Conversion of Methanol to Para-Xylene over ZSM-5 Zeolites Modified by Zinc and Phosphorus.

In this work, the influence of different phosphorus sources and the modification of zinc and phosphorus on the performance of the conversion of methanol to aromatics (MTA) was investigated. The results showed that the phosphorus source had a significant impact on the selectivity of para-xylene (PX) in xylene and catalyst stability. The introduction of P resulted in the covering of the active acid sites and the narrowing of the pore of the ZSM-5 zeolite, which improved the shape-selectivity for PX in the methanol conversion reaction. Compared with the modifiers of H3PO4 and (NH4)3PO4, the ZSM-5 zeolite modified by (NH4)2HPO4 exhibited better catalyst stability and PX-selectivity due to its larger specific surface area, pore volume and suitable acidity. When the ZSM-5 zeolite was modified by Zn and P, the effect of Zn and P on the selectivity to aromatics and PX in xylene was almost opposite. With the increase in P-loading, the selectivity of PX in xylene gradually increased but at the cost of decreasing the aromatic-selectivity. On the other hand, the loading of Zn introduced Zn-Lewis acid sites to provide aromatization active centers and improved the aromatic-selectivity. However, excessive Zn reduced the selectivity of PX in xylene. The catalyst activity and aromatic-selectivity could be improved to some extent with an appropriate ratio of Zn and P, while maintaining or increasing the para-selectivity of xylene. Compared with 5% P/ZSM-5 catalyst modified with only (NH4)2HPO4, the PX selectivity in xylene over the Zn-P/ZSM-5 catalyst modified with 5% Zn and 1% P improved from 86.6% to 90.1%, and the PX yield increased by 59%.

Controllable Synthesis of ZnO Nanoparticles with Improved Photocatalytic Performance for the Degradation of Rhodamine B under Ultraviolet Light Irradiation.

In this work, two-dimensional (2D) Zn-HMT (Zn(NO3)2(HMT)2(H2O)2]n) nanosheets were synthesized using a facile one-step chemical precipitation in the presence of Zn(NO3)2, hexamine (HMT), and anhydrous ethanol at room temperature. Subsequently, hexagonal Tx-ZnO (Tx-ZnO refers to the zinc oxide (ZnO) nanoparticles) were synthesized by a high-temperature solid-phase method at different temperatures (x = 500, 550, 600, 650, 700, 750, and 800 °C) nanoparticles with different morphologies were synthesized by a high-temperature calcination approach using 2D Zn-HMT nanosheets as precursor. The crystal structure, morphology, specific surface areas, surface and interface properties, optical properties, and charge migration behaviors of the as-synthesized Tx-ZnO nanoparticles were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), automatic specific surface and aperture analyzer, X-ray photoelectron spectroscopy (XPS), UV-visible spectrophotometer, photoluminescence (PL) spectra, and electrochemical impedance spectroscopy (EIS). The photocatalytic performances and stabilities of the as-synthesized typical Tx-ZnO nanoparticles with various morphologies were evaluated and compared with the commercial ZnO (CM-ZnO) nanoparticle. The T700-ZnO nanoparticle with spherical and irregular morphology exhibited the highest photocatalytic activity (99.12%) for the degradation of Rhodamine B (RhB), compared to T500-ZnO (92.32%), T600-ZnO (90.65%), T800-ZnO (44.04%), and the CM-ZnO (88.38%) nanoparticle, which can be attributed to the cooperative effects of higher crystallinity, bigger crystal size, the strongest separation efficiency, the lowest recombination rate, the fastest charge carrier transfer path, and the highest charge-transfer efficiency. The superior photocatalytic activity illustrated by the T700-ZnO nanoparticle makes it have potential application prospects for the treatment of organic wastewater.

Facile Synthesis of Metal Oxide Decorated Carbonized Bamboo Fibers with Wideband Microwave Absorption.

Aiming at the disadvantages of high cost, complex processes, low yield, and narrow bandwidth of carbon-based microwave absorbing materials, this paper provides a novel and efficient method for synthesizing metal oxide/carbonized bamboo fibers using renewable natural bamboo fibers as a carbon source. The results suggested that the metal oxides such as NiO and Fe3O4 were uniformly dispersed on the carbonized bamboo fibers and proved that the dielectric component NiO and magnetic component Fe3O4 can significantly improve the microwave absorption performance of the carbonized bamboo fibers. As expected, the NiO/carbonized bamboo fibers showed excellent microwave absorption performance due to the appropriate complex permittivity, high impedance matching, and attenuation coefficient. A wide effective bandwidth of 6.4 GHz with 2.2 mm thickness is achieved, covering the entire Ku-band. Remarkably, the reflection loss (RL) values less than -10 dB covered the whole X-band at a thickness of 3.0 mm. This work reveals the potential of carbonized bamboo fibers-based composite as an economic and broadband microwave absorbent and offers a new strategy for designing promising microwave absorption materials.

Facile Synthesis of TiO2/MoS2 Composites with Co-Exposed High-Energy Facets for Enhanced Photocatalytic Performance.

In this work, with the the H2TiO3 colloidal suspension and MoS2 as the precursors, TiO2/MoS2 composites composed of anatase TiO2 nanocrystals with co-exposed {101} and [111]-facets (nanorod and nanocuboid), {101} and {010} facets (nanospindle), and MoS2 microspheres constructed by layer-by-layer self-assembly of nanosheets were hydrothermally synthesized under different pH conditions. The characterization has been performed by combining X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, and UV-visible absorption spectrum analyses. The photocatalytic degradation of rhodamine B (RhB) in an aqueous suspension was employed to evaluate the photocatalytic activity of the as-prepared pHx-TiO2/MoS2 composites. The photocatalytic degradation efficiency of pH3.5-TiO2/MoS2 composite was the highest (99.70%), which was 11.24, 2.98, 1.48, 1.21, 1.09, 1.03, 1.10, and 1.14 times that of Blank, MoS2, CM-TiO2, pH1.5-TiO2/MoS2, pH5.5-TiO2/MoS2, pH7.5-TiO2/MoS2, pH9.5-TiO2/MoS2, pH11.5-TiO2/MoS2, respectively. The pH3.5-TiO2/MoS2 composite exhibited the highest photocatalytic degradation rate, which may be attributed to the synergistic effects of its large specific surface area, suitable heterojunction structure, and favorable photogenerated charge-separation efficiency. This work is expect to provide primary insights into the photocatalytic effect of TiO2/MoS2 composite with co-exposed high-energy facets, and make a contribution to designing more efficient and stable photocatalysts.

Effects of strong coordination bonds at the axial or equatorial positions on magnetic relaxation for pentagonal bipyramidal dysprosium(III) single-ion magnets.

Three pentagonal bipyramidal mononuclear Dy(III) complexes based on amino-substituted nitrophenol and tetradentate amide ligands of formulas [Dy(Hbpen)(OPhNO2NH2Cl)Cl2] (1), [Dy(Hbpen)(OPhNO2NH2)Cl2] (2) and [Dy(Hbpen)(OPhNO2NH2Cl)3] (3) (Hbpen = N,N'-bis(2-pyridylmethyl)-ethylenediamine, OPhNO2NH2Cl = 2-amino-6-chloro-4-nitrophenol, and OPhNO2NH2 = 2-amino-4-nitrophenol) were isolated. X-ray diffraction studies illustrate that complexes 1 and 2 with one strongly coordinating phenol ligand at their equatorial positions have a similar structure except for a slight difference in the chloride substituent of the phenol ligand. Complex 3 possesses the same equatorial coordination as 1 but its apical positions are occupied by two other phenol ligands. Magnetic studies show that 1 and 2 are zero-field single-ion magnets (SIMs), and 3 exhibits field-induced SIM behavior. Upon removing the chloride substituent groups from the phenol ligand, the effective energy barrier enhances from 233.7 K (1) to 362.7 K (2) under external dc fields. The stronger quantum tunneling of magnetization observed for 3 in comparison with 1 shows the destructive influence of a strong phenoxyl oxygen ligand field contributing to the transverse component on the magnetic properties. A comparison of complex 2 and the reported Dy(III) analogue [Dy(Hbpen)Cl(OPhBr2NO2)2] with two phenol ligands (2,6-dibromo-4-nitrophenol) in the axial direction leads to the conclusion that the magnetic anisotropy is strongly dependent on the Dy-Ophenoxyl bond lengths. The results provide direct information vital to understanding how the strong coordination environment at the axial or equatorial positions influences the SIM behavior.

Hydrothermal Synthesis of Co-Exposed-Faceted WO3 Nanocrystals with Enhanced Photocatalytic Performance.

In this paper, rod-shaped, cuboid-shaped, and irregular WO3 nanocrystals with different co-exposed crystal facets were prepared for the first time by a simple hydrothermal treatment of tungstic acid colloidal suspension with desired pH values. The crystal structure, morphology, specific surface area, pore size distribution, chemical composition, electronic states of the elements, optical properties, and charge migration behavior of as-obtained WO3 products were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), fully automatic specific surface area and porosity analyzer, UV-vis absorption spectra, photoluminescence (PL) spectra, and electrochemical impedance spectroscopy (EIS). The photocatalytic performances of the synthesized pHx-WO3 nanocrystals (x = 0.0, 1.5, 3.0, 5.0, and 7.0) were evaluated and compared with the commercial WO3 (CM-WO3) nanocrystals. The pH7.0-WO3 nanocrystals with co-exposed {202} and {020} facets exhibited highest photocatalytic activity for the degradation of methylene blue solution, which can be attributed to the synergistic effects of the largest specific surface area, the weakest luminescence peak intensity and the smallest arc radius diameter.

Size controllable synthesis of ZSM-5 zeolite and its catalytic performance in the reaction of methanol conversion to aromatics.

ZSM-5 zeolites were hydrothermally synthesized with commercial silica sol, and the crystal size was controlled by adding silicalite-1 seed in the synthetic system. The crystal size of ZSM-5 was affected by the crystallization time of seed, seed content and seed size. ZSM-5 zeolites with controllable particle size in the range of 200-2200 nm could be obtained. The prepared samples with different particle sizes were used for the reaction of methanol conversion to aromatics (MTA). The results suggested that the HZSM-5 catalyst with small crystal size showed much longer catalyst lifetime and higher selectivity for C5 + hydrocarbons and aromatics, especially C9 + aromatics in the MTA reaction. Moreover, the introduction of zinc (Zn) into the HZSM-5 zeolites can considerably promote the selectivity to aromatics in the products. Zn modified HZSM-5 zeolites with different Zn loading amounts were prepared by the incipient wetness impregnation method, and the highest aromatics selectivity was obtained when the Zn loading was 1.0%. The improvement of methanol aromatization was ascribed to the synergistic effect of Brønsted acid sites and the newly formed Zn-Lewis acid sites.

Synthesis and Photocatalytic Activity of TiO2/CdS Nanocomposites with Co-Exposed Anatase Highly Reactive Facets.

In this work, TiO2/CdS nanocomposites with co-exposed {101}/[111]-facets (NH4F-TiO2/CdS), {101}/{010} facets (FMA-TiO2/CdS), and {101}/{010}/[111]-facets (HF-TiO2/CdS and Urea-TiO2/CdS) were successfully synthesized through a one-pot solvothermal method by using [Ti4O9]2- colloidal solution containing CdS crystals as the precursor. The crystal structure, morphology, specific surface area, pore size distribution, separation, and recombination of photogenerated electrons/holes of the TiO2/CdS nanocomposites were characterized. The photocatalytic activity and cycling performance of the TiO2/CdS nanocomposites were also investigated. The results showed that as-prepared FMA-TiO2/CdS with co-exposed {101}/{010} facets exhibited the highest photocatalytic activity in the process of photocatalytic degradation of methyl orange (MO), and its degradation efficiency was 88.4%. The rate constants of FMA-TiO2/CdS was 0.0167 min-1, which was 55.7, 4.0, 3.7, 3.5, 3.3, and 1.9 times of No catalyst, CdS, HF-TiO2/CdS, NH4F-TiO2/CdS, CM-TiO2, Urea-TiO2/CdS, respectively. The highest photocatalytic activity of FMA-TiO2/CdS could be attributed to the synergistic effects of the largest surface energy, co-exposed {101}/{010} facets, the lowest photoluminescence intensity, lower charge-transfer resistance, and a higher charge-transfer efficiency.

Hollow Square RodLike Microtubes Composed of Anatase Nanocuboids with Coexposed {100}, {010}, and {001} Facets for Improved Photocatalytic Performance.

In this study, hollow square rodlike microtubes composed of anatase nanocuboids with coexposed {100}, {010}, and {001} facets were successfully synthesized via a mild hydrothermal treatment method in the presence of NH4F by using layered H2Ti3O7 ribbons as the precursor. The precursor H2Ti3O7 ribbons were prepared from H+/Na+ ion-exchanged Na2Ti3O7. The suspension solution of protonated H2Ti3O7 ribbons was adjusted to desired pH values (0.5-13.0) prior to hydrothermal treatment. The elongated direction of the microtubes is along the b axis, according to the profile of the H2Ti3O7 ribbons. The transformation from staggered [Ti3O7]2- sheets to hollow square rodlike microtubes contained the formation and recombination of the dispersed octahedral [Ti(OH)2(OH2)4]2+ monomers, the formation and growth of the initial anatase nuclei, and the reassembly of the anatase nanocuboids along the b-axis direction during the continuous hydrothermal process. The degradation rate of pH 0.5-TiO2 was the highest at 1.66 × 10-2 min-1, which was 1.3, 1.5, 2.0, 2.3, and 18.4 folds higher than that of pH 3.0-TiO2 (1.27 × 10-2 min-1), pH 7.0-TiO2 (1.11 × 10-2 min-1), pH 5.0-TiO2 (0.83 × 10-2 min-1), P25-TiO2 (0.73 × 10-2 min-1), and the blank sample (0.09 × 10-2 min-1), respectively. Compared with P25-TiO2 and the other anatase TiO2 samples, pH 0.5-TiO2 exhibited the best photocatalytic activity, which was mainly attributed to its larger proportion of {010} (or {100}) facets, smaller crystalline size, higher band gap, and larger specific surface area.

Facile synthesis of TiO2/Ag3PO4 composites with co-exposed high-energy facets for efficient photodegradation of rhodamine B solution under visible light irradiation.

In this study, TiO2/Ag3PO4 composites based on anatase TiO2 nanocrystals with co-exposed {101}, {010}/{100}, {001} and [111]-facets and Ag3PO4 microcrystals with irregular and cubic-like polyhedron morphologies were successfully synthesized by combining hydrothermal and ion-exchange methods. The anatase TiO2 nanocrystals with different high-energy facets were controllably prepared via hydrothermal treatment of the exfoliated [Ti4O9]2-/[Ti2O5]2- nanosheet solutions at desired pH values. The Ag3PO4 microcrystal with different morphologies was prepared via the ion-exchange method in the presence of AgNO3 and NH4H2PO4 at room temperature, which was used as a substrate to load the as-prepared anatase TiO2 nanocrystals on its surface and to form TiO2/Ag3PO4 heterostructures. The apparent rate constant of the pH 3.5-TiO2/Ag3PO4 composite was the highest at 12.0 × 10-3 min-1, which was approximately 1.1, 1.2, 1.4, 1.6, 13.3, and 24.0 fold higher than that of pH 0.5-TiO2/Ag3PO4 (10.5 × 10-3 min-1), pH 7.5-TiO2/Ag3PO4 (10.2 × 10-3 min-1), pH 11.5-TiO2 (8.8 × 10-3 min-1), Ag3PO4 (7.7 × 10-3 min-1), blank sample (0.9 × 10-3 min-1), and the commercial TiO2 (0.5 × 10-3 min-1), respectively. The pH 3.5-TiO2/Ag3PO4 composite exhibited the highest visible-light photocatalytic activity which can be attributed to the synergistic effects of its heterostructure, relatively small crystal size, large specific surface area, good crystallinity, and co-exposed high-energy {001} and [111]-facets. The as-prepared TiO2/Ag3PO4 composites still exhibited good photocatalytic activity after three successive experimental runs, indicating that they had remarkable stability. This study provides a new way for the preparation of TiO2/Ag3PO4 composite semiconductor photocatalysts with high energy crystal surfaces and high photocatalytic activity.

Preparation of Ni/C porous fibers derived from jute fibers for high-performance microwave absorption.

Composites obtained by incorporating magnetic nanoparticles into porous carbon materials are promising in serving as microwave absorbing materials. In this study, Ni/C porous fibers were successfully synthesized through a simple in situ template method by using low-cost jute fibers as carbon source and template. The results showed that the Ni nanoparticles were uniformly loaded on the surface and hollow porous structure of the Ni/C porous fibers. Meanwhile, the content and size of the Ni nanoparticles on the Ni/C porous fibers can be controlled. Due to a suitable filling content, the synergistic effect of dielectric loss, interface polarization loss, magnetic loss and porous structure of the Ni/C porous fibers, an excellent microwave absorption performance was achieved. The minimum reflection loss value reached -43.0 dB, and a reflection loss value less than -10 dB was in the frequency range of 11.2-16.1 GHz with 2.0 mm thickness. In particular, under matching thickness (1.5-3.5 mm), the values of all the reflection loss peaks were below -20.0 dB. It is believed that this work can not only provide a new way to design excellent carbon-based microwave absorbing materials, but also offer an effective design strategy to synthesize biomass nanocomposites.

Microwave-Assisted Synthesis of High-Energy Faceted TiO2 Nanocrystals Derived from Exfoliated Porous Metatitanic Acid Nanosheets with Improved Photocatalytic and Photovoltaic Performance.

A facile one-pot microwave-assisted hydrothermal synthesis of rutile TiO2 quadrangular prisms with dominant {110} facets, anatase TiO2 nanorods and square nanoprisms with co-exposed {101}/[111] facets, anatase TiO2 nanorhombuses with co-exposed {101}/{010} facets, and anatase TiO2 nanospindles with dominant {010} facets were reported through the use of exfoliated porous metatitanic acid nanosheets as a precursor. The nanostructures and the formation reaction mechanism of the obtained rutile and anatase TiO2 nanocrystals from the delaminated nanosheets were investigated. The transformation from the exfoliated metatitanic nanosheets with distorted hexagonal cavities to TiO2 nanocrystals involved a dissolution reaction of the nanosheets, nucleation of the primary [TiO6]8- monomers, and the growth of rutile-type and anatase-type TiO2 nuclei during the microwave-assisted hydrothermal reaction. In addition, the photocatalytic activities of the as-prepared anatase nanocrystals were evaluated through the photocatalytic degradation of typical carcinogenic and mutagenic methyl orange (MO) under UV-light irradiation at a normal temperature and pressure. Furthermore, the dye-sensitized solar cell (DSSC) performance of the synthesized anatase TiO2 nanocrystals with various morphologies and crystal facets was also characterized. The {101}/[111]-faceted pH2.5-T175 nanocrystal showed the highest photocatalytic and photovoltaic performance compared to the other TiO2 samples, which could be attributed mainly to its minimum particle size and maximum specific surface area.

Facile Formation of Anatase/Rutile TiO2 Nanocomposites with Enhanced Photocatalytic Activity.

Anatase/rutile mixed-phase TiO2 nanoparticles were synthesized through a simple sol-gel route with further calcination using inexpensive titanium tetrachloride as a titanium source, which effectively reduces the production cost. The structural and optical properties of the prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis adsorption. The specific surface area was also analyzed by Brunauer-Emmett-Teller (BET) method. The anatase/rutile mixed-phase TiO2 nanocomposites containing of rod-like, cuboid, and some irregularly shaped anatase nanoparticles (exposed {101} facets) with sizes ranging from tens to more than 100 nanometers, and rod-like rutile nanoparticles (exposed {110} facets) with sizes ranging from tens to more than 100 nanometers. The photocatalytic activities of the obtained anatase/rutile mixed-phase TiO2 nanoparticles were investigated and compared by evaluating the degradation of hazardous dye methylene blue (MB) under ultraviolet light illumination. Compared to the commercial Degussa P25-TiO2, the mixed-phase TiO2 nanocomposites show better photocatalytic activity, which can be attributed to the optimal anatase to rutile ratio and the specific exposed crystal surface on the surface. The anatase/rutile TiO2 nanocomposites obtained at pH 1.0 (pH1.0-TiO2) show the best photocatalytic activity, which can be attributed to the optimal heterojunction structure, the smaller average particle size, and the presence of a specific exposed crystal surface. The enhanced photocatalytic activity makes the prepared anatase/rutile TiO2 photocatalysts a potential candidate in the removal of the organic dyes from colored wastewater.

Cancer risk assessment of soils contaminated by polycyclic aromatic hydrocarbons in Shanxi, China.

To assess the human cancer risk exposed to soil contaminated by polycyclic aromatic hydrocarbons (PAHs) in Shanxi province, China, the total 33 samples in the surface soil were collected from 11 cities, and the priority 15 PAHs were analyzed using gas chromatography-mass spectrometry after the soxhlet extraction and silica-alumina column purification. As a result, the levels of ∑15PAH in soil varied from 66.2 to 2633 ng/g dry weight (dw) with a mean of 732 ng/g dw, and seven carcinogenic PAHs made up 42-69% of the total priority PAHs and had an average value of 367 (in the range of 33.2 to 1181) ng/g dw. Accordingly, the total concentrations of benzo[a]pyrene equivalents (BaPeq) for 15 PAHs ranged from 10.3 to 358 (average 98.3) ng/g dw, and the seven carcinogenic BaPeq accounted for above 90%. Subsequently, the possible sources of PAHs in soil were identified by isomer ratios, demonstrating that the combustion contributed to the main source. Finally, the incremental lifetime cancer risks (ILCR) of soil contaminated by 15 priority PAHs were estimated using the targeted chemical-specific approach. ILCR values were considered to be greater than 1 × 10-6 in 16 of 33 sites and followed a decreasing trend of adulthood > childhood > adolescence. Subsequently, the analysis of variance was performed by average ILCR value among the 11 cities (n = 3, p < 0.01), which indicated that the potential low cancer risk significantly increased for nearby residents in two areas, including Datong and Xinzhou, with the ILCR values of 4.61 ±â€¯1.93 and 3.92 ±â€¯2.54 per million, respectively. Therefore, the consumption of traditional coal should be controlled and partially replaced with the alternative energy sources. And the rigorous monitoring should be termly warranted to avoid the cancer risk for human being in agricultural area of Shanxi, China.

NiFe2O4 nanoparticles supported on cotton-based carbon fibers and their application as a novel broadband microwave absorbent.

In this work, NiFe2O4 nanoparticles were successfully supported on cotton-based carbon fibers through a flexible two-step approach consisting of calcination of cotton in a N2 atmosphere and subsequent hydrothermal reaction. The incorporation of the NiFe2O4 nanoparticles into cotton-based carbon fibers resulted in better impedance matching, leading to better microwave absorption performance than cotton-based carbon fibers and NiFe2O4 nanoparticles. For NiFe2O4/carbon fibers, reflection loss (RL) values less than -10 dB were obtained in the frequency range of 11.5-18 GHz with 2.4 mm thickness, which covered the entire Ku-band (from 12 to 18 GHz). Meanwhile, when the matching thickness was 3.2 mm, the RL values less than -10 dB were in the range of 8.0-12.7 GHz, which covered the entire X-band (from 8 to 12 GHz). This excellent and interesting microwave absorption performance can satisfy multiple applications. Owing to the characteristics of a cost-effective synthetic route, low density and excellent microwave absorption, the NiFe2O4/carbon fibers have a promising future in X-band and Ku-band absorption.

Delithation, Exfoliation, and Transformation of Rock-Salt-Structured Li2TiO3 to Highly Exposed {010}-Faceted Anatase.

{010}-Facet-exposed anatase TiO2 crystals exhibit the highest photoreactivity among the exposed facets. To obtain a higher exposure rate of this facet, the work investigated the transformation of the nanosheets with cavities within the layers derived from a rock-salt-structured Li2TiO3 precursor. All the lithium ions were extracted from the precursor by H+/Li+ ion exchange in HCl aqueous solutions, and after tetramethylammonium ions were intercalated, the precursor can delaminated into the nanosheets. The [TiO3]2- nanosheets were hydrothermally treated under different temperatures and pH values. The results showed that the anatase phase was formed in a wider range of pH and temperature, compared with using nanoribbons of [Ti4O9]2- and nanosheets of [Ti1.73O4]1.07-. At low pH, [111]-faceted nanorod-shaped anatase nanocrystals were formed preferentially, and the nanocrystals preferentially grow along the [001] direction with the increase of solution pH, leading to a large percentage of {010} facets on their surface. The photocatalytic activity increases with the increase of exposure rate of {010} facets.

Photocatalytic and dye-sensitized solar cell performances of {010}-faceted and [111]-faceted anatase TiO2 nanocrystals synthesized from tetratitanate nanoribbons.

The morphology and exposed facet of the anatase-type TiO2 are very important to improve the photocatalytic activity and photovoltaic performance in dye-sensitized solar cells. In this work, we report the synthesis and the photocatalytic and dye-sensitized solar cell performances of anatase-type TiO2 single nanocrystals with exposed {010}- and [111]-facets and with various morphologies by using exfoliated tetratitanate nanoribbons as precursors. The precursor nanoribbons were prepared from the exfoliation of the protonated and, subsequently, tetramethylammonium/H(+) ion-exchanged K2Ti4O9. The colloidal suspension containing the nanoribbons was hydrothermally heated with a microwave-assistance at temperatures from 120 to 190 °C after pH was adjusted to 0.5-14. The dependence of the crystalline phases on temperature and pH indicated that anatase single phase can be obtained at pH 3-13 whereas temperatures higher than 160 °C. The [111]-faceted nanorod-shaped anatase nanocrystals were formed preferentially at pH ≤ 3, whereas the {010}-faceted anatase nanocrystals with morphologies of rhombic, cuboid, and spindle were preferentially at pH ≥5. The morphology observation revealed that the nanoribbons were transformed to anatase nanocrystals mainly by the topotactic structural transformation reaction accompanied by an Ostwald ripening reaction, and pH of the reaction solution took a critical role in the crystal morphology change. At pH ≤1, the mixture of anatase, rutile, and brookite were obtained at higher temperature conditions. The photocatalytic activity and photovoltaic performance were enhanced in an order of surface without a specific facet < [111]-faceted surface < {010}-faceted surface.

A 3D chiral porous In(III) coordination polymer with PtS topological net.

The solvothermal reaction of In(III) and 1,2,4,5-benzeneteracarboxylic acid with the presence of piperazine leads to the generation of a novel 3D chiral porous coordination polymer with PtS topological net. Interestingly, the resulting crystals were not a racemic mixture but enantiomeric excess, which was confirmed by the measurement of optical rotation of bulk samples using solid vibrational circular dichroism (VCD) spectra and the solid circular dichroism (CD) spectra based on large crystals from one crystallization. High-pressure CO(2) and CH(4) adsorption measurement at 298 K reveals that activated 1 can absorb 45.8 cm(3) (STP)/g CO(2) at 22 atm and 22.5 cm(3) (STP)/g CH(4) at 25 atm.