Inorganic Chemistry Frontiers
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2017
·Vol. 4
·期 6
·935-945
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IF 4.036
Jiantao Feng,Yechen Wang,Yanhui Hou,Liangchao Li
A series of yolk–shell ZnFe2O4@reduced graphite oxide@TiO2 (ZFO@RGO@TiO2) microspheres with different void sizes and TiO2 shell thicknesses has been successfully synthesized by combining a layer-by-layer coating process and chemical etching route. Compared to pure ZFO and hierarchical ZFO@SiO2@RGO@TiO2, the as-synthesized yolk–shell microspheres exhibited significantly enhanced microwave absorption properties in terms of effective bandwidth and reflection loss. Among these, the minimum reflection loss of the as-synthesized yolk–shell microspheres with a thickness of 2.6 mm could reach up to −44.3 dB at 15.92 GHz, and their effective absorption bandwidth at less than −10 dB was 4.1 GHz. In addition, as the shell thickness of the yolk–shell microspheres decreased, the frequency corresponding to the minimum reflection loss shifted to the high-frequency range. Hence, these obtained yolk–shell microspheres are potential new candidates for high-frequency shielding and lightweight microwave absorbing materials.
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Progress in Natural Science-Materials International
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2016
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IF 1.753
Yu Bai,Chunlei Wang,Xingyi Zhou,Junling Lu,Yujie Xiong
Pd typically exhibits relatively low catalytic activity in CO oxidation, as CO is apt to be adsorbed on Pd to poison the surface for O 2 activation. In this Letter, we report that this limitation can be overcome by integrating Pd with TiO 2 . The TiO 2 was coated on Pd nanocubes with a controllable thickness using atomic layer deposition (ALD) method. Given the different work functions of TiO 2 and Pd, the electrons in TiO 2 semiconductor will flow toward Pd. With the electron density increased on Pd, the adsorption of CO to Pd will be weakened while the oxygen activation can be facilitated. Meanwhile, the interface-confined sites at Pd-TiO 2 may further enhance the oxygen activation. As the species adsorption and activation are strongly correlated with electron density, the performance of Pd-TiO 2 in CO oxidation turns out to depend on the TiO 2 thickness, which determines the number of transferred electrons, within a certain range (<1.8 nm). This work provides a new strategy for enhancing catalytic performance through tailoring charge densities in hybrid catalysts.
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ACS Sustainable Chemistry & Engineering
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2017
·
IF 5.951
Meiqi Chang,Yanhua Song,Jie Chen,Lei Cui,Zhan Shi,Ye Sheng,Haifeng Zou
A novel multifunctional core–shell, yolk–shell SiO2@TiO2:Eu3+/Sm3+ and hollow TiO2:Eu3+/Sm3+ structures were successfully synthesized. The relationship between morphology/ions doping and multifunctional properties including photoluminescence and photocatalysis has been discussed in detail for the first time using systematic characterization techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence (PL), ultraviolet–visible light (UV-vis) analysis, Fourier transform infrared (FT-IR) spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). Upon ultraviolet (UV) excitation, the products show the characteristic red and orange–red emission lines of Eu3+ and Sm3+, respectively. In addition, Judd–Ofelt intensity parameters (Ω2, Ω4) were used to investigate the symmetry and coordination state of Eu3+ ions in the products with different morphologies. The relative luminescence intensities were in the following order: yolk–shell > core–shell > hollow structure. This phenomenon can be ascribed to the unique yolk–shell configuration, which possesses appropriate interior cavity used for multiple reflections and scattering, allowing for more-efficient utilization of the light. Moreover, compared with yolk–shell and hollow structure, the core–shell spheres exhibit excellent photoactivity for the degradation of MO, because the existence of Ti–O–Si bonds increases the surface acidity of the sample, thereby activating the oxidation reaction. In addition, the electron activation in the TiO2 matrix can be facilitated through intermediate oxygen atoms. Moreover, products doped with different rare-earth (RE3+) ions exhibited distinguishable photocatalytic performance. The surfactant-free method provides a promising route toward the development of multifunctional materials for many applications in photocatalysis and PL.
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SENSORS AND ACTUATORS B-CHEMICAL
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2016
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IF 4.758
Weiwei Meng,Lei Dai,Wei Meng,Huizhu Zhou,Yuehua Li,Zhangxing He,Ling Wang
Mixed-potential type NH 3 sensors were fabricated using La 10 Si 5.5 Al 0.5 O 27 (LSAO) consisting of a porous layer and a dense layer as solid electrolyte and TiO 2 as the sensing electrode. The effect of a LSAO porous layer and TiO 2 phase transformation on sensor performances was investigated. The porous layer of LSAO electrolyte obviously enhanced sensor performance. Compared with the sensor without a LSAO porous layer, the sensor with LSAO porous layer exhibited larger responding potential values and higher sensitivity due to the enhanced three phase interface length. Anatase-TiO 2 (a-TiO 2 ) based sensor exhibited better sensing performance than rutile-TiO 2 (r-TiO 2 ) based sensor at the examined temperature range. A-TiO 2 transformation toward r-TiO 2 resulted in poor sensing performances of the sensor. The best sensing characteristics were achieved for the NH 3 sensor with a-TiO 2 sensing electrode calcined at 900 °C for 3 h. The potential values of the sensor response to NH 3 linearly depended on the logarithm of NH 3 concentrations at 450–600 °C and the sensitivity reached 169.7 mV/decade in the range of 50–400 ppm at 500 °C. At the same time, the sensor exhibited well anti-interference capability to H 2 , NO, CH 4 and CO 2 , but a little cross-sensitivity toward NO 2 was observed. High temperature treatment (>900 °C) caused a-TiO 2 transformation into r-TiO 2 and V 2 O 5 additions were conducive to TiO 2 phase transformation.
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BIOSENSORS & BIOELECTRONICS
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2016
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IF 7.476
Honghong Chang,Jia Lv,Haochun Zhang,Bing Zhang,Wenlong Wei,Yan Qiao
Chloramphenicol (CAP) is an antibiotic used for a variety of infections, however, it is banned for use in food-producing animals due to its hazards to humans blood . Herein, the highly sensitive photoresponsive colorimetric immunoassay was exploited based on AgI/TiO 2 heterojunction nanomaterials . Firstly, chitosan modified AgI/TiO 2 photocatalyst (CS-AgI/TiO 2 ) was synthesized by deposition-precipitation method, which was characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR). Then, by utilizing CS-AgI/TiO 2 labeled CAP antibody as tags, a novel competitive-type immunoassay was constructed for detection of CAP on the surface of CAP-BSA modified magnetic bead. The color development of 3,3 ′ ,5,5 ′ -tetramethylbenzidine (TMB) was obtained under visible light irradiation (λ≥420 nm) and the assay was carried out in pH 3.0 ABS buffer solution by UV–Vis spectrophotometry . Under optimal conditions, the absorbance values decreased with the increasing of CAP levels in sample, which exhibited linear in the range of 0.03–12.53 nM with a detection limit of 0.03 nM. Meanwhile, the selectivity , repeatability, and stability were acceptable. Excitedly, no significant difference was observed for detection of the spiked CAP in the real food samples with the referenced values.
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APPLIED CATALYSIS A-GENERAL
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2016
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IF 4.012
Wenwen Ma,Yan Xu,Kaiwen Ma,Hong Zhang
H 3 PW 12 O 40 /TiO 2 (abbreviated PW 12 /TiO 2 ) nanofibers catalysts have been successfully prepared via calcinating off the respective electrospun PVP/[PW 12 + Ti(OC 4 H 9 ) 4 ] composite nanofibers for the first time and they show ultra-deep desulfurization catalytic performance in mild conditions. PW 12 /TiO 2 nanofibers consist of anatase phase TiO 2 and Keggin structure PW 12 , the diameter of which is approximately 100 nm. Compared with PW 12 /TiO 2 nanoparticles, 40 wt.% PW 12 /TiO 2 nanofibers (the weight percentage of PW 12 loading on TiO 2 nanofibers was 40%) exhibited the higher catalytic activity under the same conditions. DBT could be removed completely within 30 min at 70 °C using 0.02 g 40 wt.% PW 12 /TiO 2 nanofibers as catalysts, when ionic liquid (IL) [Bmim]PF 6 was as extraction agent. Additionally, sulfur removal of different substrates decreased in the following orders: DBT > BT > 4,6-DMDBT under the same conditions. Even after 5-times recycling, the catalytic activity of 40 wt.% PW 12 /TiO 2 nanofibers was not significant decreased. As a total result, these novel PW 12 /TiO 2 nanofibers can be used to deeply desulfurize in the industry.
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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2017
·Vol. 85
·期 2
·394-401
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IF 1.575
Qian Xin,Han Huanre,Chen Yulong,Yuan Ye
Abstract In this study, an attempt is done to synthesize anatase/brookite/rutile TiO 2 nanocomposites via a simple solvothermal method with hydrochloric acid, dehydrated ethanol, and titanium butoxide in a sol−gel environment. The effect of preparation temperature on the content of each phase, crystallite size, morphology, and photocatalytic activity was systemically studied. The structures of the products prepared under different temperatures were characterized using X-ray diffraction analysis, transmission electron microscopy, Raman spectra, and BET surface area. The optical properties were measured by UV–vis diffuse reflectance spectra. Besides, the photocatalytic activities were evaluated by performing the degradation of rhodamine B azo dye under UV−vis radiation. The results reveal that the content of different phases and crystallite size can be tailored via tuning the solvothermal condition. In addition, the obtained TiO 2 nanocomposites are a kind of mesoporous materials and have large BET surface area, narrow pore size distribution, and low band gap, which exhibit excellent photocatalytic performance (of activity about 4.40 times that of Degussa TiO 2 P25). Through examining the photocatalytic stability, the obtained TiO 2 nanocomposites exhibit a very stable photocatalytic performance. Therefore, the current method to TiO 2 preparation could provide a simple and reliable route for developing photocatalytic materials with high photocatalytic activity. Graphical abstract
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PROCESS BIOCHEMISTRY
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2017
·
IF 2.497
Zhen Gao,Jianlin Chu,Tianyue Jiang,Tingting Xu,Bin Wu,Bingfang He
According to the purification characteristics of lipase from Burkholderia ambifaria YCJ01, mesoporous TiO 2 was functionalized by phenylaminopropyl trimethoxysilane (Ph-TiO 2 ) for lipase immobilization. This support permitted one step immobilization and purification of lipase YCJ01 via hydrophobic interactions from crude fermentation supernatant. The activity of immobilized lipase was 6119.2 U/g support with 12.8 mg/g support of enzyme loading. The ratio of the activity of immobilized lipase to decrease activity in the supernatant after immobilization reached 2.2, which indicated that the immobilized lipase molecules exhibited a dramatic hyperactivation. In comparison with free lipase, immobilized lipase showed significantly improved pH stability and thermalstability. The Ph-TiO 2 /YCJ01 biocomposite was analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis . The result indicated lipase was efficiently immobilized on Ph-TiO 2 surface. Finally, the research about cinnamyl acetate synthesis suggested that Ph-TiO 2 /YCJ01 had enhanced catalytic efficiency compared with free lipase. In solvent free medium, the yield of 96.9% was obtained after one operation, and maintained more than 80% of yield after ten reaction cycles.
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TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
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2016
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IF 1.34
Ya-hui YANG,Ren-rui XIE,Hang LI,Can-jun LIU,Wen-hua LIU,Fa-qi ZHAN
A novel WO 3– x /TiO 2 film as photoanode was synthesized for photoelectrocatalytic (PEC) reduction of CO 2 into formic acid (HCOOH). The films prepared by doctor blade method were characterized with X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The existence of oxygen vacancies in the WO 3– x was confirmed with an X-ray photoelectron spectroscopy (XPS), and the accurate oxygen index was determined by a modified potentiometric titrimetry method. After 3 h of photoelectrocatalytic reduction, the formic acid yield of the WO 3– x /TiO 2 film is 872 nmol/cm 2 , which is 1.83 times that of the WO 3 /TiO 2 film. The results of PEC performance demonstrate that the introduction of WO 3– x nanoparticles can improve the charge transfer performance so as to enhance the performance of PEC reduction of CO 2 into formic acid.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2016
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IF 3.782
Hui Feng,Niu Tang,Songbai Zhang,Bo Liu,Qingyun Cai
A novel (CdS-Mn/MoS 2 /CdTe)-sensitized TiO 2 nanotube arrays (NTAs) photoelectrode has been prepared by electrodeposite, successive ionic layer adsorption and reaction (SILAR) coupled with hydrothermal method . When a ZnS layer was added on the top of CdS-Mn/MoS 2 /CdTe/TiO 2 , a notable red-shift and high absorption was observed in the visible light region. The photocurrent density (mA/cm 2 ) systematically increases from TiO 2 NTAs (0.43), CdTe/TiO 2 (1.09), MoS 2 /CdTe/TiO 2 (1.80), CdS-Mn/MoS 2 /CdTe/TiO 2 (2.40), to ZnS/CdS-Mn/MoS 2 /CdTe/TiO 2 (3.41) under visible light irradiation, due to the type-II semiconductor heterostructures comprising multiple components with a staggered band offset. Such a heterostructure possesses an enhanced photocatalytic performance towards degradation of organic contaminant, e.g. P-Nitrophenol (PNP) and Rhodamine B (RhB) .
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Micromachines
·
2017
·Vol. 8
·期 2
·55
·
IF 1.833
Peng Zhou,Wangnan Li,Tianhui Li,Tongle Bu,Xueping Liu,Jing Li,Jiang He,Rui Chen,Kunpeng Li,Juan Zhao,Fuzhi Huang
Flexible electronics have attracted great interest in applications for the wearable devices. Flexible solar cells can be integrated into the flexible electronics as the power source for the wearable devices. In this work, an ultrasonic spray-coating method was employed to deposit TiO2nanoparticles on polymer substrates for the fabrication of flexible perovskite solar cells (PSCs). Pre-synthesized TiO2nanoparticles were first dispersed in ethanol to prepare the precursor solutions with different concentrations (0.5 mg/mL, 1.0 mg/mL, 2.0 mg/mL) and then sprayed onto the conductive substrates to produce compact TiO2films with different thicknesses (from 30 nm to 150 nm). The effect of the different drying processes on the quality of the compact TiO2film was studied. In order to further improve the film quality, titanium diisopropoxidebis(acetylacetonate) (TAA) was added into the TiO2-ethanol solution at a mole ratio of 1.0 mol % with respect to the TiO2content. The final prepared PSC devices showed a power conversion efficiency (PCE) of 14.32% based on the indium doped tin oxide coated glass (ITO-glass) substrate and 10.87% on the indium doped tin oxide coated polyethylene naphthalate (ITO-PEN) flexible substrate.Keywords:ultrasonic spray;titanium oxide;flexible perovskite solar cells;low temperature;large area
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APPLIED THERMAL ENGINEERING
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2017
·
IF 3.444
Xue-Feng Shao,Song-Ping Mo,Ying Chen,Tao Yin,Zhi Yang,Li-Si Jia,Zheng-Dong Cheng
The solidification behavior of hybrid nanofluids containing TiO 2 nanotubes (TiNTs) and nanoplatelets (TiNPs) was investigated in 10 freeze–melt cycles and the results were compared with those of individual TiNT and TiNP nanofluids. Hybrid TiO 2 nanofluids showed lower supercooling degrees because of larger surface area exposed to water, and shorter freezing time as a result of higher thermal conductivities, compared with individual TiNT and TiNP nanofluids. A maximum reduction of 5.27 ± 0.2 °C in supercooling degree and 56.42% in freezing time were achieved for hybrid nanofluids containing 25% and 50% TiNPs, respectively. The supercooling degree and freezing time of hybrid nanofluids showed less of an increase across 10 freeze–melt cycles as they have better dispersion stability compared with individual nanofluids. Evidently, the smallest increase of 0.68 ± 0.2 °C in supercooling degree and 29.85% in freezing time was achieved in 0.1 wt.% hybrid nanofluid compared with 2.02 ± 0.2 °C and 130.37% for individual TiNT nanofluids and 3.98 ± 0.2 °C and 101.08% for individual TiNP nanofluids. These promising performances highlight the outstanding thermal energy storage applications of hybrid nanofluids.
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