Journal of Materials Chemistry C
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2018
·Vol. 6
·期 47
·13013-13022
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IF 5.976
Dong Lu,Yiping Tang,Jinwei Gao,Qianming Wang
In contrast to conventional nanomaterials or organic dyes, carbon dots possess a variety of appealing properties including chemical inertness and easy manipulation and they can be dispersed in water. Herein, the use of a concentrated solar irradiation sintering strategy for the rapid and efficient assembly of carbon dots (CDs) has been reported for the first time. This novel alternative pathway effectively uses a renewable source and the process is feasible and environmentally sustainable. Three kinds of CDs were obtained, which demonstrate blue, green and red luminescence. Highly efficient blue-emitting CDs with quantum yield as high as 81% have been realized. The blue and red carbon dots give rise to excitation-independent emission peaks at 443 and 592 nm, respectively; however, the green CDs feature a continuous shift and the evolution of emission curves varies from 480 to 538 nm. By regulating the composition and ratios of these tri-color carbon dots, the emission band generates peaks from blue to red light, which cover almost the entire visible light range. Upon a single ultra-violet excitation at 365 nm, a white-light emission with CIE coordinates of (0.28, 0.33) was detected and the signal was very close to pure white light (0.33, 0.33). This study introduces a new method for fabricating low-cost nanoparticles as potential phosphors for light-emitting uses.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2018
·
IF 3.779
Abdul Basit,Junyou Yang,Qinghui Jiang,Zhiwei Zhou,Jiwu Xin,Xin Li,Sihui Li
Here, the intellectual challenges for thermoelectric materials revolves around the strategy of point defect engineering to regulate the electrical and thermal transport nature of Mn 1.06- x Sn x Te ( x = 0, 0.03, 0.035, 0.04, 0.045) materials. The power factor increases with substitution of Sn into the lattice of Mn 1.06 Te leading to enhance the carrier concentrations due to reduction of the band gap. Meanwhile, the thermal conductivity has also been remarkably reduced due to diverse phonon scattering and mass fluctuation by Sn substitution. As a result, a maximum ZT ∼0.93 for Mn 1.06- x Sn x Te ( x = 0.04) sample has been achieved at 873 K, which increases by 56% in comparison with the un-doped sample.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Dongyang Wang,Xiao Zhang,Yong Yu,Lin Xie,Jinfeng Wang,Guangtao Wang,Jiaqing He,Yuling Zhou,Qiantao Pang,Jianwei Shao,Li-Dong Zhao
In this work, we report that the high performance of SnTe could be realized by enhancing electrical transport properties (power factor) and reducing thermal conductivity through stepwisely introducing elements of Sb, In and Se. We found that Sb and In co-doping can enhance Seebeck coefficients in the broad temperature range via optimizing carrier density and introducing resonant state, respectively. Moreover, nanostructures could be formed when the Sb content beyond the solubility limit in SnTe matrix, which coupled with point defects from In and Se alloying result in a very low (lattice) thermal conductivity through the enhanced phonon scattering from defects and grain boundaries. A peak ZT ∼1.0 at 923 K can be achieved with the enhanced power factor and reduced thermal conductivity. Accordingly, the average ZT value increases from ∼0.20 for undoped SnTe to ∼ 0.60 for multiple-doped SnTe (Sn 0.823 Sb 0.17 In 0.007 Te 0.98 Se 0.02 ) over 300–923 K, generating a high calculated conversion efficiency ∼ 11%. Present results indicate the high performance of SnTe can be obtained through stepwisely optimizing strategy in both electrical and thermal transport properties.
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JOURNAL OF THE CERAMIC SOCIETY OF JAPAN
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2018
·Vol. 126
·期 11
·900-905
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IF 0.887
Shuai LU,Xiaoqiang LI,Youfu ZHOU,Wentao XU,Junrong LING,Wei PAN
TiB2/Ti2AlN composites with different proportions were successfully fabricated through solid state reaction of Ti/Al/AlN/BN powders and subsequent hot pressing sintering. The reaction mechanism, microstructures and mechanical properties of the composites were investigated. The Vickers hardness of the samples ascended with increases in the TiB2 content and reached the highest value of 11.32 ± 0.12 GPa at a TiB2/Ti2AlN mole ratio of 1:2 (M2T1). TiB2/Ti2AlN composites with a mole ratio of 1:3 (M3T1) and 1:4 (M4T1) exhibited the maximum flexural strength of 497 ± 15 MPa and the highest fracture toughness of 9.52 ± 0.14 MPa·m1/2, respectively, which are 1.3 times and 1.8 times that of pure Ti2AlN (MT0) ceramic.
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Materials
·
2019
·Vol. 12
·期 9
·1501
·
IF 2.972
Hongdan Zhang,Ludan Zhu,Jun Cheng,Long Chen,Chuanqi Liu,Shuanglong Yuan
In recent years, all-inorganic lead-halide perovskites have received extensive attention due to their many advantages, but their poor stability and high toxicity are two major problems. In this paper, a low toxicity and stable Cs2SnCl6double perovskite crystals were prepared by aqueous phase precipitation method using SnCl2as precursor. By the XRD, ICP-AES, XPS, photoluminescence and absorption spectra, the fluorescence decay curve, the structure and photoluminescence characteristics of Ce3+-doped and undoped samples have been investigated in detail. The results show that the photoluminescence originates from defects. [SnSn4+2++VCl] defect complex in the crystal is formed by Sn2+substituting Sn4+. The number of defects formed by Sn2+in the crystal decreases with Ce3+content increases. Within a certain number of defects, the crystal luminescence is enhanced with the number of [SnSn4+2++VCl] decreased. When Ce3+is incorporated into the crystals, the defects of [Ce3+Sn4++VCl] and [SnSn4+2++VCl] were formed and the crystal show the strongest emission. This provides a route to enhance the photoluminescence of Cs2SnCl6double perovskite crystals.Keywords:lead-free perovskite;Cs2SnCl6;doping;photoluminescence
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Journal of Materials Chemistry C
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2018
·Vol. 7
·期 2
·247-255
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IF 5.976
Chunyan Jiang,Mikhail G. Brik,Alok M. Srivastava,Lihua Li,Mingying Peng
Mn4+ doped fluoride phosphors have attracted tremendous attention in the solid-state lighting field due to the outstanding feature of efficient narrow band red emission. However, poor resistance against moisture-induced luminescence quenching is a recognized obstacle for realizing their wider commercial use. Herein, we design and fabricate a highly stable red phosphor based on previously unnoticed Rb2SnF6:Mn4+, which, estimated by the single crystal X-ray diffraction data, crystallizes in the trigonal space group Pm1 with the lattice parameters a = b = 6.0323(12) Å, c = 4.7880(8) Å, and V = 150.89(7) Å3. The Rb2SnF6:Mn4+ as expected exhibits highly efficient red emission upon excitation by UV and blue light. Significantly, the poor water resistance is conquered by constructing a protective deactivated layer with surface reduction of Mn4+. A treatment solution with appropriate reducing ability is emphasized to obtain Rb2SnF6:Mn4+ with simultaneous high brightness and water resistance. The results show that the low concentration of H2C2O4 solution treated Rb2SnF6:Mn4+ preserves a bright red-emitting color analogous to its initial color and >95% of its initial emission intensity when immersing in water at room temperature (RT) and in boiling water for 3 h. Lastly, by employing H2C2O4 treated Rb2SnF6:Mn4+ as a red phosphor, a high quality WLED with a CRI of 90, CCT of 3936 K and luminous efficacy of 106.24 lm W−1 is fabricated. This work not only experimentally fabricates a new efficient and stable Rb2SnF6:Mn4+ phosphor that can be used for high performance warm WLEDs but also provides a deep insight into how to well address moisture-induced Mn4+ luminescence quenching through appropriate reduction of Mn4+, opening up new opportunities for future solid-state lighting purposes.
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Materials Today Physics
·
2018
·
IF 0
Y. Zhou,H. Wu,D. Wang,L. Fu,Y. Zhang,J. He,S.J. Pennycook,L.-D. Zhao
The ternary diamond-like compound Cu 2 SnSe 3 is a potential thermoelectric material . Its Cu-Se conducting network leaves Sn as a likely doping site to optimize the carrier concentration without much deterioration to the carrier mobility . Thus, the precise determination on the intricate phase structures of Cu 2 SnSe 3 is critical. Here, we first use the atomically resolved scanning transmission electron microscopy and reveal an unusual phase coexistence (monoclinic and orthorhombic phases) in Ag-doped Cu 2 SnSe 3 . Owing to coexisting phases and the order–disorder transition in the orthorhombic phase, the Ag-doped Cu 2 SnSe 3 shows an unusual three-stage behavior in its temperature-dependent electrical transport properties and achieves record high power factors in this system. The observed three-stage behavior due to the phase coexistence is supported by the first principle calculations, Hall measurements, and optical diffuse reflectance measurements . To fully understand the band structures and the coherent interface between these coexisting phases, a band contact model is proposed that could well explain the three-stage electrical transport behavior. Moreover, the phase coexistence is observed at the nanoscale regime, thus providing a high density of phase boundaries. Such coexisting nanophases play an important role in lowering the lattice thermal conductivity . As a result, the ZT value obtained in Cu 2 Sn 0.93 Ag 0.07 Se 3 is double that of undoped Cu 2 SnSe 3 .
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ELECTROANALYSIS
·
2018
·Vol. 30
·期 11
·2768-2773
·
IF 2.851
Xin Feng,Xiaomei Dong,Qingcheng Zhang,Cuixia Cui,JingJing Zhang,Zhen Chen,Changmi Wu,Huile Jin,Shun Wang,Jichang Wang
In this study carbon materials with a hierarchical pore structure have been fabricated through a scalable and template free solvothermal method in the presence of metal catalysts, where the presence of metal catalysts was found to be essential for the initial polymerization process. The as-prepared carbon contained trace amounts of metal residues and exhibited highly efficient catalytic activity toward the oxygen reduction reaction (ORR). Among all the metal catalysts studied, cobalt containing porous carbon exhibited the highest ORR electrocatalytic activity with great tolerance to methanol crossover and excellent long-term cycling stability, outperforming the commercial 30 % ( w / w ) Pt/C catalysts. The great performance may be contributed to the unique porous structure, the large specific surface area of cobalt-doped carbon and chemical activity of cobalt. The result provides useful guidance for the development of carbon-based electrocatalysts.
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ACS Applied Materials & Interfaces
·
2014
·
IF 5.9
Yanchun Yang,Gang Wang,Wangen Zhao,Qingwen Tian,Lijian Huang,Daocheng Pan
Solution deposition approaches play an important role in reducing the manufacturing cost of Cu2ZnSnSe4 (CZTSe) thin film solar cells. Here, we present a novel precursor-based solution approach to fabricate highly efficient CZTSe solar cells. In this approach, low-cost elemental Cu, Zn, Sn, and Se powders were simultaneously dissolved in the solution of thioglycolic acid and ethanolamine, forming a homogeneous CZTSe precursor solution to deposit CZTSe nanocrystal thin films. Based on high-quality CZTSe absorber layer, pure selenide CZTSe solar cell with a photoelectric conversion efficiency of 8.02% has been achieved without antireflection coating.
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ACS Applied Materials & Interfaces
·
2013
·
IF 5.008
Mingxi Chen,Congcong Zhang,Lingzhi Li,Yu Liu,Xichuan Li,Xiaoyang Xu,Fengling Xia,Wei Wang,Jianping Gao
A facile approach to prepare SnO2/rGO (reduced graphene oxide) hybrid nanoparticles by a direct redox reaction between graphene oxide (GO) and tin powder was developed. Since no acid was used, it is an environmentally friendly green method. The SnO2/rGO hybrid nanoparticles were characterized by ultraviolet–visible spectroscopy, Raman spectroscopy, thermogravimetric analysis, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The microstructure of the SnO2/rGO was observed with scanning electron microscopy and transmission electron microscopy. The tin powder efficiently reduced GO to rGO, and the Sn was transformed to SnO2 nanoparticles (∼45 nm) that were evenly distributed on the rGO sheets. The SnO2/rGO hybrid nanoparticles were then coated on an interdigital electrode to fabricate a humidity sensor, which have an especially good linear impedance response from 11% to 85% relative humidity.
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Scientific Reports
·
2014
·Vol. 4
·期 1
·1-9
·
IF 5.078
Zhong Jie,Xia Zhe,Luo Miao,Zhao Juan,Chen Jie,Wang Liang,Liu Xinsheng,Xue Ding-Jiang,Cheng Yi-Bing,Song Haisheng,Tang Jiang
To obtain high photovoltaic performances for the emerging copper zinc tin sulfide/selenide (CZTSSe) thin film solar cells, much effort has deservedly been placed on CZTSSe phase purification and CZTSSe grain size enhancement. Another highly crucial but less explored factor for device performance is the elemental constitution of CZTSSe surface, which is at the heart of p-n junction where major photogenerated carriers generate and separate. In this work we demonstrate that, despite the well-built phase and large grained films are observed by common phases and morphology characterization (XRD, Raman and SEM), prominent device efficiency variations from short circuited to 6.4% are obtained. Insight study highlights that the surface (0–250 nm) compositions variation results in different bulk defect depths and doping densities in the depletion zone. We propose that suitable sulfurization (at ~10 kPa sulfur pressure) drives optimization of surface constitution by managing the Cu, Zn and Sn diffusion and surface reaction. Therefore, our study reveals that the balance of elemental diffusion and interface reactions is the key to tuning the surface quality CZTSSe film and thus the performance of as resulted devices.
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JOURNAL OF MOLECULAR LIQUIDS
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2014
·
IF 2.083
Jian-Rong Li,Xu Wang,Baoling Yuan,Ming-Lai Fu
The layered chalcogenide, K 2x Mn x Sn 3− x S 6 (x = 0.5 –0.95), which exhibited excellent adsorption properties for removal of Cu 2 + from aqueous solution, was synthesized hydrothermally. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectrometer (EDS) were used to characterize the crystal structure, chemical composition and micro-morphologies of KMS-1 before and after adsorption. Cu 2 + can covalently bond with sulfur atoms after it exchanged with K + . The interlayer spacing of KMS-1 was changed from 0.851 nm to 0.592 nm after adsorption. The sizes of KMS-1 crystalline after adsorption changed to smaller. The effects of pH, reaction time, initial concentration, reaction temperature and coexisting ions on the adsorption of Cu 2 + by KMS-1 were studied. The pH was found to be a slight factor determining adsorption capacity at pH from 3 to 6. Kinetic data were fitted well to a pseudo-second-order kinetic model and the rate controlling steps were external film diffusion and intraparticle diffusion at different temperatures. The activation energy for the adsorption process was estimated to be 45.15 kJ/mol. The maximum adsorption capacity of KMS-1 was 164.7, 155.6 and 152.7 mg/g at a temperature of 10, 25 and 40 °C, respectively. The Langmuir adsorption isotherm was used to fit the adsorption equilibrium process. The alkaline and alkaline earth metal ions had slight effect on the removal efficiency of Cu 2 + and the degree of inhibition followed the order: Ca 2 + > Mg 2 + > Na + . The heavy metal ions had great effect on the removal efficiency of Cu 2 + and the degree of inhibition followed the order: Cd 2 + > Pb 2 + > Zn 2 + > Ni 2 + . The adsorbed KMS-1 can be considered as an excellent permanent waste storage without the risk of leaching of Cu 2 + .
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