Growth, Mechanical, Thermal and Spectral Properties of Cr3+∶MgMoO4 Crystal

This paper reports the growth, mechanical, thermal and spectral properties of Cr3+∶MgMoO4 crystals. The Cr3+∶MgMoO4 crystals with dimensions up to 30 mm×18 mm×14 mm were obtained by TSSG method. The absorption cross-sections of 4A2→4T1 and 4A2→4T2 transitions are 12.94×10−20 cm2 at 493 nm and 7.89×10−20 cm2 at 705 nm for E//Ng, respectively. The Cr3+∶MgMoO4 crystal shows broad band emission extending from 750 nm to 1300 nm with peak at about 705 nm. The emission cross-section with FWHM of 188 nm is 119.88×10−20 cm2 at 963 nm for E//Ng. The investigated results showed that the Cr3+∶MgMoO4 crystal may be regarded as a potential tunable laser gain medium

Photoelectrochemical Performance of Nb-doped TiO_2 Nanoparticles Fabricated by Hydrothermal Treatment of itanate Nanotubes in Niobium Oxalate Aqueous Solution

Nb-doped TiO_2 nanoparticles were prepared by hydrothermal treatment of titanate nanotubes in niobium oxalate aqueous solution. The effect of Nb doping and rutile content on the photoelectrochemical performance based on TiO_2 powder electrodes was investigated. The results show that Nb-doped TiO_2 with a small amount of rutile exhibits the enhanced photoelectric conversion efficiency for dye-sensitized solar cell. The highest photoelectric conversion efficiency of 8.53% is obtained for 1% Nb-TiO_2 containing a small amount of rutile. When a small amount of rutile contained in 2% Nb-TiO_2, a higher photoelectric conversion efficiency of 8.77% is achieved

Controllable hydrothermal synthesis of rutile TiO2 hollow nanorod arrays on TiCl4 pretreated Ti foil for DSSC application

Rutile TiO2 nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl4 pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO2 nanorod arrays (H-TNRs). The TiCl4 pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl4 concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of similar to 1.5 mu m and diameter of similar to 200 nm, obtained on 0.15 M TiCl4 pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 degrees C-H-TNRs photoanode obtained from the 0.15-TiCl4-TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode. (C) 2014 Elsevier Inc. All rights reserved

Enhanced photocatalytic performance of platinized CdS/TiO2 by optimizing calcination temperature of TiO2 nanotubes

TiO2 nanotubes were prepared by hydrothermal treatment of TiO2 powder in NaOH aqueous solution and then calcined at various temperatures. The post-calcination treated TiO2 nanotubes were decorated with CdS by wetness impregnation and subsequently sulfurization to fabricate CdS/TiO2 composites. The photocatalytic performance of CdS/TiO2 composites toward hydrogen production from water splitting was investigated. The results show that the calcination temperature of TiO2 nanotubes has a significant effect on the photocatalytic performance of CdS/TiO2. With the increase of calcination temperature from 300 to 500 degrees C, the crystallinity of TiO2 nanotubes is increased resulting in the enhanced photocatalytic performance of CdS/TiO2. When the calcination temperature is higher than 500 degrees C, TiO2 nanotubes gradually transform into nanorods and finally completely collapse, which leads to the decrease of photocatalytic performance of CdS/TiO2. The CdS/TiO2 composite with TiO2 nanotubes calcined at 500 degrees C exhibits the highest hydrogen evolution rate, which could be attributed to its 1 D nanotubular structure and good crystallinity. (C) 2014 Elsevier Ltd. All rights reserved

Nano-CdS confined within titanate nanotubes for efficient photocatalytic hydrogen production under visible light illumination

CdS nanoparticles were confined within titanate nanotubes (TNTs) by an ion-exchange reaction and a subsequent sulfurization process. Prior to the ion-exchange reaction, the exterior surfaces of the TNTs were modified by a silane coupling agent to make CdS nanoparticles selectively deposit on the inner wall. The composites were characterized by high-resolution transmission electron microscopy, powder x-ray diffraction, inductively coupled plasma atomic emission spectrometry, N-2 adsorption-desorption and UV-vis absorption spectra. The results confirm that CdS in the range of 2-3 nm in diameter are confined within the inner cavity of the TNTs. CdS confined within TNTs shows a significant blue-shift of the absorption band edge compared with CdS nanoparticles deposited on the exterior surface of TNTs. Also the TNTs-confined CdS composite exhibits enhanced photocatalytic activity and photostability for hydrogen evolution under visible light illumination due to the quantum size effect of CdS as a result of the spatial confinement effect of the TNTs

Preparation of titania nanotube-Cd0.65Zn0.35S nanocomposite by a hydrothermal sulfuration method for efficient visible-light-driven photocatalytic hydrogen production

Titania nanotube-Cd0.65Zn0.35S nanocomposite (Cd0.65Zn0.35S-TiO2) was synthesized from titanate nanotubes for ion change of Cd2+ and Zn2+ followed by hydrothermal sulfuration treatment using thiourea as sulfur source. The Cd0.65Zn0.35S-TiO2 with enhanced crystallinity of TiO2 nanotube can be obtained by increasing hydrothermal temperature from 90 degrees C to 120 degrees C. And further increasing hydrothermal temperature to 150 degrees C, TiO2 nanotubes collapse and transform into irregular shaped particles. The photocatalytic activity for hydrogen production of the prepared Cd0.65Zn0.35S-TiO2 with different hydrothermal temperature was investigated under visible-light irradiation. The result shows that the Cd0.65Zn0.35S-TiO2 with hydrothermal temperature of 120 degrees C presents the highest hydrogen evolution rate and photostability, which can be attributed to a rapid charge transfer at the interface between Cd0.65Zn0.35S and TiO2 nanotube due to the increased crystallinity and unique 1-D nanotubular structure of TiO2. (C) 2014 Elsevier B.V. All rights reserved

Effect of Ordered TiO2 Nanotube Array Substrate on Photocatalytic Performance of CdS-Sensitized ZnO Nanorod Arrays

The composite photocatalyst with layered nanoarray structure, CdS-sensitized ZnO nanorod arrays (ZnONRA/CdS) grown on ordered TiO2 nanotube arrays (TiO(2)NTA), was constructed. The performance of composite photocatalyst toward to hydrogen production from water splitting was investigated. The ZnONRA/CdS composite photocatalyst with the substrate layer of ordered TiO(2)NTA has the enhanced rate of hydrogen production and the improved photostability. It may be attributed to the one-dimensional structure of TiO(2)NTA at the bottom of ZnONRA/CdS composite photocatalyst, which provides a direct transfer pathway of photoinjected electrons along the photoanode to enhance charge-collection efficiency and consequently reduce electron-hole recombination

Effect of Different Types of Phosphate Fertilizer on Phosphorus Absorption and Desorption in Acidic Red Soil of Southwest China

The effects of different types of phosphate fertilization on the phosphorus (P) adsorption-desorption in low-P red soil remain unclear. A field plot location test was carried out, and fifteen red soil samples were collected at depths of 0–20 cm from five phosphate fertilizers (CK—no-phosphate, SSP—single superphosphate, CMP—calcium magnesium phosphate, MAP—monoammonium phosphate, and DAP—diammonium phosphate) after the maize was harvested to evaluate the soil physicochemical properties, P adsorption, and desorption characteristics. The structural equation model (SEM) and adjacent tree method (ABT) were used to quantitatively analyze the relative contribution of P adsorption and desorption. The yield, P accumulation, and the P use efficiency of maize were the highest under SSP and CMP treatments. The P adsorption amount was CK > DAP > MAP > CMP > SSP, and the P desorption amount was DAP > MAP > CMP > SSP > CK. Compared with the CK treatment, P adsorption of other P treatments reduced by an average of 21.4%, while P desorption increased by 154.8%. The effect of different types of phosphate fertilizers on soil P adsorption was mainly through regulation of soil organic matter (SOM) and Olsen P, and the effect on soil P desorption was mainly through regulation of SOM and CaCO3. Al2O3 had the greatest effect on P adsorption with a relative contribution rate of 31.52%, and SOM had the greatest effect on P desorption with a relative contribution rate of 53.04%. SSP and CMP treatments had an optimal matching with acidic red soil, which can promote P adsorption, effectively slow down P loss, improve P utilization, and increase crop yield

Experimental study on the effect of inverted aperture plate temperature on frosting characteristics under rising flow considering edge effect

To reduce the negative impact of frost formation on cold surfaces in low-temperature environments, metal wire mesh can be set in the air flow direction from the cold surface to reduce air humidity. To quantitatively determine the effectiveness of dehumidification after passing through a metal wire, the frosting process needs to be studied. To analyze the mechanism of frost formation under the horizontal wire mesh surface, the wire mesh was simplified as a flat plate with holes, or aperture plate, with plate temperature varying at a range of -15.0 °C to -5.0 °C. The results show that, as the plate temperature decreases, the droplet condensation and growth and droplet solidification stages gradually decrease, the average frost layer thickness and frost layer growth rate rise, and overall frost layer surface roughness increases. For a frosting duration of 1,800 s, compared to -5.0 °C, the average frost layer thickness from -7.5 °C to -15.0 °C inside the hole increased by 56.68 % and 156.41 %, while the plate edge region away from the hole increased by 40.76 % and 169.92 %, respectively. The reverse melting frequency gap between the inside hole region and the plate edge region away from the hole increases with the decreasing aperture plate temperature. At -15.0 °C, the reverse melting frequency inside the hole is 5.00 × 10−3 Hz lower than in the region of the plate edge away from the hole. The results of this article are beneficial for understanding the frosting process of wire mesh or perforated-fin heat exchanger.Ministry of Science and ICT of the Republic of Korea; National Natural Science Foundation of China, NSFC, (52076013); Ministry of Science and Technology of the People's Republic of China, MOST; National Research Foundation of Korea, NRF; Beijing Municipal Science and Technology Commission, Adminitrative Commission of Zhongguancun Science Park, (3212024