Phenol degradation by anodic oxidation on boron-doped diamond electrode combining TiO_2 Photocatalysis

Boron-doped diamond （BDD） electrocatalysis is combined with photocatalysis using titanium dioxide （TiO2） as a catalyst to improve pollutant-oxidation efficiency. Phenol solution is chosen as model wastewater. Different methods involving BDD and/or TiO2 during the degradation processes are compared. Parameters such as the currency density and initial concentration are varied in order to determine their effects on the oxidation process. Moreover, the degradation kinetics of phenol is experimentally studied. The results reveal the superiority of series combination of BDD and TiO2, especially the treatment process of electrocatalysis and succedent photocatalysis, and the optimum working currency density for electrocatalysis is 25.48 mA/cm2. The removal rate decreases with the increase in the initial phenol concentration and the degradation reaction follows quasi-first-order kinetics equation.

Boron-Doped Diamond-Film-Based Two-Dimensional Electrode of Electrophoresis Tank

Chemically robust conductive p-type boron-doped diamond （BDD） films are an important electrode material and have been widely applied in electrochemistry. In this study, BDD films are taken as a two-dimensional （2D） electrode in a eleetrophoresis tank system instead of the conventional one-dimensional platinum wire electrode. The theoretical simulations by finite element numerical analysis reveal that the 2D BDD electrodes have relatively high intensity and uniformity of electric field in the tank. Experimentally, the 2D BDD electrodes with smaller size show excellent properties for the separation of DNA fragments. The advantages of the 2D BDD electrodes with chemical inertness, sustainability, high intensity and uniformity electronic field, as well as reduced small size of electrophoresis tank would open a possibility for realizing new generation, high-performance biological 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.

Electrolytic Production of NF3 Using Boron-Doped Diamond Anode in Molten NH4F·2HF

The current efficiency for NF3 formation was independent on the current density in the range of 200 to 1,000 mA·cm^2. The average values of NF3 current efficiencies on the BDD （boron-doped diamond） anode with the boron-concentration of 2,500 ppm were 32.3% at 80℃, 63.3% at 100℃ and 59.7% at 120℃. The best current efficiencies for NF3 formation on the BDD anode with boron-concentrations of 2,500, 5,000 and 7,500 ppm were obtained at 100℃ and those were 63.3%, 73.3% and 56.2%, respectively. Although anode effect occurred on the BDD electrodes covered with a part of the surface of the spiculate structure, which had the boron-concentrations higher than 7,500 ppm, it did not take place on the BDD electrodes covered with the surface of diamond structure, even if the BDD electrode had the boron-concentration of 8,000 ppm.

BDD电极电催化降解苯酚废水的研究

采用直流等离子体化学气相沉积方法制备了硼掺杂金刚石(BDD)薄膜电极。以苯酚为目标污染物,研究了苯酚废水在电极上的电化学降解规律及降解历程。结果表明,不同浓度的苯酚在电极上均能够完全矿化成CO2。高浓度条件下,苯酚先转化成中间产物,然后中间产物再氧化成CO2;低浓度条件下,苯酚氧化反应迅速,直接矿化成CO2。提高电流密度能够加速苯酚的降解,但会导致电流效率下降。苯酚的降解历程为对位首先受到·OH自由基的攻击,生成对苯二酚,再开环形成顺、反丁烯二酸与乙酸,然后顺、反丁烯二酸在阴极还原为丁二酸,丁二酸氧化脱羧形成丙二酸、乙酸、草酸或甲酸,最终氧化成CO2。

An Electrochemical Cleaning Technique for Removal of Surface Contamination before Texturization of Silicon Solar Cells

In order to decrease the consumption of reagents and silicon during removal of surface contamination before silicon texturing in solar cell manufacturing industry, a new low-cost surface treatment approach of electrochemical cleaning technique(ECT) is reported. In this technique, a powerful oxidizing electrolyte was obtained from the electrochemical reaction on Boron-doped Diamond(BDD) electrodes, and applied during removal of surface contaminations on silicon wafer surfaces. The slightly polished monocrystalline silicon surfaces after cleaning were compared with the ones of primal silicon wafers. The measurement results show that ECT is quite efficient in removing NaCl and organic contaminants. After cleaning, the contrast test was conducted for the textured silicon wafers with/without pre-treatment(polish) separately. The results show that the size of pyramids on the surface without traditional polishing process is homogeneous and smaller than 4μm, and the average surface reflectance is much lower in the wavelength range from 400nm to 800nm. Therefore, the new technique can save silicon material, and effectively avoid optical losses for improving photoconversion effect of solar cells.