APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
·
IF 9.446
Jibo Liu,Huijie Shi,Qi Shen,Chenyan Guo,Guohua Zhao
Aiming at improving the efficiency of photoelectrocatalytic (PEC) CO 2 conversion to methanol, a heterogeneous photoelectrocatalyst was prepared by covalently binding a Ru(II) metal-organic complex (Ru-Py) containing exposed pyridyl on the periodic TiO 2 nanotube arrays (TNTAs). PEC characterization indicated that the Ru-Py/TNTAs photocathode exhibited excellent PEC CO 2 reduction activity in aqueous solution. The initial CO 2 reduction potential on Ru-Py/TNTAs photocathode reached −0.4 V (vs. NHE) under simulated solar irradiation. The cathodic photocurrent response of Ru-Py/TNTAs in CO 2 -satuarated aqueous solution was about 1.79 mAcm −2 , which was 2.4 times that of TNTAs . It may be caused by the enhanced light absorption in the visible region originated from Ru-Py. Meanwhile, Ru-Py played an important role in accelerating the separation of photoinduced electron-hole pairs evidenced by the photoluminescence spectra. PEC CO 2 reduction test showed that 84.8 μmol methanol was produced with 63.9% faraday efficiency, 62.6 turnover number (TON) and 45% selectivity at −0.9 V under 8 h irradiation. Furthermore, the non-covalent bonded system only produced 41.3 μmol methanol indicating that the carboxylic covalent linking displayed excellent electron transfer efficiency and methanolization performance. The mechanism investigation revealed that the exposed pyridyl provided the active sites in forming pyridiniumformate intermediates confirmed by the differential UV–vis absorption ( ΔA ) spectrum, which was of great significance in the efficient CO 2 methanolization. The probable reaction pathway for catalytic CO 2 reduction to methanol was also proposed combining the possible intermediates detected by gas chromatography mass spectrometry (GCMS).
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高影响因子
Nanoscale
·
2016
·Vol. 8
·期 38
·16963-16968
·
IF 7.76
Guoqiang Zhang,Wenshuai Jiang,Shixin Hua,Haifeng Zhao,Ligong Zhang,Zaicheng Sun
Defects (Ti3+ or oxygen vacancies) have been demonstrated to promote the charge separation process in TiO2 based photocatalysts. Particularly, the bulk defects within a certain concentration can give a great enhancement for both light absorption and charge separation efficiency. In this report, we explored a one-step molten salts route to synthesize SrTiO3 nanocubes with bulk defects (Ti3+ doped) by using SrCO3 as a Sr source, and TiO2 and Ti powder as Ti sources. The amount of defects can be tuned by changing the molar ratio of Ti/TiO2. The corresponding bandgap of SrTiO3 can be changed from 3.29 to 2.73 eV with the increase of defects. X-ray diffraction and electron microscopy disclose that SrTiO3 is highly crystalline and has a cubic morphology. X-ray photoelectron spectroscopy and electron paramagnetic resonance indicate that the as-prepared SrTiO3 is close to the Ti3+ doped SrTiO3. Surface photovoltage spectroscopy (SPS) and field-induced SPS confirm that Ti3+ doping in the SrTiO3 turns it from an n-type semiconductor to p-type. The SrTiO3 with an optimal amount of defects exhibits highly enhanced photocatalytic performance. An excess amount of defects results in a weak SPS response and photocatalytic performance.
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高影响因子
ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Guodong Zou,Zhiwei Zhang,Jianxin Guo,Baozhong Liu,Qingrui Zhang,Carlos Fernandez,Qiuming Peng
A new MXene/Ag composite was synthesized by direct reduction of a AgNO3 aqueous solution in the presence of MXene (Ti3C2(OH)0.8F1.2). The as-received MXene/Ag composite can be deemed as an excellent anode material for lithium-ion batteries, exhibiting an extraordinary long cycle lifetime with a large capacity at high charge–discharge rates. The results show that Ag self-reduction in MXene solution is related to the existence of low-valence Ti. Reversible capacities of 310 mAh·g–1 at 1 C (theoretical value being ∼320 mAh·g–1), 260 mAh·g–1 at 10 C, and 150 mAh·g–1 at 50 C were achieved. Remarkably, the composite withstands more than 5000 cycles without capacity decay at 1–50 C. The main reasons for the long cycle life with high capacity are relevant to the reduced interface resistance and the occurrence of Ti(II) to Ti(III) during the cycle process.
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高影响因子
Analytical Methods
·
2017
·Vol. 9
·期 30
·4471-4475
·
IF 1.9
L. F. Tian,D. S. Zou,Y. C. Dai,L. L. Wang,W. Gao
Quantification of chromium in V–Cr–Ti ternary alloys, used as candidate structural materials for fusion reactors, is essential in view of its significant effect on the properties of these vanadium-based alloys. Various methods have already been used for the determination of chromium in common alloys, but most of these methods are based on complicated and expensive instruments or suffer from the serious matrix interference of vanadium. In this study, a simple, rapid and accurate spectrophotometric method was developed for the determination of chromium in V–Cr–Ti alloys without any prior separation and chromogenic agent. The alloy samples were dissolved in diluted sulphuric acid and concentrated nitric acid, and chromium was oxidized with persulphate in the presence of Ag(I) ions as a catalyst. After alkalization of the solution with sodium hydrate, greenish-yellow coloured chromate (CrO42−) ions were formed in the alkaline solution and had a maximum absorption peak at 374 nm. Beer's law was obeyed in the range of 0.15–12.0 μg mL−1 Cr(VI) at 374 nm and the molar absorptivity was 4.8 × 103 L mol−1 cm−1. All the variables were studied in order to optimize the analytical conditions. Vanadium and titanium seriously interfered with the determination of Cr(VI) and their interference can be eliminated by addition of ammonium tartrate. The proposed method is simple, fast, accurate and of low cost, and has been satisfactorily used for the determination of chromium in V–Cr–Ti alloys. The results are in good agreement with data given by inductively coupled plasma optical emission spectrometry (ICP-OES) and the relative standard deviation is found to be lower than 0.4%.
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CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
Yina Du,Ji-Xuan Liu,Yifeng Gu,Xin-Gang Wang,Fangfang Xu,Guo-Jun Zhang
Textured and untextured M n+1 AX n compounds, Ti 2 AlC and Ti 3 AlC 2 , namely MAX phases have been synthesized and examined with respect to their corrosion resistance in static supercritical water at 500 °C. The textured ceramics were obtained by hot forging process at high temperatures. Both X-ray diffraction and SEM analysis revealed well alignment of c -plane of MAX phases parallel to the hot-forging surface. Better corrosion resistance on the surface perpendicular to the hot-forged direction was verified by SEM. On the other hand, the side surfaces of the samples showed thick oxidation layers and abundant cracks. The (00 l ) faces consist of strongly bonded Ti 3 C 2 and Ti 2 C layers in Ti 3 AlC 2 and Ti 2 AlC, respectively, hence exhibit higher resistance to water corrosion. On the contrary, the side surfaces where most of weakly bonded interlayers of these hexagonal phases were exposed tend to be easily corroded especially through Al-layers. The corrosion process involved a phase transition of oxidized product, i.e. TiO 2 from anatase to rutile phase, which gave rise to the formation of cracks due to accompanied volume changes.
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Journal of Materiomics
·
2017
·
IF 0
Haiqiang Liu,Hongan Ma,Taichao Su,Yuewen Zhang,Bing Sun,Binwu Liu,Lingjiao Kong,Baomin Liu,Xiaopeng Jia
We present the work about the initiative fabrication of multi-scale hierarchical TiO 2-x by our strategy, combining high pressure and high temperature (HPHT) reactive sintering with appropriate ratio of coarse Ti to nanosized TiO 2 . Ubiquitous lattice defects engineering has also been achieved in our samples by HPHT. The thermoelectric performance was significantly enhanced, and rather low thermal conductivity (1.60 W m −1 K −1 ) for titanium oxide was reported here for TiO 1.76 . Correspondingly, a high dimensionless figure of merit ( zT ) up to 0.33 at 700 °C was realized in it. As far as we know, this value is an enhancement of 43% of the ever best result about nonstoichiometric TiO 2 and the result is also exciting for oxide thermoelectric materials. The moderate power factor, the significantly reduced thermal conductivity and the remarkable synergy between electrical properties and thermal conductivity are responsible for the excellent thermoelectric performance. We develop a facile strategy for preparing multi-scale hierarchical TiO 2-x and its superior ability to optimize thermoelectric performance has been demonstrated here.
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JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Xinru Li,Jiale Li,Zhichao Liu,Can Liu,Yafei Guo,Tianlong Deng
The effective removal of strontium (Sr) from radioactive wastewater is essential for human health and ecological sustainability. However, due to the existence of a large number of coexisting ions, the selective removal of Sr 2+ from it remains a significant challenge. Herein, three novel metal-doped sodium vanadosilicates were developed by structural regulation. It was found that Co-doping can not only significantly reduce the dissolution loss of vanadosilicate (NaVOSi) from the adsorbent in extreme environments by adjusting the orbital energy distribution, energy band structure, bond length, and bond energy of sodium vanadosilicate crystals, but also further enhance the adsorption performance by reducing its zeta potentials and agglomeration phenomenon. The maximum adsorption capacity of the developed adsorbent (Co-NaVOSi) was up to 319.10 mg·g −1 within 5 min. When applied to Sr 2+ removal from simulated wastewater, the distribution coefficients of Sr 2+ reached 2943.15 mL·g −1 , and the separation coefficients between Sr 2+ and coexisting ions were above 64. DFT calculations further revealed the highly selective removal mechanism of Sr 2+ from wastewater. In addition, NaNO 3 was proved to be an efficient eluent. The excellent properties above make NaVOSi an excellent candidate for effectively removing Sr 2+ from wastewater.
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高影响因子
ACS Nano
·
2017
·
IF 13.942
Guodong Zou,Qingrui Zhang,Carlos Fernandez,Gang Huang,Jianyu Huang,Qiuming Peng
Rational design of heterogeneous electrode materials with hierarchical architecture is a potential approach to significantly improve their energy densities. Herein, we report a tailored microwave-assisted synthetic strategy to create heterogeneous hierarchical Ti3SiC2@C-containing Na2Ti7O15 (MAX@C-NTO) composites as potential anode materials for high-performance sodium storage in a wide temperature range from 25 to 80 °C. This composite delivers first reversible capacities of 230 mAh g–1 at 200 mA g–1 and 149 mAh g–1 at 3000 mA g–1 at 25 °C. A high capacity of ∼93 mAh g–1 without any apparent decay even after more than 10 000 cycles is obtained at an ultrahigh current density of 10 000 mA g–1. Moreover, both a high reversible capacity and an ultralong durable stability are achieved below 60 °C for the same composites, wherein a 75.2% capacity retention (∼120 mAh g–1 at 10 000 mA g–1) is achieved after 3000 cycles at 60 °C. To the best of our knowledge, both the sodium storage performances and the temperature tolerances outperform those of all the Ti-based sodium storage materials reported so far. The superior sodium storage performances of the as-synthesized composites are attributed to the heterogeneous core–shell architecture, which not only provides fast kinetics by high pseudocapacitance but also prolongs cycling life by preventing particle agglomeration and facilitates the transportation of electrons and sodium ions by large micro/mesopore structure.
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高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2017
·
IF 3.454
Y.L. Zhuang,T.S. Lin,S.J. Wang,P. He,D.P. Sekulic,D.C. Jia
The Ti 22 Si 78 (wt.%) braze was used to bond porous BN/Si 3 N 4 ceramic. The results revealed that the joint strength was low. In order to improve the joint strength, a carbon coated modification of the porous BN/Si 3 N 4 substrate, achieved by the pyrolysis of phenol-formaldehyde resin was suggested. The thickness of carbon layer was controlled by the volume ratio of phenol-formaldehyde resin and methyl alcohol (R/M). The effect of the carbon layer on the microstructure and mechanical properties of the joint was examined. It was established that the maximum joint strength was achieved at the level of 80 MPa (as opposed to the uncoated joint with only 30 MPa) when R/M was 1:2, at the given brazing temperature. The improvement of the joint strength is attributed mainly to the formation of a SiC infiltration reaction layer, a significant population of SiC nanowires, as well as TiN 0.7 C 0.3 and TiB 2 particles.
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MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
·
2025
·
IF 7
Yu He,Shengwei Xin,Baoru Sun,Xuecheng Cai,Yapeng Lin,Lingwei Kong,Xun Shen,Congcong Du,Xiaoyuan Yuan,Kangkang Wen,Tongde Shen
Metals are often soft while ceramics are often hard. To make metals as hard as ceramics has been long-awaited in metals and ceramics communities. In this study, bulk nanocrystalline (NC) tungsten-1 wt% yttrium-0.7 wt% titanium (WYT) was fabricated via mechanical alloying followed by high-temperature/high-pressure sintering. The high pressure directly inhibits grain growth by suppressing atomic diffusion and indirectly inhibits grain growth by lowering sintering temperature, enabling the synthesis of dense NC WYT bulks with an average grain size of ∼ 9.0 nm. The high temperature causes annealing- and segregation-induced structural relaxation of grain boundaries (GBs) in sintered bulk NC WYT, resulting in GBs with a small excess volume of only ∼ 0.005 nm, one fifth that of bulk NC tungsten. The small grain size and the relaxed GBs in the bulk NC WYT make it hard for GBs to emit dislocations, resulting in extremely high hardness of 23.2 ± 0.3 GPa, yield strength of 9.4 ± 0.3 GPa, and ultimate compressive strength of 13.1 ± 1.1 GPa. The hardness of metallic bulk NC WYT is comparable to that of ceramic tungsten carbide (WC) whereas the wear rate of bulk NC WYT is even lower than that of WC. The structure-relaxed GBs lower the thermodynamic driving force for grain growth and result in an extremely high thermal stability - no grain growth occurs in bulk NC WYT annealed at a high temperature of 1500 °C, which is above the recrystallization temperature of tungsten. The present strategy - multifunctional treatments of NC alloy powders by high-temperature/high-pressure - provides a huge potential to manufacture dense bulk NC materials with exceptional mechanical property and thermal stability for practical applications.
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JOURNAL OF ELECTRONIC MATERIALS
·
2017
·Vol. 47
·期 6
·3248-3253
·
IF 1.579
Chen Jun-Liang,Liu Chengyan,Miao Lei,Gao Jie,Zheng Yan-yan,Wang Xiaoyang,Lu Jiacai,Shu Mingzheng
With excellent high-temperature stability (up to 1000 K) and favorable electrical properties for thermoelectric application, TiNiSn-based half-Heusler (HH) alloys are expected to be promising thermoelectric materials for the recovery of waste heat in the temperature ranging from 700 K to 900 K. However, their thermal conductivity is always relatively high (5–10 W/mK), making it difficult to further enhance their thermoelectric figure-of-merit ( ZT ). In the past decade, introducing nano-scale secondary phases into the HH alloy matrix has been proven to be feasible for optimizing the thermoelectric performance of TiNiSn. In this study, a series of TiNiSn-based alloys have been successfully synthesized by a simple solid-state reaction. The content and composition of the heterogeneous phase (TiNi 2 Sn and Sn) is accurately regulated and, as a result, the thermal conductivity successfully reduced from 4.9 W m −1 K −1 to 3.0 Wm −1 K −1 (750 K) due to multi-scale phonon scattering. Consequently, a ZT value of 0.49 is achieved at 750 K in our TiNiSn-based thermoelectric materials. Furthermore, the thermal stability of TiNiSn alloys is enhanced through reducing the Sn substance phase.
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Journal of Advanced Ceramics
·
2017
·Vol. 7
·期 1
·41-49
·
IF 1.198
Peng Le,Zhang Kuibao,He Zongsheng,Yin Dan,Xue Jiali,Xu Chen,Zhang Haibin
In this research, Zr-doped Gd 2 Ti 2 O 7 pyrochlores, with the composition of Gd 2 (Ti 1- x Zr
x
) 2 O 7 , were firstly synthesized by self-propagating high-temperature synthesis plus quick pressing (SHS/QP) using CuO as the oxidant and Ti as the reductant. To improve the radiation resistance of titanate–pyrochlore, up to 35 at% Zr was incorporated to substitute the Ti site of Gd 2 Ti 2 O 7 pyrochlore (Gd 2 (Ti 0.75 Zr 0.35 ) 2 O 7 ). XRD and SEM microstructural characterizations showed the formation of a composite ceramic with the major pyrochlore phase and the minor Cu phase. The generated temperature of samples decreased from 1702 to 1011°C with increasing Zr content. The effects of sintering temperature and pressure time on phase composition and microstructure were systematically studied. Besides, the influence of thermal transmission on the whole combustion process was also explored. The pyrochlore-based waste form possessed high bulk density of 6.25 g/cm 3 and Vickers hardness of 10.81 GPa. The MCC-1 leaching test showed the normalized elemental leaching rates (42 d) of Cu, Gd, and Zr are 1.27×10 -2 , 1.33×10 -3 , and 8.44×10 -7 g·m -2 ·d -1 , respectively.
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