An electroless-plating-like solution approach for the preparation of PS@TiO2@Ag core-shell spheres.

PS@TiO2@Ag spheres with triple-level core-shell nanostructures were prepared via a versatile coating procedure based on an electroless-plating-like solution deposition (EPLSD) method. A peroxo-titanium-complex (PTC) aqueous solution was used as the precursor to react with an aniline monomer in the EPLSD preparation. Aniline plays an important role in the TiO2 layer anchoring process through the swollen effects of the PS cores. As extended, peroxo-metal-complex (PMC) with the d0 configuration can be introduced onto PS spheres to form varieties of PS@metal oxide core-shell structures by this method under mild conditions. Ag layers were then modified onto the PS@TiO2 spheres via the photocatalytic method. By the extraction of the PS cores, hollow TiO2 and TiO2@Ag spheres could be obtained. The photochemical degradation of methylene blue (MB) under UV light irradiation was performed on the composite nanostructures.

A double-mediator based whole cell electrochemical biosensor for acute biotoxicity assessment of wastewater.

This work investigates the feasibility and sensitivity of a double-mediator based whole cell electrochemical biosensor to detect the acute biotoxicity of wastewater. The lipophilic mediator menadione was used to mediate the intracellular metabolic activities whereas hydrophilic potassium ferricyanide was employed as extracellular electron acceptor to transport the electron from the menadiol to anode. A chitosan hydrogel polymer film with boron-doped nanocrystalline diamond (BND) particles was electrodeposited onto a glassy carbon (GC) electrode to immobilize Saccharomyces cerevisiae cells and the mediators. The feasibility of the as-prepared biosensor was verified by determine the acute biotoxicity of four heavy metal ions(Cu2+, Cd2+, Ni2+, Pb2+), three phenol pollutants (3,5-dichlorophenol, 4-chlorophenol, phenol) and three real wastewater samples. The IC50 values for Cu2+, Cd2+, Ni2+, Pb2+ are 10.12mg/L,13.88mg/L, 17.06mg/L and 34.56mg/L. And the IC50 value is 16.48mg/L, 34.40mg/L and 44.55mg/L for 3,5-dichlorophenol, 4-chlorophenol and phenol, respectively. The results of this work indicate that the double-mediator based whole cell electrochemical biosensor could be applied into the acute toxicity assessment of real wastewater samples with excellent performance and highlight their merit as portable and sensitive, which may providing a reasonable and reliable way for wastewater toxicity online detection.

Correlation between band alignment and enhanced photocatalysis: a case study with anatase/TiO2(B) nanotube heterojunction.

It has long been known that efficient interfacial charge transfer between different phases of TiO2 is beneficial for enhanced photocatalysis. However, there has been considerable debate over the direction of the charge transfer across the interface of the different TiO2 phases. In this work, we study the case of TiO2 with a novel anatase/TiO2(B) heterojunction (ABHJ), wherein charge carrier transfer across the heterojunction interface is intensively investigated. The ABHJ is prepared by a two-step alkaline hydrothermal route and features nanotubes with a large surface area. Comprehensive analysis including UV-Vis-DRS, XPS, Mott-Schottky measurements, EPR and transient photovoltage techniques provides evidence for a type II band alignment in the ABHJ and migration of the photogenerated electrons from anatase to TiO2(B), which could effectively inhibit the recombination rate of photo-induced electron-hole pairs. Photocatalytic tests demonstrate that the as-obtained ABHJ shows higher activity than both the single phase and P25, not only for hydrogen production, but also for the photodegradation of gaseous acetaldehyde, which is due to the synergistic effect between an efficient charge separation at the interface and a high surface area.

Simple ethanol impregnation treatment can enhance photocatalytic activity of TiO2 nanoparticles under visible-light irradiation.

Doping with impurities as well as introducing oxygen vacancies has been recognized as an important means to enhance photocatalytic activity of TiO2 under visible-light irradiation. Here we report that simple ethanol impregnation followed with mild heat treatment (150-400 °C) can color TiO2 nanoparticles and enhance visible-light photocatalytic activity of the material. The coloration and photocatalytic activity for ß-naphthol and rhodamine B (RhB) degradation were observed to be dependent on heat-treatment temperature, and the highest activity as well as the most coloration was obtained at temperatures around 200 to 250 °C. Comprehensive analyses based on X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) investigations as well as first-principle density functional calculation suggest that the simple ethanol impregnation treatment leads to the generation of oxygen vacancy on TiO2 surface which should be responsible for the coloration and enhanced photocatalytic activity.

M\TiO2 (M=Au, Ag) transparent aqueous sols and its application on polymeric surface antibacterial post-treatment.

In this paper, we reported a simple and mild chemical method for synthesis of crystalline metal\TiO2 (M=Au, Ag) transparent aqueous sols at low temperature (80°C). It should be found that the as-synthesized metal\TiO2 sols could easily be coated on the flexible PET surfaces of the through the as-developed electroless-plating-like solution deposition (EPLSD) procedure. The as-prepared metal\TiO2 sols and related flexible thin film were characterized by TEM, SEM, XRD, UV-vis, and FTIR analysis. The results showed that the Au and Ag nanoparticles can significantly improve the optical absorption properties of TiO2 due to the surface plasmon generated by the noble metal, which in turn enhanced the photo-induced antibacterial performance of the as-prepared metal\TiO2 flexible film. Moreover, the photo-generated electrons could transfer between the metal and titanium dioxide under different irradiation (ultraviolet or visible light), which could significantly reduce the recombination of photo-induced electrons and holes, resulting in the better photo-induced antibacterial performance. Therefore, the EPLSD procedure may be used as a general polymeric surface antibacterial post-treatment procedure for preparing the metal\TiO2 flexible film because of the noble metal enhanced antibacterial performance.

Diamond nanowires: fabrication, structure, properties, and applications.

C(sp(3) )C-bonded diamond nanowires are wide band gap semiconductors that exhibit a combination of superior properties such as negative electron affinity, chemical inertness, high Young's modulus, the highest hardness, and room-temperature thermal conductivity. The creation of 1D diamond nanowires with their giant surface-to-volume ratio enhancements makes it possible to control and enhance the fundamental properties of diamond. Although theoretical comparisons with carbon nanotubes have shown that diamond nanowires are energetically and mechanically viable structures, reproducibly synthesizing the crystalline diamond nanowires has remained challenging. We present a comprehensive, up-to-date review of diamond nanowires, including a discussion of their synthesis along with their structures, properties, and applications.

Sorting of large-diameter semiconducting carbon nanotube and printed flexible driving circuit for organic light emitting diode (OLED).

A novel approach was developed to sort a large-diameter semiconducting single-walled carbon nanotube (sc-SWCNT) based on copolyfluorene derivative with high yield. High purity sc-SWCNTs inks were obtained by wrapping arc-discharge SWCNTs with poly[2,7-(9,9-dioctylfluorene)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole] (PFO-DBT) aided by sonication and centrifugation in tetrahydrofuran (THF). The sorted sc-SWCNT inks and nanosilver inks were used to print top-gated thin-film transistors (TFTs) on flexible substrates with an aerosol jet printer. The printed TFTs demonstrated low operating voltage, small hysteresis, high on-state current (up to 10(-3) A), high mobility and on-off ratio. An organic light emitting diode (OLED) driving circuit was constructed based on the printed TFTs, which exhibited high on-off ratio up to 10(4) and output current up to 3.5 × 10(-4) A at V(scan) = -4.5 V and Vdd = 0.8 V. A single OLED was switched on with the driving circuit, showing the potential as backplanes for active matrix OLED applications.

Large scale fabrication of highly monodispersed rattle-type TiO2@void@SiO2 spheres via synthesis-cum-organization process.

Architected nanostructures with interior space have attracted enormous attention due to both their esthetic beauty and their potential applications. It is a current dream to develop a template-free, one-pot and low-temperature synthetic routes for hetero-architecture in liquid media. In this manuscript, we develop a kind of template-free, low-temperature, and one-pot total synthetic strategy for synthesis of inorganic multi-component hetero-architecture. This synthetic strategy analogous to standard organic reactions used in total synthesis is an important breakthrough in inorganic chemical synthesis. We can achieve 1 kilogram (kg) yield of the TiO(2)@void@SiO(2) core-shell sphere one time by using this synthetic strategy, which may lead to practical applications of the sample. By embodying the new reaction and concept into future investigation, a more mature research field in synthetic architecture of nanomaterials can be anticipated.

2-Dimensional micro-network of boron-doped diamond film: fabrication and electrochemical sensing application.

By means of delicate and conventional methods based on photolithography and hot filament chemical vapor deposition (HFCVD) technology, a novel boron-doped diamond micro-network (BDDMN) film was fabricated, and this micro-structure showed excellent electrochemical sensing properties.

Low-temperature and one-step synthesis of rutile TiO2 aqueous sol by heterogeneous nucleation method.

A phase-pure rutile TiO(2) aqueous sol has been prepared by heterogeneous nucleation method with an aqueous peroxotitanate solution as a precursor and SnCl(2) as rutile-phase crystalline growth promoter at a temperature as low as 100 °C in one-step process. TEM, XRD and UV-Vis spectra were used to characterize the rutile TiO(2) sol. The results reveal that a pure rutile phase TiO(2) aqueous sol with average particle sizes of around 20 nm has been synthesized, and a transparent film of rutile TiO(2) was also easily prepared by dip-coating method. Formation conditions and a possible mechanism of phase-controlling were investigated. The results show that the presence of the Sn content is essential for the formation of a pure rutile TiO(2) phase at low temperature, which involves a heterogeneous nucleation mechanism.

Fabrication of boron-doped diamond nanorod forest electrodes and their application in nonenzymatic amperometric glucose biosensing.

A boron-doped diamond nanorod forest (BDDNF) electrode has been fabricated by hot filament chemical vapor deposition (HFCVD) method. This BDDNF electrode exhibits very attractive electrochemical performance compared to conventional planar boron-doped diamond (BDD) electrodes, notably improved sensitivity and selectivity for biomolecule detection. The BDDNF electrode, with the possibility of fabricating a sensitive biosensor for glucose without any catalyst or mediators, shows good activity toward direct detection of glucose by simply putting the bare BDDNF electrode into the glucose solution. Furthermore, the marked selectivity of the BDDNF electrode is very favorable for the determination of glucose in the presence of ascorbic acid (AA) and uric acid (UA). The robust sensitive and selective responses of this nanostructure indicate the promise of this kind of diamond electrode for real applications.

Non-enzymatic glucose detection using as-prepared boron-doped diamond thin-film electrodes.

Electrochemical oxidation of glucose in alkaline solution at as-prepared boron-doped microcrystalline diamond (BDMD) and nanocrystalline diamond (BDND) thin-film electrodes is investigated by cyclic voltammetry. The results demonstrate that glucose can be directly oxidized at as-prepared boron-doped diamond (BDD) thin-film electrodes and the curve of the negative scan traces onto the positive scan. The effect of sodium hydroxide concentration on the response of glucose is also studied in the range of 0.02-0.6 M and the optimum concentration of sodium hydroxide is found to be 0.1 M. The voltammetric signal of glucose and the mixture of ascorbic acid (AA) and uric acid (UA) can be observed well-separated at as-prepared BDD thin-film electrodes in 0.1 M sodium hydroxide solution. The peak current is proportional to the glucose concentration in the range 0.25-10 mM with a correlation coefficient of 0.9993 in the presence of AA and UA. Furthermore, the experiment results also show that the non-enzymatic glucose sensor based on as-prepared BDD thin-film electrodes has high sensitivity, good reproducibility and stability.