Heterojunction photoanode of SnO2 and Mo-doped BiVO4 for boosting photoelectrochemical performance and tetracycline hydrochloride degradation.

The photoelectrochemical (PEC) method has a potential to harvest solar energy for sustainable energy and degrade contaminants. Herein, we fabricated cauliflower-like SnO2 and porous Mo-doped BiVO4 (SnO2/Mo:BiVO4) photoelectrodes by a sol-gel spin-coating method for better PEC performance and higher degradability of tetracycline hydrochloride (TC-HCl). The SnO2 layer plays a crucial role in attaining a smooth and uniform surface of the photoanodes for blocking holes to defect trap sites and preventing charge recombination with improved light utilization. Mo dopants serve as nuclei for the crystallization of BiVO4 and for making charge-adjustable porous structures for PEC performance. Thus, the content-optimized SnO2/Mo:BiVO4 photoanode film presents the highest photocurrent density of 0.59 mA cm-2 at 1.23 VRHE of 82.1% TC-HCl decomposition efficiency within 120 min at a rate constant of 1.49 × 10-2 min-1, providing a promising method for green environmental applications.

All-solid-state flexible supercapacitors fabricated with bacterial nanocellulose papers, carbon nanotubes, and triblock-copolymer ion gels.

We demonstrate all-solid-state flexible supercapacitors with high physical flexibility, desirable electrochemical properties, and excellent mechanical integrity, which were realized by rationally exploiting unique properties of bacterial nanocellulose, carbon nanotubes, and ionic liquid based polymer gel electrolytes. This deliberate choice and design of main components led to excellent supercapacitor performance such as high tolerance against bending cycles and high capacitance retention over charge/discharge cycles. More specifically, the performance of our supercapacitors was highly retained through 200 bending cycles to a radius of 3 mm. In addition, the supercapacitors showed excellent cyclability with C(sp) (~20 mF/cm(2)) reduction of only <0.5% over 5000 charge/discharge cycles at the current density of 10 A/g. Our demonstration could be an important basis for material design and development of flexible supercapacitors.

Numerical analysis for the thermophoretic coagulation of monodisperse particles at continuum regime.

Coagulation is a process wherein aerosol particles collide with one another and adhere to form large particles in the system due to their relative motions. In this letter, we investigated thermophoretic coagulation of monodisperse aerosols on a constant temperature gradient between particles and gas molecules using a FDM (finite difference method) technique. The basic concept is to focus on a single particle attracting other particles considering their diffusional and thermophoretic motions to its collision surface. From the results of simulated particle flux, it shows that the thermophoretic coagulation is more effective for higher temperature gradient in the monodisperse aerosol particles.

Slip Correction Measurements of Certified PSL Nanoparticles Using a Nanometer Differential Mobility Analyzer (Nano-DMA) for Knudsen Number From 0.5 to 83.

The slip correction factor has been investigated at reduced pressures and high Knudsen number using polystyrene latex (PSL) particles. Nano-differential mobility analyzers (NDMA) were used in determining the slip correction factor by measuring the electrical mobility of 100.7 nm, 269 nm, and 19.90 nm particles as a function of pressure. The aerosol was generated via electrospray to avoid multiplets for the 19.90 nm particles and to reduce the contaminant residue on the particle surface. System pressure was varied down to 8.27 kPa, enabling slip correction measurements for Knudsen numbers as large as 83. A condensation particle counter was modified for low pressure application. The slip correction factor obtained for the three particle sizes is fitted well by the equation: C = 1 + Kn (α + ß exp(-γ/Kn)), with α = 1.165, ß = 0.483, and γ = 0.997. The first quantitative uncertainty analysis for slip correction measurements was carried out. The expanded relative uncertainty (95 % confidence interval) in measuring slip correction factor was about 2 % for the 100.7 nm SRM particles, about 3 % for the 19.90 nm PSL particles, and about 2.5 % for the 269 nm SRM particles. The major sources of uncertainty are the diameter of particles, the geometric constant associated with NDMA, and the voltage.

Polarized light scattering by dielectric and metallic spheres on oxidized silicon surfaces.

The polarization and intensity of light scattered by polystyrene latex and copper spheres with diameters of approximately 100 nm deposited onto silicon substrates containing various thicknesses of oxide films were measured with 532-nm light. The results are compared with a theory for scattering by a sphere on a surface, originally developed by others [Physica A 137, 209 (1986)] and extended to include coatings on the substrate. Nonlinear least-squares fits of the theory to the observations yield results that were consistent with differential mobility measurements of the particle diameter.

Polarized light scattering by dielectric and metallic spheres on silicon wafers.

The polarization and intensity of light scattered by monodisperse polystyrene latex and copper spheres, with diameters ranging from 92 to 218 nm, deposited on silicon substrates were measured with 442-, 532-, and 633-nm light. The results are compared with a theory for scattering by a sphere on a surface, originally developed by others [PhysicaA 137,209 (1986)], and extended to include coatings on the sphere and the substrate. The results show that accurate calculation of the scattering of light by a metal sphere requires that the near-field interaction between the sphere and its image be included in acomplete manner. The normal-incidence approximation does not suffice for this interaction, and the existence of any thin oxide layer on the substrate must be included in the calculation.