ULTRASONICS SONOCHEMISTRY
·
2021
·
IF 7.491
Youwen Tian,Wei Luo,Yedan Wang,Yun Yu,Wanzhen Huang,Haodong Tang,Yifan Zheng,Zongjian Liu
Although the traditional Stoˇber process-based methods are widely used for encapsulation of metal nanoparticles in SiO 2 , these time-consuming methods are not effective for coating metal microparticles with a uniform SiO 2 layer of desired thickness. Herein, an ultrasound-assisted, interface-confined sol–gel method is proposed for fast encapsulation of metal microparticles in SiO 2 , and the encapsulation of Sn microparticles is chosen as an example to illustrate its feasibility. The proposed method involves covering metal microparticles with liquid films that contain water, alcohol, surfactant (Span-80) and catalyst (NH 4 F) and then ultrasonically dispersing these particles into cyclohexane, where tetraethylorthosilicate (TEOS) is added. To ensure the hydrolysis-condensation reactions of TEOS occurring at the particle-cyclohexane interface so that the formed SiO 2 is coated on the particles, the microparticles should be well dispersed into cyclohexane with the liquid films being not broken away from their surfaces. It is found that the assistance of probe sonication and the addition of surfactant are crucial to achievement of a good dispersion of metal microparticles in cyclohexane. And using high-viscosity alcohol (namely glycerol), controlling the volume ratio of water to alcohol and the amount of water, and choosing a suitable ultrasonic power are essential for preventing the formation of free SiO 2 (namely SiO 2 that is not coated on the particles), which is a result that the liquid films escape from the particle surfaces under ultrasonic cavitation. Our results have also revealed that the thickness of SiO 2 layer can be adjusted by changing the reaction time or the total amount of water. In particular, the thickness of SiO 2 layer can be easily raised by simply repeating the encapsulation procedure. Compared with the traditional Stoˇber process-based methods, the proposed method is time-saving (reaction time: about 30 min vs. more than 12 h) and extremely effective for coating microparticles with a continuous, uniform SiO 2 layer of desired thickness.
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高影响因子
ADVANCED MATERIALS
·
2021
·Vol. 33
·期 11
·2004711
·
IF 30.849
Yuxuan Liu,Renzong Hu,Dechao Zhang,Jiangwen Liu,Fang Liu,Jie Cui,Zuopeng Lin,Jinsong Wu,Min Zhu
To achieve high ionic conductivity for solid electrolyte, an artificial Li-rich interface layer of about 60 nm thick has been constructed in polymer-based poly(ethylene oxide)-lithium bis(trifluoromethanesulfonyl)imide composite solid electrolyte (briefly noted as PEO m ) by adding Li-based alloys. As revealed by high-resolution transmission electron microscopy and electron energy loss spectroscopy, an artificial interface layer of amorphous feature is created around the Li-based alloy particles with the gradient distribution of Li across it. Electrochemical analysis and theoretical modeling demonstrate that the interface layer provides fast ion transport path and plays a key role in achieving high and stable ionic conductivity for PEO m -Li 21 Si 5 composite solid electrolyte. The PEO m -5%Li 21 Si 5 composite electrolyte exhibits an ionic conductivity of 3.9 × 10 –5 S cm −1 at 30 ° C and 5.6 × 10 −4 S cm −1 at 45 ° C. The LiFePO 4 | PEO m -5%Li 21 Si 5 | Li all-solid-state batteries could maintain a stable capacity of 129.2 mA h g −1 at 0.2 C and 30 ° C after 100 cycles, and 111.3 mA h g −1 after 200 cycles at 0.5 C and 45 ° C, demonstrating excellent cycling stability and high-rate capability.
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高影响因子
ACS Applied Materials & Interfaces
·
2021
·
IF 9.229
Yuechao Zhao,Xiangyun Zhao,Dongxing Kou,Wenhui Zhou,Zhengji Zhou,Shengjie Yuan,Yafang Qi,Zhi Zheng,Sixin Wu
Although the traditional Cu-poor architecture addresses many limitations for Cu2ZnSn(S,Se)4 solar cells, its further development still encounters a bottleneck in terms of efficiency, primarily arising from the inferior charge transport within the quasineutral region and enlarged recombination at back contact. On the contrary, the electrical benign kesterite compound with higher Cu content may compensate for these shortages, but it will degrade device performance more pronouncedly at front contact because of the Fermi level pinning and more electric shunts. Based on the electric disparities on their independent side, in this work, we propose a new status of Cu component by exploring a large grain/fine grain/large grain trilayer architecture with higher Cu content near back contact and lower Cu content near front contact. The benefits of this bottom Cu-higher strategy are that it imposes a concentration gradient to drive carrier diffusion toward front contact and decreases the valence band edge offset in the rear of the device to aid in hole extraction. Also, it maintains the Cu-poor architecture at the near surface to facilitate hole quasi-Fermi level splitting. In return, the local Cu component engineering-mediated electric advances contribute to the highest efficiency of 12.54% for kesterite solar cells using amine–thiol solution systems so far.
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高影响因子
Materials
·
2020
·Vol. 13
·期 23
·5356
·
IF 3.057
Weihua Chen,Jiancheng Tang,Xinghao Lin,Yunlong Ai,Nan Ye
In the present study, high-purity ternary-phase nitride (Ti2AlN) powders were synthesized through microwave sintering using TiH2, Al, and TiN powders as raw materials. X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were adopted to characterize the as-prepared powders. It was found that the Ti2AlN powder prepared by the microwave sintering of the 1TiH2/1.15Al/1TiN mixture at 1250 °C for 30 min manifested great purity (96.68%) with uniform grain size distribution. The formation mechanism of Ti2AlN occurred in four stages. The solid-phase reaction of Ti/Al and Ti/TiN took place below the melting point of aluminum and formed Ti2Al and TiN0.5phases, which were the main intermediates in Ti2AlN formation. Therefore, the present work puts forward a favorable method for the preparation of high-purity Ti2AlN powders.Keywords:MAX-phase Ti2AlN;microwave;synthesis;high-purity powder
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高影响因子
Journal of Materials Chemistry A
·
2020
·Vol. 9
·期 1
·413-422
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IF 11.301
Xiaohuan Chang,Junjie Fu,Dongxing Kou,Wenhui Zhou,Zhengji Zhou,Shengjie Yuan,Yafang Qi,Zhi Zheng,Sixin Wu
The introduction of alkali metal (AM) post-deposition treatment (PDT) has led to the consecutive breakthrough of world record efficiencies for Cu(In,Ga)Se2 photovoltaics. However, for the derivative Cu2SnZn(S,Se)4 (CZTSSe) solar cells, the corresponding verdict seems partially unjustified due to the difference in defect chemical environment and phase structure, and the most effective incorporation means of AMs is still a mystery. In this work, for the first time, we developed a dual AM synergistic incorporation strategy combining light and heavy AMs by post-depositing CsF after NaF-PDT to improve the efficiency of CZTSSe solar cells. The relevant microscopic-electrical advantages with regard to the different roles of NaF and CsF PDT are discussed in more detail. It was found that the Na atoms are randomly dispersed both in the grain interior (GI) and grain boundaries (GBs), significantly increasing the acceptor concentration and passivating the deep level defects to enhance the Voc. In contrast, the Cs atoms are mainly segregated at the GBs, primarily increasing the potential of the GBs and improving the FF. The prominent electric benefits of Cs at the GBs and Na in the GI finally increase the device efficiency from 10.12% to 12.16%. Our findings solve the difficulty in obtaining the available Voc and FF for future high efficiency research and should serve as a basis for the in-depth understanding of AM-PDT in kesterite photovoltaics.
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高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Lu Yue,Maleraju Jayapal,Xinli Cheng,Tingting Zhang,Junfeng Chen,Xiaoyan Ma,Xin Dai,Haiqin Lu,Rongfeng Guan,WenHui Zhang
High theoretical capacity and low discharge platforms of Sn and Sb-based materials are an auspicious anode material for sodium ion batteries. Although, their large volume change before and after sodium insertion during cycling leads to unstable electrode structure and poor cycle performance. In view of the above, a thermo chemical strategy by a simple one-pot for producing 3–6 nm diameter homogeneously dispersed Sn/SnSb nanoparticles on a nitrogen-doped graphene sheet with a large-scale and low-cost feature for high performance sodium ion battery is reported. Highly dispersed nano Sn-SnSb alloy/graphene composite electrode not only had good stress adaptability and good integrity protection to prevent agglomeration and polarization during cycling, and also provided the rapid Na + diffusion and electronic transfer channels, thus showing high rate and ultra-stable cycle performance. The as-prepared electrode could maintain the super stable reversible capacities of 251.8, 146.2 and 60.2 mAh g −1 at 1, 4 and 10 A g −1 over 1000 cycles, respectively.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Xiangju Chen,Yang Hong,Xiaoli Ge,Caixia Li,Xianguang Miao,Peng Wang,Zhiwei Zhang,Longwei Yin
Taking advantage of nano-sized active materials, doping and self-supporting, Se-doped Bi 2 S 3 /3D carbon foam (Bi 2 S 3-x Se x /CF) is synthesized through a pyrolysing-hydrothermal-heating three-steps process. The as-synthesized Bi 2 S 3-x Se x /CF hybrid exhibits a significant improvement in electrochemical performance, showing a high specific capacity of 441.8 mAh g −1 after 100 cycles with the coulombic efficiency approximating to 100%. The special nanoneedle-like structure of Bi 2 S 3 makes for shortening ion transmission distance, minishing the mechanical stress and thus improving the electrochemical performance. And the introduction of Se can enhance the specific capacity, cycling stability and rate performance by improving of electronic conductivity and forming Se-contained inactive phase during alloying process. Furthermore, the self-supporting electrode is beneficial to simplify preparation process and reduce the loss of volume energy density . The strategy presented in this paper to improve the electrochemical performance of secondary ions battery can be also applied to other novel electrodes materials.
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高影响因子
Advanced Science
·
2020
·Vol. 7
·期 11
·1903493
·
IF 15.84
Sihui Li,Jiwu Xin,Abdul Basit,Qiang Long,Suwei Li,Qinghui Jiang,Yubo Luo,Junyou Yang
Lead-free chalcogenide SnTe has been demonstrated to be an efficient medium temperature thermoelectric (TE) material. However, high intrinsic Sn vacancies as well as high thermal conductivity devalue its performance. Here, β-Zn 4 Sb 3 is incorporated into the SnTe matrix to regulate the thermoelectric performance of SnTe. Sequential in situ reactions take place between the β-Zn 4 Sb 3 additive and SnTe matrix, and an interesting “core–shell” microstructure (Sb@ZnTe) is obtained; the composition of SnTe matrix is also tuned and thus Sn vacancies are compensated effectively. Benefitting from the synergistic effect of the in situ reactions, an ultralow κ lat ≈0.48 W m −1 K −1 at 873 K is obtained and the carrier concentrations and electrical properties are also improved successfully. Finally, a maximum ZT ≈1.32, which increases by ≈220% over the pristine SnTe, is achieved in the SnTe-1.5% β-Zn 4 Sb 3 sample at 873 K. This work provides a new strategy to regulate the TE performance of SnTe and also offers a new insight to other related thermoelectric materials.
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高影响因子
Journal of Energy Chemistry
·
2020
·
IF 7.216
Xiao Liu,Peijie Fan,Liangping Xiao,Jian Weng,Qingchi Xu,Jun Xu
The generation of green hydrogen (H 2 ) energy is of great significance to solve worldwide energy and environmental issues. Reduced Ti based photocatalyst has recently attracted intensive attention due to its excellent photocatalytic activity, while the synthesis of reduced Ti based photocatalysts with high stability is still a great challenge. Here, we report a facile method for synthesis of reduced Ti metal organic frameworks (small amounts of Pt incorporated) encapsulated BP (BP/R-Ti-MOFs/Pt) hybrid nanomaterial with enhanced photocatalytic activity. The strong interaction between Ti and P reduces the valence state of the binding Ti 4+ on the BP surface, forming abundant reduced Ti 4+ within R-Ti-MOFs/BP. Such reduced Ti 4+ render R-Ti-MOFs/BP efficient charge transfer and excellent light absorption capability, thus promote the photocatalytic H 2 production efficiency. Furthermore, the Ti-P interaction stabilizes both reduced Ti 4+ and BP during the photocatalytic reaction, which greatly enhanced the stability of the obtained BP/R-Ti-MOFs/Pt photocatalyst.
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高影响因子
Materials Today Energy
·
2020
·
IF 5.604
Jun Xu,Rixin Wang,Xing Chen,Ru Zhou,Junjun Zhang
Copper-containing bimetallic sulfides are regarded as an emerging low-cost catalyst for electrocatalytic hydrogen generation. In this work, we report for the first time the ternary Cu 2 SnS 3 (CTS) nanocrystals anchored reduced graphene oxide (rGO) nanosheets (CTS@rGO) as a superior electrocatalyst for efficient hydrogen generation. The CTS nanocrystals with 5–10 nm are much homogeneously distributed on the surface of rGO nanosheets. In the CTS@rGO composite, the rGO works as a robust scaffold that can effectively suppress aggregation of the CTS nanocrystals and ensure more exposed active sites on CTS surfaces. Furthermore, the conductive rGO is beneficial to fast charge transfer. Therefore, the CTS@rGO catalyst possesses a large electrocatalytic active surface area and a small charge transfer resistance. As a result, the CTS@rGO exhibits significantly enhanced catalytic activity for hydrogen evolution reaction (HER) in both the acid and alkaline electrolytes in comparison with the pristine CTS nanocrystals. The CTS@rGO delivers a striking catalytic kinetic metrics of a small Tafel slope of 54 mV dec −1 , a low overpotential of 252 mV at a current density of 10 mA cm −2 , long operation stability of 4 day in the acid electrolyte.
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JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2020
·Vol. 35
·期 2
·272-279
·
IF 0.64
Li Zhi,Shen Wenjian,Zhao Juan,Ying Hangkai,Wu Zhengli,Liu Yifan,Li Wangnan,Ku Zhiliang,Peng Yong,Huang Fuzhi,Cheng Yibing,Zhong Jie,Fu Zhengyi
A novel aqueous Sn-S complex solution was applied as precursor to fabricate SnO 2 electron selective layers (ESLs) for the hybrid perovskite solar cells (PSCs). The tin and sulfur powder were directly dissolved in a (NH 4 ) 2 S water solution to form Sn-S precursor. After depositon and annealing, the SnO 2 film was formed, presenting as a low cost and enviromental friendly method for preparation of ESL. The films showed excellent transmittance at visible wavelength range. Moreover, the method exhibited high compatibility for doping using Cu, Cd, Li, and Zn elements. Zn doping (0.05 M) in the as-prepared SnO 2 ESL significantly improved perovskite solar cells (PSCs) performance. The highest PCE of 13.17% was achived with 15% enhancement compared to that of undoped SnO 2 ESL samples. TiCl 4 modifications on SnO 2 film improved photovoltaic performance to 14.45%, but resulted in the poor long-term stability, around 80% more degredation than that of PSCs based on Zn-doped SnO 2 films.
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高影响因子
GREEN CHEMISTRY
·
2020
·Vol. 22
·期 11
·3597-3607
·
IF 9.48
Hai-Qin Xiao,Wen-Hui Zhou,Dong-Xing Kou,Zheng-Ji Zhou,Yue-Na Meng,Ya-Fang Qi,Sheng-Jie Yuan,Qing-Wen Tian,Si-Xin Wu
Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have been receiving considerable attention in recent years, owing to their low cost and toxicity as well as a high abundance of their constituent elements. Solution-based (mainly precursor solution) methods have been widely used in the fabrication of CZTSSe-based thin film solar cells. Though most record solar cells since 2009 have been achieved using solution-based methods, carbonaceous residues are always formed during post deposition treatment (PDT). These carbonaceous residues are detrimental to grain growth of CZTSSe to form large grains. The presence of unwanted small grain layers will increase the series resistance and reduce the fill factor of the solar cell, thus consequently decreasing the efficiency of CZTSSe solar cells. Herein, we propose “green” supercritical carbon dioxide (SCCO2) treatment to overcome the challenge of carbonaceous residues. FT-IR, SEM, XRD and Raman characterization studies were used to confirm the reduction of carbonaceous residues in CZTSSe films. The solar cell fabricated from a selenized CZTSSe precursor film with SCCO2 treatment under optimal conditions showed the best conversion efficiency of 11.23% (VOC = 0.456 V, JSC = 36.6 mA cm−2, FF = 67.1%). To the best of our knowledge, this is the first report on boosting the efficiency of solution-based CZTSSe solar cells by using SCCO2 treatment. In addition, this unique SCCO2 treatment may also bring forth new ideas for other solution-based optoelectronic devices.
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