical oxidation as the introduction of porous Ti substrate. Moreover, the discrepancy between promotion of COD removal rate and enhancement of OH was discussed.

Electrochemical Detection of Antibiotics in Environmental Matrices Using Functionalized Boron-Doped Diamond Electrodes

Ciprofloxacin (CIP) is a widely prescribed fluoroquinolone antibiotic used in health care and agricultural industries to treat against human and animal bacterial diseases. Due to the fact that only a portion of the antibiotic is metabolized during administration to humans and livestock, large loads of CIP are delivered to watersheds via agricultural runoff or wastewater discharge. The presence of antibiotics in the environment may cause the proliferation of bacterial drug resistance. For this reason the development of sensitive and selective sensors to monitor antibiotics in the environment is an active area of research. In this work, we discuss the development of selective electrochemical sensors through the functionalization of boron-doped diamond (BDD) film electrodes. Sensors are developed by functionalizing the BDD surface with a layer of multi-walled carbon nanotubes (MWCNTs) and a templated-Nafion film. Experiments show that the CIP templated-Nafion film enabled CIP detection at the BDD surface by modifying the polymer pore size and electrostatically excluding anionic species. This templating procedure was shown to be effective for selectively detecting CIP in the presence of other fluoroquinolones (i.e., amoxicillin) and other non-target water constituents (i.e., Cl-, Ca2+, salicylic acid). Additionally, the addition of MWCNTs significantly lowered the detection limit by increasing the specific surface area of the sensor and by promoting specific adsorptive interactions between CIP and surface functional groups of the MWCNTs. Differential pulse voltammetry scans showed that a detection limit as low as 5 nM could be achieved at a pH of 4.5. Linear current response with respect to CIP concentration was achieved up to concentrations of 15 μM, and the peak current response was on the order of 2.8 μA/μM. This sensor platform was extended to other fluoroquinolone antibiotics in order to develop sensor arrays for the simultaneous detection of a number of antibiotics in environmental matrices.

Oxidative and Reductive Detection Modes for Determination of Nitrophenols by High-Performance Liquid Chromatography with Amperometric Detection at a Boron Doped Diamond Electrode

ABSTRACTHigh performance liquid chromatography with electrochemical detection using a wall-jet arrangement with a working boron-doped diamond film electrode was used for the determination of 2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol using reduction and oxidation modes. The optimal conditions for separation at a C18 reverse phase column (125 × 4 millimeters, 5 micrometers) and amperometric detection of these nitrophenols were determined. Acetate buffer (0.05 mole per liter pH 4.7/methanol 58/42, v/v) was chosen as the mobile phase for cathodic detection at the potential of −1.2 volts. The linear dynamic range was 2 × 10−6 to 1 × 10−4 mole per liter and the limits of detection were from 0.7 to 1.2 micromole per liter. For anodic detection, the mobile phase was 0.05 mole per liter phosphate buffer pH 6.75/methanol (65/35, v/v) at a detection potential of +1.3 volts. The linear dynamic range was from 2 × 10−6 to 1 × 10−4 mole per liter with limits of detection from 0.6 to 1.5 micromoles per liter. The method was successfully employed for direct determination of nitrophenols in drinking and river water with limits of detection between 0.7 and 1.8 micromoles per liter.

Electrochemical determination of adrenaline in human urine using a boron-doped diamond film electrode

Abstract A simple and sensitive square-wave voltammetric method for the determination of adrenaline on unmodified boron-doped diamond film electrode was developed. Adrenaline exhibited the quasi-reversible behavior with oxidation peak on the forward scan at + 0.75 V and smaller reduction peak on the reverse scan at − 0.10 V vs. Ag/AgCl electrode in 0.5 M HClO4. The effect of supporting electrolyte, pH and scan rate on the current response of adrenaline was examined to select the optimum experimental conditions. At optimized square-wave voltammetric parameters (amplitude of 100 mV, frequency of 50 Hz and step potential of 5 mV), the linear concentration range from 0.7 to 60 μM (R2 = 0.998, number of measurements n = 6), the excellent repeatability (relative standard deviation of 3.5% for n = 50) and the detection limit of 0.21 μM were achieved without any chemical modification and pretreatment of working electrode. The practical application of method was demonstrated in the determination of adrenaline in spiked human urine samples with satisfactory recoveries (98 to 102%).

Investigation on Electrochemically Cathodic Polarization of Boron-Doped Diamond Electrodes and Its Influence on Lead Ions Analysis

The purpose of this paper is to further understand the dependence of the electrochemical activity of a boron-doped diamond (BDD) film electrode on its surface boron doping concentration and the pretreatment applied to its surface. An electrochemically cathodic polarization (−3 V vs. SCE) with a varying polarization duration (5–50 min) was carried separately out to three types of BDDs with a boron doping level of 700, 2500, 8000 ppm in 0.5 M H2SO4 solution. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to evaluate surface activity of the BDDs with and without cathodic polarizations by using 1.0 mM Fe(CN)63−/4−. Moreover, the surface activity of the polarized BDD electrodes was examined further by using anodic stripping voltammetry to detect a series of known concentrations of Pb2+. Our results indicated that the applied cathodic polarization significantly improved the surface activity of the as-received BDD, and exhibited more active effect on the surface of a higher boron doping level BDD compared to a lower boron doping level BDD, thereby improving the ability of the polarized BDDs to detect trace Pb(II) in aqueous solutions by anodic stripping voltammetry.

Voltammetric method for sensitive determination of herbicide picloram in environmental and biological samples using boron-doped diamond film electrode

The voltammetric behavior and determination of picloram, a member of a pyridine herbicide family, was for the first time investigated on a boron doped diamond film electrode using cyclic and differential pulse voltammetry. The influence of supporting electrolyte and scan rate on the current response of picloram was examined to select the optimum experimental conditions. It was found that picloram provided one well-shaped oxidation peak at very positive potential (+1.5V vs. Ag/AgCl electrode) in strong acidic medium. At optimized differential pulse voltammetric parameters, the current response of picloram was proportionally linear in the concentration range from 0.5 to 48.07μmolL−1 and the low limit of detection of 70nmolL−1 as well as good repeatability (relative standard deviation of 2.6% at 10μmolL−1 for n=11) were obtained on unmodified boron-doped diamond film electrode. The proposed method was successfully applied in analysis of environmental (tap and natural water) and biological (human urine) samples spiked with picloram with good accuracy (relative standard deviations less than 5% for all samples, n=5). By this way, the boron-doped diamond could introduce a green (environmentally acceptable) alternative to mercury electrodes for the monitoring of herbicides.

The microstructure and electrochemical properties of boron-doped nanocrystalline diamond film electrodes and their application in non-enzymatic glucose detection

Boron-doped nanocrystalline diamond (BDND) films were deposited on Si(100) by microwave plasma chemical vapor deposition using trimethyl boron as boron source. The surface morphology, microstructure, and electrochemical properties of the BDND films were investigated. Cyclic voltammograms indicated that the BDND film electrode exhibited good reversibility and repeatability of electrode reaction using [Fe(CN)6]3−/4− as redox couple. The non-enzymatic glucose sensor based on the as-prepared BDND film electrode without any modification was developed, and the selective detection of glucose in alkaline solution containing interference species of ascorbic acid and uric acid was demonstrated. The results showed that glucose can be directly oxidized with a wide linear range and high sensitivity, and selectively detected in the presence of uric acid and ascorbic acid in alkaline solution using the as-prepared BDND film electrode.

Highly Efficient, Ultra‐Low Energy Consumption Process for Phenol Wastewater Treatment with Ultra‐Low Carbon Emission

AbstractPhenol is one of the main pollutants in phenol wastewater and has been proved non‐biodegradable. In this study, based on strongly ring‐opening capability of boron doped diamond film electrode, a highly efficient and energy‐saving method with ultra‐low carbon emission is established through a combination of electrochemical oxidation and biological degradation. On one hand, electrochemical oxidation as pretreatment can solve the critical problem that phenol wastewater is a biological recalcitrant. On the other hand, the relatively low current efficiency during the late stage of electrochemical oxidation can be solved by follow‐up biological treatment, thus reduce the energy consumption and the cost significantly. More importantly, the carboxylic acids (oxidized from phenol) can be fully used as carbon source (no additional carbon source is added) for microbial growth instead of being oxidized to carbon dioxide and water through selecting optimizing sequencing batch reactor access time, so the carbon emission is greatly reduced. The results showed that it can save about 76.5% energy consumption and about 51.2% chemical oxygen demand can be used to maintain microorganism self‐reproduction. This is significant that this combined technology not only runs highly effectively at low cost, but also reduces the emission of greenhouse gas, carbon dioxide, thus environment friendly with wide application prospects.