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A composite film with switchable transparency is fabricated by sandwiching a carbon nanotube (CNT) sheet within polyurethane (PU) films. The introduction of CNTs not only makes the composite film electrically conductive but also induces a rapid crystal melting of soft segments in the PU. As a result, the film can be switched from opaque to transparent in just several seconds after turning on voltage, and reversed back to opaque after turning off voltage. The film also possesses several other attractive properties, including excellent flexibility, low energy consumption, switching speed insensitivity to ambient temperature, and easy coloration, which make the film promising for a wide variety of practical applications.

The direct electrochemistry of hemoglobin (Hb) immobilized on a hexagonal mesoporous silica (HMS)-modified glassy carbon electrode was described. The interaction between Hb and the HMS was investigated using UV-Vis spectroscopy, FT-IR, and electrochemical methods. The direct electron transfer of the immobilized Hb exhibited two couples of redox peaks with the formal potentials of -0.037 and -0.232 V in 0.1 M (pH 7.0) PBS, respectively, which corresponded to its two immobilized states. The electrode reactions showed a surface-controlled process with a single proton transfer at the scan rate range from 20 to 200 mV/s. The immobilized Hb retained its biological activity well and displayed an excellent response to the reduction of both hydrogen peroxide (H2O2) and nitrate (NO2-). Its apparent Michaelis-Menten constants for H2O2 and NO2- were 12.3 and 49.3 microM, respectively, showing a good affinity. Based on the immobilization of Hb on the HMS and its direct electrochemistry, two novel biosensors for H2O2 and NO2- were presented. Under optimal conditions, the sensors could be used for the determination of H2O2 ranging from 0.4 to 6.0 microM and NO2- ranging from 0.2 to 3.8 microM. The detection limits were 1.86 x 10(-9) M and 6.11 x 10(-7) M at 3sigma, respectively. HMS provided a good matrix for protein immobilization and biosensor preparation.

Abstract: Carbon nanotube (CNT)/α-Ni(OH)2 composite paper based on CNT paper was prepared by a facile chemical bath deposition (CBD) method. α-Ni(OH)2 nanosheets were vertically grown on individual CNTs in CNT paper to form hierarchical nanowires. The loading mass of α-Ni(OH)2 in the composite paper could be 66wt%. Thus the composite paper showed much higher specific surface area than that of pristine CNT paper. This novel structure brings the composite paper an electrochemical capacitance high to 1144F/g at the current density of 0.5A/g, and maintains 585F/g at 10A/g. This composite paper could be a promising candidate for the electrodes of high-performance supercapacitors. [Copyright &y& Elsevier]

In this paper, three-dimensional ordered macroporous platinum catalysts with high real surface area were synthesized using the inverted colloidal crystals template technique and have been employed for the electrooxidation of methanol. The morphology and electrocatalytic behavior of the porous Pt electrodes were investigated with atomic force microscopy and electrochemical techniques. For the same amount of Pt deposited, the real surface areas of the electrodes are 9.16 and 8.00 cm² for the porous electrodes with pore size of 320 and 500 nm respectively, which are more than 5 times larger than the directly deposited Pt electrode (1.4 cm²). The pore size effect on the methanol electrooxidation was investigated by testing low concentration solution of methanol and porous materials with different pore sizes. The synthesized macroporous Pt electrode shows high stability toward the electrooxidation of methanol and is promising for the direct methanol fuel cell. [ABSTRACT FROM AUTHOR]

Active carbon nanofibers (CNFs) with porous structure show highly electrochemical double-layer capacitance for supercapacitors because of their large specific area. However, their poor crystallization induced the low conductivity, which could largely limit the electrochemical performance of the porous CNFs. In this research, porous CNFs with single-walled carbon nanotubes (SWCNTs) were prepared by electrospinning and high temperature carbonization. The introduction of SWCNTs into porous CNFs could largely enhance the conductivity of the porous CNF nanotextiles, thus the electrochemical performance of the composite nanotextile was largely enhanced. The specific capacitance of the composite could achieve 417 F/g at a current density of 0.5 A/g, and keep 193 F/g at the high current density of 10 A/g. Furthermore its specific capacitance could keep 96% after 2000 cycles of charge/discharge at the current density of 10 A/g. This nanotextile could be a promising candidate for the binder-free and filler-free electrodes of high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

A toluidine blue O (TBO) terminated self-assembled monolayer (SAM-I) was fabricated on a gold disk electrode by nucleophilic attack of the amino group in the reduced TBO on an immobilized carbonyl moiety of terephthaloyl chloride with cyclic scanning. The TBO units in the SAM-I were observed by surface enhanced Raman spectroscopy (SERS). The average TBO surface coverage of SAM-I was (2.5±0.5)×10−10 mol cm−2. Meanwhile, another TBO derived SAM (SAM-II) was prepared for comparison by activating the free carboxyl group of bound terephthaloyl chloride and then reacting it with the amino group of TBO. The average TBO surface coverage of SAM-II was only (6.8±0.1)×10−11 mol cm−2. Both SAMs possessed good electroactivity and showed identical properties. With an electrooxidative coupling of TBO units in SAM-I, a novel electroactive polymerized TBO monolayer (Film-I) was constructed, which displayed an improved stability and obvious electrochemical blocking effect. As a comparison, a poly(TBO) film (Film-II) was obtained by the electrochemical polymerization of TBO in solution on SAM-I for remedying the defectiveness of the knitted structure of Film-I. The SERS displayed more TBO units in Film-II than in Film-I. Film-II provided a much better barrier to the redox probe of K3[Fe(CN)6] due to the formation of the perfect structure. [Copyright &y& Elsevier]