Highly Sunlight Reflective and Infrared Semi-Transparent Nanomesh Textiles.

Radiative cooling in textiles is one of the important factors enabling cooling of the human body for thermal comfort. In particular, under an intense sunlight environment such as that experienced with outdoor exercise and sports activities, high near-infrared (NIR) reflectance to block sunlight energy influx along with high IR transmittance in textiles for substantial thermal emission from the human body would be highly desirable. This investigation demonstrates that a nanoscale geometric control of textile structure alone, instead of complicated introduction of specialty polymer materials and composites, can enable such desirable NIR and IR optical properties in textiles. A diameter-dependent Mie scattering event in fibers and associated optical and thermal behavior were simulated in relation to a nonwoven, nanomesh textile. As an example, a nanomesh structure made of PVDF (polyvinylidene fluoride) electrospun fibers with ∼600 nm average diameter was examined, which exhibited a significant radiative cooling performance with over 90% solar and NIR reflectance to profoundly block the sunlight energy influx as well as ∼50% IR transmittance for human body radiative heat dissipation. An extraordinary cooling effect, as much as 12 °C, was obtained on a simulated skin compared to the normal textile fabric materials. Such a powerful radiative cooling performance together with IR transmitting capability by the nanomesh textile offers a way to efficiently manage sunlight radiation energy to make persons, devices, and transport vehicles cooler and help to save energy in an outdoor sunlight environment as well as indoor conditions.

Synthesis and Characteristic Properties of Crosslinked Chitosan with Epichlorohydrin for Nitrate Removal from Water.

In this study, we prepared chitosan beads cross-linked with epichlorohydrin (CB-ECH) to improve the removal of nitrate in groundwater. It was confirmed that CB-ECH exhibited higher thermal stability and well-developed nano-pores compared to the pure chitosan beads (CB) by the thermogravimetric analyzer, nitrogen gas adsorption and desorption isotherm, and field emission scanning microscopy analysis. The CB-ECH showed a higher nitrate adsorption amount than the pure CB. Nitrate adsorption behaviors of CB-ECH were further investigated using adsorption isotherm, adsorption kinetics, adsorption energy distribution, and Gibbs free energy distribution models. The adsorption equilibrium and kinetics of nitrate ion on CB-ECH were well explained by the Sips isotherm and homogeneous surface diffusion model, respectively. It was also found from the AED analysis that the CB-ECH represent the heterogeneous adsorption behaviors for nitrate.

Preparation of Mesoporous Gamma Alumina Derived from Waste Can for Nutrient Recovery Process.

Mesoporous gamma alumina (MGA) was synthesized using aluminum trash containers by a low temperature hydrothermal method for effectively removing phosphate from wastewater. The effects of precursor concentrations in gel precipitation process over the pore size and surface area of MGA were investigated in detail. The phosphate removal by prepared MGAs were rigorously investigated through adsorption isotherms and kinetics of phosphate.

Synthesis of Walnut Shaped V2O3 Particles and Its Photocatalytic Activity for Methylene Blue Degradation Under Visible Light Irradiation.

In this study, walnut-shaped V2O3 particles with high photocatalytic activity in the visible light were synthesized by hydrothermal process. The V2O3 samples synthesized with the various temperature conditions of the hydrothermal process were characterized using XRD, SEM, TEM, UV-Visible spectrometer and N2gas adsorption/desorption analysis. For investigating the photocatalytic performance of synthesized V2O3 particles in the visible light condition, photodegradation experiments of methylene blue (MB) solution under artificial sunlight irradiation was conducted. As a result, the V2O3 hydrothermal-synthesized at 280 °C was composed of pure V2O3 crystal structure and showed high photocatalytic activity for the degradation of MB dye in visible light.

Radio-Frequency Thermal Plasma Treated Activated Carbon Impregnated with Mn and Ag for Volatile Organic Compounds Adsorption.

In this study, we have prepared a composite adsorbent with highly dispersed Mn and Ag nanocatalyst on the surface of activated carbon (AC) by applying the Radio-Frequency (RF) thermal plasma technique for the efficient removal of VOCs. The ACs before and after metal impregnation with RF plasma treatment were characterized by SEM, TEM, EDS, and nitrogen adsorption analysis. Adsorption behaviors of toluene, acetaldehyde, and formaldehyde on ACs before and after modification were also investigated in fixed-bed systems. The experimental adsorption results for VOCs on parent ACs and metal impregnated ACs (Mn-AC and Mn/Ag-AC) were well explained by modified continuous sigmoidal (MCS) model.

Synthesis of zeolitic material from basalt rock and its adsorption properties for carbon dioxide.

A zeolitic 4A type material was successfully prepared from natural basalt rock by applying an alkali fusion process and hydrothermal synthesis. In particular, the optimum synthetic conditions were examined at different crystallization times. Several methods such as XRD, SEM, EDX, and N2 and CO2 adsorption analysis were used to characterize the synthesized 4A type zeolite. In addition, CO2 adsorption equilibrium capacities for this basalt base zeolite were measured over temperature ranges from 283 to 303 K and pressure ranges from 0.1 to 1500 kPa in a volumetric adsorption apparatus. Then the results were compared to those of commercial zeolite. Moreover, to further investigate the surface energetic heterogeneity of the prepared zeolite, the isosteric heat of adsorption and adsorption energy distribution was determined. We found that basalt based zeolite 4A shows a CO2 adsorption equilibrium capacity of 5.9 mmol g-1 (at 293 K and 1500 kPa) which is much higher than the 3.6 mmol g-1 of the commercial zeolite as its micro-pore surface area, micro-pore volume and surface heterogeneity indicate.

Correction: Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells.

Correction for 'Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells' by Kyung-Jun Hwang et al., Phys. Chem. Chem. Phys., 2015, 17, 21974-21981.

Synthesis of ZnS Microspheres by Template-Free Hydrothermal Method for Photocatalytic Reaction.

In this work, ZnS microspheres consisting of nanoblocks were synthesized by a simple, template-free approach employing a hydrothermal reaction at different temperatures, using Zn(CH3COO)2 and Na2S2O3 · 5H2O as starting materials in the aqueous solution. The synthesized samples were characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET). The photocatalysts were evaluated using photodecomposition of methylene blue under UV-C light. The photocatalytic degradation rate followed a pseudo-first-order equation. The kinetic constant (k1) of the ZnS microspheres was 5.43 x 10(-2) min(-1).

Influence of Glyoxal on Preparation of Poly(Vinyl Alcohol)/Poly(Acrylic Acid) Blend Film.

The preparation of a poly(vinyl alcohol)/poly(acrylic acid)/glyoxal film (PVA = poly(vinyl alcohol); PAA = poly(acrylic acid)) with high tensile strength and hydrophobic properties by using the crosslinking reaction for OH group removal is reported herein. PAA was selected as a crosslinking agent because the functional carboxyl group in each monomer unit facilitates reaction with PVA. The OH groups on unreacted PVA were removed by the addition of glyoxal to the PVA/PAA solution. The chemical properties of the PVA/PAA films were investigated using Fourier transformation infrared spectroscopy and the thermal properties of the PVA/PAA/glyoxal films were investigated by means of differential scanning calorimetry and thermogravimetric analysis. A tensile strength of 48.6 N/mm2 was achieved at a PVA/PAA ratio of 85/15 for the PVA/PAA film. The tensile strength of the cross-linked PVA/PAA/glyoxal film (10 wt% glyoxal) was increased by 55% relative to the pure PVA/PAA (85/15) film. The degree of swelling (DS) and solubility (S) of the 10 wt% (PVA/PAA = 85/15, wt%) film added 10 wt% glyoxal were 1.54 and 0.6, respectively.

Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells.

The adsorption mechanism for the N719 dye on a TiO2 electrode was examined by the kinetic and diffusion models (pseudo-first order, pseudo-second order, and intra-particle diffusion models). Among these methods, the observed adsorption kinetics are well-described using the pseudo-second order model. Moreover, the film diffusion process was the main controlling step of adsorption, which was analysed using a diffusion-based model. The photodynamic properties in dye-sensitized solar cells (DSSCs) were investigated using time-resolved transient absorption techniques. The photodynamics of the oxidized N719 species were shown to be dependent on the adsorption time, and also the adsorbed concentration of N719. The photovoltaic parameters (Jsc, Voc, FF and η) of this DSSC were determined in terms of the dye adsorption amounts. The solar cell performance correlates significantly with charge recombination and dye regeneration dynamics, which are also affected by the dye adsorption amounts. Therefore, the photovoltaic performance of this DSSC can be interpreted in terms of the adsorption kinetics and the photodynamics of oxidized N719.

Influence of TiO2 nanofiber additives for high efficient dye-sensitized solar cells.

TiO2 nanofibers were prepared from a mixture of titanium-tetra-isopropoxide and poly vinyl pyrrolidone by applying the electrospinning method. The samples were characterized by XRD, FE-SEM, TEM and BET analyses. The diameter of electrospun TiO2 nanofibers is in the range of 70 approximately 160 nm. To improve the short-circuit photocurrent, we added the TiO2 nanofibers in the TiO2 electrode of dye-sensitized solar cells (DSSCs). TiO2 nanofibers added in DSSCs can make up to 20% more conversion energy than the conventional DSSC with only TiO2 films only.

Photovoltaic performance of nanoporous TiO2 replicas synthesized from mesoporous materials for dye-sensitized solar cells.

For dye-sensitized solar cell (DSSC), highly ordered nanoporous TiO2 materials with crystalline frameworks were successfully synthesized from different silica templates including SBA-15, KIT-6 and MSU-H. A photoelectrode in DSSC was fabricated by adsorbing cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)bis-tetrabutylammonium dye (N719) onto the prepared TiO2 nanoparticles. The samples were characterized by XRD, TEM, FE-SEM, AFM and Brunauer-Emmett-Teller (BET), and FT-IR analysis. An investigation of the influence of the bonding structure of N719 dye and nanoporous TiO2 on the photovoltaic performance of DSSC revealed that the bonding structure of N719 on TiO2 films is caused by the unidentate and bidentate linkage. Based on the overall conversion efficiency (eta), fill factor (FF), open-circuit voltage (V(oc)) and short-circuit current (/sc) from the I-V curves measured, it was observed that the photoelectric performance is strongly dependent on the dispersion properties of the nanoporous TiO2 replicas from mesoporous silica templates.

Hydrochloric acid treatment of TiO2 electrode for quasi-solid-state dye-sensitized solar cells.

Quasi-solid-state dye-sensitized solar cell was fabricated by sandwiched polymer electrolyte containing liquid electrolytes between the dye-sensitized TiO2 electrode and a Pt electrode. The influence of hydrochloric acid treatment of TiO2 photoelectrode on the photoelectronic performance was investigated. Quasi-solid-state dye-sensitized solar cell showed better photoelectronic performance when the TiO2 electrode was treated with hydrochloric acid than that without treatment. The short-circuit current density (J(sc)), the open-circuit voltage (V(oc)), and a conversion efficiency obtained for an incident light intensity of 100 mW m(-2) were 6.49 mA cm(-2), 0.76 V and 4.1%, respectively. It was found that the hydrochloric acid treatment of TiO2 electrode increased the short-circuit current density and cell efficiency.

Photocurrent-voltage of a dye-sensitized nanocrystalline TiO2 solar cells influenced by N719 dye adsorption properties.

Titanium particles of single-phase anatase nanocrystallites were prepared by the hydrolysis of titanium tetraisopropoxide. A dye-sensitized solar cell (DSSC) was fabricated by adsorbing cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)bis-tetrabutylammonium dye (N719) onto TiO2 film. The samples were characterized by XRD, TEM, FE-SEM, AFM, and Brunauer-Emmett-Teller (BET) analysis. The influence of the acetic acid treatment of TiO2 electrode with different concentrations on the photovoltaic performance of DSSC was investigated. It was found that DSSC had better photoelectric performance when the TiO2 electrode was treated by acetic acid of 0.5 M. An equivalent circuit analysis using the one-diode model was used to evaluate the influences of adsorption quantity and acetic acid treatment on the energy conversion efficiency of DSSC. A nonlinear least-square optimization method was used to determine five model parameters.