Yanzhu Lei

Fabrication and Electrochemical Treatment Application of A Novel Lead Dioxide Anode with Superhydrophobic Surfaces, High Oxygen Evolution Potential, and Oxidation Capability

A novel PbO(2) electrode with a high oxygen evolution potential (OEP) and excellent electrochemical oxidation performance is prepared to improve the traditional PbO(2) electrode, which is modified by changing the microstructure and wetting ability. A middle layer of TiO(2) nanotubes (NTs) with a large surface area is introduced on Ti substrate, and a small amount of Cu is predeposited at the bottom of TiO(2)-NTs. The modification will improve the electrochemical performance by enhancing the loading capacity of PbO(2) and the combination between PbO(2) and Ti substrate. The hydrophilic surface becomes highly hydrophobic by adding fluorine resin. The improved PbO(2) electrode exhibits a similar morphology, surface wetting ability, high OEP, and electrochemical performance with boron-doped diamond film (BDD) electrode. However, the physical resistance of the PbO(2) electrode is much lower than that of BDD, exhibiting higher conductivity. The hydroxyl radical utilization is significantly enhanced, resulting in a higher oxidation rate and higher removal for 2,4-dichlorophenoxyacetic acid.

Electrochemical degradation of chlorobenzene on boron-doped diamond and platinum electrodes

In this paper the electrochemical degradation of chlorobenzene (CB) was investigated on boron-doped diamond (BDD) and platinum (Pt) anodes, and the degradation kinetics on these two electrodes was compared. Compared with the total mineralization with a total organic carbon (TOC) removal of 85.2% in 6h on Pt electrode, the TOC removal reached 94.3% on BDD electrode under the same operate condition. Accordingly, the mineralization current efficiency (MCE) during the mineralization on BDD electrode was higher than that on the Pt electrode. Besides TOC, the conversion of CB, the productions and decay of intermediates were also monitored. Kinetic study indicated that the decay of CB on BDD and Pt electrodes were both pseudo-first-order reactions, and the reaction rate constant (k(s)) on BDD electrode was higher than that on Pt electrode. The different reaction mechanisms on the two electrodes were investigated by the variation of intermediates concentrations. Two different reaction pathways for the degradation of CB on BDD electrode and Pt electrode involving all these intermediates were proposed.

A simple, stable and picomole level lead sensor fabricated on DNA-based carbon hybridized TiO2 nanotube arrays.

An electrochemical lead sensor is developed on DNA-based vertically aligned conductive carbon hybridized TiO(2) nanotube arrays (DNA/C-TiO(2) NTs). The designed DNA/C-TiO(2) NTs sensor is superior in determination of lead with high sensitivity, selectivity and repeatability, as well as wide pH adaptability, fast electro-accumulation capacity for lead and easy regeneration. Such remarkable characteristics for lead sensing are attributed to the immobilization of abundant target biomolecules, DNA, and the enhanced bioelectrochemical activity. The controllable carbon hybridization of the TiO(2) NTs increases the conductivity of the electrode, while retaining the tubular structure, biocompatibility, and hydrophilicity. The results show that the lead sensor possesses a wide linear calibration ranging from 0.01 to 160 nM with the detection limitation at a picomole level (3.3 pM). The application of the present sensor is realized for determination of Pb(2+) in real water samples.

Highly efficient and mild electrochemical incineration: mechanism and kinetic process of refractory aromatic hydrocarbon pollutants on superhydrophobic PbO2 anode.

Aqueous aromatic hydrocarbons are chemically stable, high toxic refractory pollutants that can only be oxidized to phenols and quinone on either Pt or traditional PbO(2) electrodes. In this study, a novel method for the electrochemical incineration of benzene homologues on superhydrophobic PbO(2) electrode (hydrophobic-PbO(2)) was proposed under mild conditions. Hydrophobic-PbO(2) can achieve the complete mineralization of aromatic hydrocarbons and exhibit high removal effect, rapid oxidation rate, and low energy consumption. The kinetics of the electrochemical incineration was also investigated, and the results revealed that the cleavage of the benzene ring is a key factor affecting the incineration efficiency. Moreover, on hydrophobic-PbO(2), the decay of intermediates was rapid, and low concentrations of aromatics were accumulated during the reaction. The removal of the initial pollutants and the effects of oxidative cleavage were related to the number of methyl groups on the benzene ring. Specifically, the results of physical experiments and quantum calculations revealed that the charge density of carbon atoms increases with an increase in the number of methyl groups, which promotes the electrophilic attack of ·OH.

Ultrasound enhanced electrochemical oxidation of phenol and phthalic acid on boron-doped diamond electrode.

The enhancement on degradation of two typical organic pollutants, phenol (Ph) and phthalic acid (PA) on boron-doped diamond (BDD) electrode is particularly investigated in this study. Results show that ultrasound (US) has remarkable influence on electrochemical (EC) oxidation of the two pollutants including degradation efficiency, EC oxidation energy consumption, mass transport and electrochemical reaction. With US, the enhancement on degradation efficiency and decreasing of EC oxidation energy consumption of Ph are more obvious. US can also efficiently reduce the average electrochemical oxidation energy consumption (AE), decreasing by 74 and 69% for Ph and PA, respectively. Mass transport process can be greatly accelerated by US. The mass transport coefficients of Ph and PA both reach 2.0 x 10(-5)ms(-1) in ultrasound-assisted electrochemical (US-EC) process, from 5.4 x 10(-6) and 6.7 x 10(-6) ms(-1) in EC, increasing by 270 and 199%, respectively. The reaction amount of Ph decreases by 79% with US, from 6.49 x 10(-10) to 1.39 x 10(-10) mol cm(-2). For PA, the reaction amount decreases from 1.25x10(-11) to 3.11 x 10(-12) mol cm(-2) with US. The oxidation peak current increases by 32% for Ph. While for PA, there is no direct oxidation happened in US-EC process.

Fabrication of a novel atrazine biosensor and its subpart-per-trillion levels sensitive performance.

The present study describes an atrazine biosensor with the detection limit of 0.1 part-per-trillion (ppt). The atrazine biosensor is fabricated on tyrosinase-immobilized vertical growth TiO(2) nanotubes (Tyr/TiO(2)-NTs), based on the inhibition of tyrosinase by atrazine. The designed Tyr/TiO(2)-NTs present excellent applicability in atrazine determination, with high sensitivity and stability, and rapid response. The outstanding sensing characteristics for atrazine is attributed to the appropriate bioelectrochemical interface of Tyr/TiO(2)-NTs, resulting from the preponderant tubular structure, excellent biocompatibility, and hydrophilicity of TiO(2)-NTs. The atrazine biosensor possesses a wide detection range from 0.2 ppt to 2 part-per-billion (ppb). The practical application of the biosensor is realized for the determination of atrazine and the analysis of its transport in soil samples. A new method for determination of atrazine in soil samples is thus established, which greatly simplifies the preparation procedure of sample and is helpful to evaluate the pollution risk of atrazine to soil, groundwater, and surface water.

High Electrocatalytic Activity of Pt–Pd Binary Spherocrystals Chemically Assembled in Vertically Aligned TiO2 Nanotubes

To obtain noble metal catalysts with high efficiency, long-term stability, and poison resistance, Pt and Pd are assembled in highly ordered and vertically aligned TiO(2) nanotubes (NTs) by means of the pulsed-current deposition (PCD) method with assistance of ultrasonication (UC). Here, Pd serves as a dispersant which prevents agglomeration of Pt. Thus Pt-Pd binary catalysts are embed into TiO(2) NTs array under UC in sunken patterns of composite spherocrystals (Sps). Owing to this synthesis method and restriction by the NTs, the these catalysts show improved dispersion, more catalytically active sites, and higher surface area. This nanotubular metallic support material with good physical and chemical stability prevents catalyst loss and poisoning. Compared with monometallic Pt and Pd, the sunken-structured Pt-Pd spherocrystal catalyst exhibits better catalytic activity and poison resistance in electrocatalytic methanol oxidation because of its excellent dispersion. The catalytic current density is enhanced by about 15 and 310 times relative to monometallic Pt and Pd, respectively. The poison resistance of the Pt-Pd catalyst was 1.5 times higher than that of Pt and Pd, and they show high electrochemical stability with a stable current enduring for more than 2100 s. Thus, the TiO(2) NTs on a Ti substrate serve as an excellent support material for the loading and dispersion of noble metal catalysts.