Electrochemical incineration of dimethyl phthalate by anodic oxidation with boron-doped diamond electrode

The anodic oxidation of aqueous solutions containing dimethyl phthalate （DMP） up to 125 mg/L with sodium sulfate （Na2SO4） as supporting electrolyte within the pH range 2.0-10.0 was studied using a one-compartment batch reactor employing a boron-doped diamond （BDD） as anode. Electrolyses were carded out at constant current density （1.5-4.5 mA/cm^2）. Complete mineralization was always achieved owing to the great concentration of hydroxyl radical （-OH） generated at the BDD surface. The effects of pH, apparent current density and initial DMP concentration on the degradation rate of DMP, the specific charge required for its total mineralization and mineralization current efficiency were investigated systematically. The mineralization rate of DMP was found to be pH-independent and to increase with increasing applied current density. Results indicated that this electrochemical process was subjected, at least partially, to the mass transfer of organics onto the BDD surface. Kinetic analysis of the temporal change of DMP concentration during electrolysis determined by High Performance Liquid Chromatography （HPLC） revealed that DMP decay under all tested conditions followed a pseudo first-order reaction. Aromatic intermediates and generated carboxylic acids were identified by Gas Chromatography- Mass Spectrometry （GC-MS） and a general pathway for the electrochemical incineration of DMP on BDD was proposed.

Synthesis and characterization of p-type boron-doped IIb diamond large single crystals

High-quality p-type boron-doped IIb diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond.

Electrochemical Characteristics and Applications of Boron-Doped Polycrystalline Diamond Film Electrodes

The elcetrochemical characteristics of boron doped polycrystalline diamond thin film (BDF) electrode 4×4 mm 2 in size were studied using cyclic voltammetry and potentiostatic method. The diamond electrode exhibits adequate electrochemical activity and its response current changes linearly with K 3Fe(CN) 6 concentrations. The response current is proportional to the square root of the scan rate, reflecting mass transport controlled by planar diffusion. Stable mass transport can be quickly established within 4s. The BDF electrode provides good resolving power for the determination of lead and cadmium and gives satisfactory results in the analysis of pure water sample.

Synthesis of Boron-doped Diamond/Porous Ti Composite Materials——Effect of Carbon Concentration

Highly boron-doped diamond films were deposited on porous titanium substrates by hot filament chemical vapor deposition technique. The morphology variation of highly boron-doped diamond films grown on porous titanium substrates was investigated, and the effects of carbon concentration on nucleation density and diamond growth were also studied. The continuous change of surface morphology and structure of diamond film were characterized by scanning electron microscopy. The structures of diamond film and interlayer were analyzed by X-ray diffraction. The quality of boron-doped diamond film was confirmed by visible Raman spectroscopy. The experimental results reveal that surface morphology and quality of boron-doped diamond films are various due to the change of carbon concentration. The thickness of intermediate layer decreases with the carbon concentration increasing.

Ohmic and Schottky contacts of hydrogenated and oxygenated boron-doped single-crystal diamond with hill-like polycrystalline grains

Hill-like polycrystalline diamond grains(HPDGs)randomly emerged on a heavy boron-doped p+single-crystal diamond(SCD)film by prolonging the growth duration of the chemical vapor deposition process.The Raman spectral results confirm that a relatively higher boron concentration(~1.1×10^(21) cm^(-3))is detected on the HPDG with respect to the SCD region(~5.4×10^(20) cm^(-3)).It demonstrates that the Au/SCD interface can be modulated from ohmic to Schottky contact by varying the surface from hydrogen to oxygen termination.The current-voltage curve between two HPDGs is nearly linear with either oxygen or hydrogen termination,which means that the HPDGs provide a leakage path to form an ohmic contact.There are obvious rectification characteristics between oxygen-terminated HPDGs and SCD based on the difference in boron doping levels in those regions.The results reveal that the highly boron-doped HPDGs grown in SCD can be adopted as ohmic electrodes for Hall measurement and electronic devices.

Electrochemical Detection of Clenbuterol in Pig Liver at Pyrrole DNA Modified Boron-doped Diamond Electrode

The direct detection of clenbuterol（CL） in pig liver without any extraction separation at a pyrrole-DNA modified boron-doped diamond（BDD） electrode is reported. The pyrrole-DNA modified BDD electrode has a strong electrocatalytic effect on the redox reaction of CL. One oxidization and two reduction peaks of CL appear at 340. 2, 299. 8 and 166. 6 mV（ versus SCE）, respectively. The pyrrole polymer alone cannot electrocatalyze the above reaction at a BDD electrode ; the electrocatalytic effect of a BDD electrode modified with DNA membrane is unsufficient for the analytical detection of CL; the replacement of boron-doped diamond by glass carbon makes the electrocatalytic reaction impossible ; the redox process is pH dependent. The influences of various experimental parameters on the pyrrole-DNA modified BDD electrode were investigated. A sensitive cyclic vohammetric response for CL was obtained in a linear range from 3.4 × 10^-6 to 5 × 10^ -4 mol/L with a detection limit of 8.5 × 10^-7 mol/L. A mean recovery of 102. 7% of CL in the pig liver sample solution and a reproducibility of 3.2% were obtained.

Electroanalytical Investigation on Paracetamol on Boron-Doped Diamond Electrode by Voltammetry

An electroanalytical method was developed for the direct quantitative determination of paracetamol in tablets based on its oxidation behavior. The electrochemical oxidation and determination of paracetamol were easily carried out on born-doped diamond (BDD) electrode using two voltammetric techniques (CV and DPV). The electrochemical measurements performed by cyclic voltammetric (CV) and differential pulse voltammetry (DPV) techniques were carried out using a cathodically pretreated boron-doped diamond electrode in HClO4 and KClO4 electrolytes. HClO4 was then selected for analytical purposes and scan rate studies were also completed. The oxidation of the paracetamol is found to be irreversible and a diffusion-controlled nature of the paracetamol oxidation peak was established. A linear calibration curve for DPV analysis was constructed in the paracetamol concentration range from 0 μM to 13.87 μM, with 0.16 μM and 0.55 μM as the detection and quantification limit respectively.

Analytical Determination of Benzophenone-3 in Sunscreen Preparations Using Boron-Doped Diamond Electrodes

A new electroanalytical procedure was developed for the determination of Benzophenone-3 (BENZO) in commercial sunscreen as the active ingredient. The procedure is based on the use of electrochemical methods as cyclic and square-wave voltammetry, with boron-doped diamond (BDD) electrodes. The reduction of BENZO in Britton-Robinson buffer (0.1 mol●L–1) using this type of electrode gives rise to one irreversible peak in –1.30 V (versus Ag/AgCl) in presence of cationic surfactant cetyltrimethylammonium bromide (CTABr). The proposed electrochemical method was successfully applied to the analysis of commercially available pharmaceutical preparations.

White electroluminescence of n-ZnO:Al/p-diamond heterostructure devices

An n-ZnO：A1/p-boron-doped diamond heterostructure electroluminescent device is produced, and a rectifying be- havior can be observed. The electroluminescence spectrum at room temperature exhibits two visible bands centred at 450 nm-485 nm （blue emission） and 570 nm-640 nm （yellow emission）. Light emission with a luminance of 15 cd/m2 is observed from the electroluminescent device at a forward applied voltage of 85 V, which is distinguished from white light by the naked eye.

Schottky photodiode using submicron thick diamond epilayer for flame sensing

The sensing of a flame can be performed by using wide-bandgap semiconductors, which offer a high signal-to-noise ratio since they only response the ultraviolet emission in the flame. Diamond is a robust semiconductor with a wide-bandgap of 5.5 e V, exhibiting an intrinsic solar-blindness for deep-ultraviolet(DUV) detection. In this work, by using a submicron thick boron-doped diamond epilayer grown on a type-Ib diamond substrate, a Schottky photodiode device structure- based flame sensor is demonstrated. The photodiode exhibits extremely low dark current in both forward and reverse modes due to the holes depletion in the epilayer. The photodiode has a photoconductivity gain larger than 100 and a threshold wavelength of 330 nm in the forward bias mode. CO and OH emission bands with wavelengths shorter than 330 nm in a flame light are detected at a forward voltage of-10 V. An alcohol lamp flame in the distance of 250 mm is directly detected without a focusing lens of flame light.

Determination of band alignment between GaO_(x)and boron doped diamond for a selective-area-doped termination structure

An n-GaO_(x)thin film is deposited on a single-crystal boron-doped diamond by RF magnetron sputtering to form the pn heterojunction.The n-Ga Ox thin film presents a small surface roughness and a large optical band gap of 4.85 e V.In addition,the band alignment is measured using x-ray photoelectron spectroscopy to evaluate the heterojunction properties.The GaO_(x)/diamond heterojunction shows a type-Ⅱstaggered band configuration,where the valence and conduction band offsets are 1.28 e V and 1.93 e V,respectively.These results confirm the feasibility of the use of n-GaO_(x)as a termination structure for diamond power devices.

Direct and Simultaneous Determination of Phenol, Hydroquinone and Nitrophenol at Boron-Doped Diamond Film Electrode

The electrochemical characteristics of multi-component phenolic pollutants, such as phenol （Ph）, hydroquinone （HQ） and 4-nitrophenol （4-NP）, were investigated on boron-doped diamond （BDD） film electrode by differential pulse voltammetry （DPV） technique. A simple and feasible platform was accordingly established for the direct and simultaneous determination of these three phenolic pollutants. Results showed that, Ph, HQ and 4-NP gave obvious oxidation peaks on BDD electrode at the potential of 1.24, 0.76 and 1.52 V, respectively. Each of them displayed good linear relationship between their oxidation peak currents and their corresponding concentrations in a rather wide range coexisting with one or two of the other phenolic pollutants. The detection limits of Ph, HQ and 4-NP were estimated to be as low as 1.82×10^-6, 1.67×10^-6 and 1.44×10^-6 mol·L^-1, respectively. Therefore, a promising direct and simultaneous electrochemical determination method of multi-component phenolic pollutants in wastewater samples was constructed successfully on BDD electrode with advantages being rapid, simple, convenient, sensitive, in situ and inexpensive.

Electrochemical reduction of CO_2 and degradation of KHP on boron-doped diamond electrodes in a simultaneous and enhanced process

In this research a novel electrochemical system using dual boron-doped diamond (BDD) electrodes as the anode and cathode, for the first time, has been developed for CO_2 conversion and wastewater treatment in a synergetic and simultaneous process. On the BDD cathode CO_2 is converted into formaldehyde while in the anodic side organic wastes are decomposed on the BDD anode. Interestingly, when potassium hydrogen phthalate (KHP) was used as the organic model to be degraded in the anodic side, a higher efficiency of formaldehyde generation from CO_2 was observed on the BDD cathode. The enhanced effect of formaldehyde formation in the presence of KHP oxidation suggests that this novel electrochemical system can combine conversion of CO_2 to the form of high-value chemicals and wastewater purification in a simultaneous and harmonious process.

Integration of 3D interconnected porous microstructure and high electrochemical property for boron-doped diamond by facile strategy

Three-dimensional(3D)porous boron-doped diamond(BDD)flm is an attractive electrode material but tough to synthesize.Herein,the 3D porous BDD flms were constructed in a facile and template-free way.The BDD/non-diamond carbon(NDC)composite flms were frstly fabricated by hot flament chemical vapor deposition(HFCVD)technique,and then the porous BDD flms with 3D interconnected porous microstructure,different pore size and NDC-free diamond were achieved by selective removal of NDC.It is manifested that higher electrochemical response,large double layer capacitance(17.54 m F/cm^(2))in diamond electrodes,wide electrochemical window of 2.6 V and superior long-term stability were achieved for 3D porous BDD flm.This derives from the synergistic effect of microstructure and phase composition of the porous flms.3D interconnected structure possesses prominent improvement of effective surface area and accessible porous channel,signifcantly enhancing the species adsorption and mass transfer.The3D porous BDD flms,composed of NDC-free diamond,exhibit excellent structural stability and corrosion resistance,which favor the enhancement of long-term stability and water splitting overpotential.The facile fabricating approach and excellent structure/electrochemical character demonstrate the appealing application in many electrochemical felds for 3D porous BDD flms,such as energy storage and conversion,wastewater treatment and purifcation.

Effect of oxygen terminated surface of boron-doped diamond thin-film electrode on seawater salinity sensing

Tremendous demands for highly sensitive and stable seawater salinometers have motivated intensive research on advanced electrode materials.Boron-doped diamond(BDD)is attractive in terms of its high mechanical stability and chemical inertness,but is usually hindered by its low double-layer capacitance(C_(dl))for seawater salinity detection.Here,inspired by the principle of oxygen-terminated BDD electrode endowing higher C_(dl)than hydrogen-terminated surface,we introduce the oxygen terminated surface by oxygen plasma or reactive ion etch(RIE),and the fabricated oxygen terminated BDD electrodes demonstrate high sensitivity and long-term stability in seawater salinity detection comparing with the hydrogen terminated BDD electrodes.Significantly,the as-fabricated O-BDD-RIE electrodes not only show remarkable enhanced response even better than the commercial platinum black electrodes but also display long-time stability which is weekly verified by continuous monitor for 90 days.The outstanding performance of the oxygen terminated BDD electrodes can be ascribed to the enhancement of C-O surface functional group on C_(dl).In addition,a comprehensive analysis of effective electroactive surface area(EASA)and C_(dl)proves that the surface oxygen is the major factor for the improved C_(dl).In summary,the excellent oxygen terminated BDD electrodes promise potential application in seawater salinity detection.

The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes

In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond（BDD） anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in Na Cl;however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and Na Cl O4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine（Cl2, HCl O, Cl O-）electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density（≤ 10 m A/cm2） and neutral medium（p H in the range 6–9） should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate.

有机废水电化学氧化阳极材料的研究进展

阳极材料是电化学氧化法处理有机废水的关键。综述了贵金属电极、碳素电极、钛基金属氧化物电极和合成掺硼金刚石(BDD)薄层电极在内的常用阳极材料的性能,并对有机废水电化学氧化阳极材料的发展趋向进行了展望。

金刚石膜电极电化学氧化提高废水可生化性的研究

采用掺硼金刚石膜电极(BDD)电化学氧化的方法提高2-氯苯酚废水的可生化性,与钛基钌铱氧化物电极(DSA)进行对比,研究了该方法的机理.结果表明,BDD电极电化学氧化2.0h后,BOD5/CODCr值达到0.42,有效提高了废水的可生化性,而DSA电极电化学氧化2.0h后,BOD5/CODCr值仅为0.24.机理研究表明,由于BDD电极具有高的析氧电位,可产生大量的羟基自由基(·OH),能够使2-氯苯酚的苯环充分开环,形成草酸、顺丁烯二酸等易生化处理的中间产物,从而使可生化性提高;而DSA电极的析氧电位较低,产生羟基自由基的能力较差,不能有效地提高废水的可生化性.

锌、镉、铅离子在原位铋修饰掺硼金刚石薄膜电极上的传感分析

以原位铋修饰掺硼金刚石薄膜电极为传感电极,利用阳极溶出伏安法对重金属离子Zn^(2+)、Cd^(2+)、Pb^(2+)进行同时检测分析。原位铋修饰掺硼金刚石薄膜电极可有效提高Zn^(2+)、Cd^(2+)、Pb^(2+)的溶出峰值电流。考察了p H值、扫描方式、电极硼掺杂浓度、富集电位等参数对检测分析的影响。在优化的实验条件下,原位铋修饰BDD电极对Zn^(2+)、Cd^(2+)、Pb^(2+)传感分析具有良好的特性,在10~300μg/L浓度范围内具有良好的线性度和重复性,检出限分别为0.56、0.32和0.75μg/L(S/N=3)。干扰实验结果表明,3种重金属的相互干扰较小,除Cu^(2+)外,水中常见离子对测定干扰较小。实际水样中,3种离子的回收率为92.0%~114.0%。