Small
·
2021
·Vol. 18
·期 8
·2105599
·
IF 13.281
Wuhong Xue,Qitao Jiang,Fakun Wang,Ri He,Ruixue Pang,Huali Yang,Peng Wang,Ruilong Yang,Zhicheng Zhong,Tianyou Zhai,Xiaohong Xu
2D ferroelectrics with robust polar order in the atomic-scale thickness at room temperature are needed to miniaturize ferroelectric devices and tackle challenges imposed by traditional ferroelectrics. These materials usually have polar point group structure regarding as a prerequisite of ferroelectricity. Yet, to introduce polar structure into otherwise nonpolar 2D materials for producing ferroelectricity remains a challenge. Here, by combining first-principles calculations and experimental studies, it is reported that the native Ga vacancy-defects located in the asymmetrical sites in cubic defective semiconductor α‑Ga 2 Se 3 can induce polar structure. Meanwhile, the induced polarization can be switched in a moderate energy barrier. The switched polarization is observed in 2D α‑Ga 2 Se 3 nanoflakes of ≈4 nm with a high switching temperature up to 450 K. Such polarization switching could arise from the displacement of Ga vacancy between neighboring asymmetrical sites by applying an electric field. This work removes the point group limit for ferroelectricity, expanding the range of 2D ferroelectrics into the native defective semiconductors.
研究领域:
材料科学
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凝聚态物理
·
纳米电子学
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功能材料
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半导体物理
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yuqing Sun,Adeel Abbas,Hongxiang Wang,Chang Tan,Zhihao Li,Yujie Zong,Hui Sun,Chunlei Wang,Hongchao Wang
Quaternary Cu 2 MnSnSe 4 alloys with low intrinsic thermal conductivity are identified as promising middle-temperature thermoelectric materials. However, zT is depressed by the poor electrical performance. To overcome this issue, here, a series of Cu 2.1 Mn 0.9 SnSe 4 samples are prepared by ball-milling method which appears as a time-saving technique and lattice strain variation is observed by changing the annealing time ( x = 0, 1, 2, 3, 4 days). The vacancy defects concentration of Cu, with lowest vacancy defects formation energy, is changed with the competition between compression and tension-strain state, consistent with the first principles calculations, which optimizes the carrier transport. As a result, about 4 times increment of the carrier mobility is found. Moreover, the lattice strain of several nanometers is observed with TEM analysis, which scatters phonon strongly. A lowest κ L value of 0.57 W m −1 K −1 at 673 K is obtained for x = 3 sample, which is close to the amorphous limit. The interactive effect of enhanced mobility and strong scattering of phonons, contributing to a record zT ∼ 0.48 at 673 K for x = 3 sample. Lattice strain engineering is an effective tactic to simultaneously optimize the electrical and thermal transport.
研究领域:
材料科学
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凝聚态物理
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功能材料
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能源材料
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半导体物理
✓ 已验证
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2022
·
IF 9.794
Die Su,Jianping Yang,Qingshui Hong,Min Yang,Jiaxing Wen,Qianfu Wang,Hai Hu,Li Liu,Xiukang Yang
Pseudo-capacitive materials show long cycling life as anode of K-ion battery (KIBs), yet low specific capacity and poor rate performance. Herein, the porous TiNbO 4 /C nanofibers (denoted as TNO/C) are synthesized via electro-spinning. Abundant oxygen vacancies and large specific surface area make the sample exudes high specific capacity and good rate performance. After optimizing the calcination temperature, it is found that the porous TiNbO 4 /C nanofibers at 700 °C (denoted as TNO/C-700) can deliver the specific discharge capacity of 250.4 mAh g −1 in K-ion half cell and demonstrate good cycle stability for 100 cycles in K-ion full cell in 100 mA g − 1 . Even in 5 A g − 1 , the discharge capacity of TNO/C-700 electrodes is still 116.7 mAh g − 1 at rate performance. Ex-situ XRD results show that this TNO/C-700 electrode is associated with pseudo-capacitive effect and insertion/de-insertion process. The TNO/C-700 electrode exhibits a high pseudo-capacitive contribution, which can reach to 85.0% at 3 mV s −1 . This novel high pseudo-capacitive contribution anode material provides more possibilities for the selection in KIBs.
研究领域:
材料科学
·
电化学
·
能源存储
·
纳米材料
·
无机非金属材料
✓ 已验证
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2022
·Vol. 24
·期 44
·27105-27113
·
IF 3.945
Panpan Peng,Chao Wang,Lanwei Li,Shuyao Li,Jing Chen,Pengya Fan,Rui Du,Haotian Si,Zhenxiang Cheng,Jianli Wang
Endotaxial nanostructures can reduce lattice thermal conductivity through enhancing phonon scattering without affecting electrical transport, leading to a high thermoelectric performance. On the other hand, band engineering can enhance electrical transport by improving the Seebeck coefficient through valence band convergence and the resonance level. In this paper, the synergistic effect of band engineering and endotaxial nanostructures was implemented in SnTe thermoelectric materials by alloying with AgCuTe and doping with Indium. The positron annihilation lifetime spectra show that the vacancy concentration in SnTe was reduced after alloying with AgCuTe, which led to a decreasing hole concentration and improved carrier mobility. Additionally, the diffusion of Ag in the matrix during the preparation can facilitate valence band convergence. Therefore, the power factor of SnTe is greatly increased to 18 μW cm−1 K−2 at 800 K, which can be further increased to 21.4 μW cm−1 K−2 at 800 K after In doping due to resonance level formation. Meanwhile, Cu2Te endotaxial nanostructures also can be observed in the TEM image after SnTe alloying with AgCuTe. So, the lattice thermal conductivity significantly reduced to 0.93 W m−1 K −1 in In-doped and AgCuTe-alloyed SnTe. Finally, we obtain an enhanced ZT value of 1.14 in Sn1.02In0.01Te–1%AgCuTe at 800 K.
研究领域:
材料科学
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凝聚态物理
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功能材料
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热电转换
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纳米结构调控
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半导体物理
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能源材料
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Jing Jiang,Jiayi Zhang,Baihao Wu,Sheng Tu
The regulation of the metal-support interaction in heterogeneous catalysts can promote the activation of reactants, which is beneficial for the hydrolytic dehydrogenation reaction. Herein, the hydrolytic dehydrogenation of dimethylamine borane (DMAB) is systematically studied on the oxygen vacancy (O v ) enriched Pt-Co 3 O 4 heterogeneous catalyst with the metal-support interaction. It is found that the metallic Pt site facilitates the adsorption of DMAB molecules and the O v on Co 3 O 4 support as an electron-rich center cooperates with the adjacent Pt site to dissociate water molecules. The in situ Raman and attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy reveal the effective activation and cleavage of the O-H in water and the B-H in DMAB over the Pt-Co 3 O 4 catalyst. The optimal Pt-Co 3 O 4 catalyst exhibits the extraordinary activity for the catalytic hydrolysis of DMAB at 303 K, delivering a high specific hydrogen generation rate (64063 mL min −1 g pt −1 ) and a competitive turnover frequency (TOF, 23880 mol H2 mol Pt −1 h −1 ). This performance outperforms most of the reported heterogeneous catalysts for DMAB dehydrogenation . More importantly, the Pt-Co 3 O 4 catalyst achieves the desirable on-demand hydrogen production by using special chemical switches. This finding provides the fundamental understanding of metal-oxide systems with the collaborative interfacial catalysis for boosting DMAB dehydrogenation .
研究领域:
催化化学
·
纳米材料科学
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能源化学
·
表面科学
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多相催化
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氢能存储与释放
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Bing Yang,Bo Wang,Peng Li,Jing Chen,Bo Li,Lushan Ma,Futian Zhang,Haitao Guo,Yunfeng Tian,Xuzhuo Sun,Bo Chi
In this study, we developed an innovative strategy to fabricate perovskite oxide powder with 12.356 m 2 /g of specific surface area. Polyacrylamide hydrogel was used as a template to prepare Sm 0.5 Sr 0.5 CoO 3-δ (SSC) powders with lamellar structure. The three-dimensional interconnected structured SSC electrodes with lamellar connections were fabricate using screen printing method. As a result, the oxygen vacancy concentration of the SSC powder obtained by the polyacrylamide template method was 0.625 and 0.642 at 650 °C and 700 °C respectively. At 650°C, the polarization resistance value was 0.11 Ω cm 2 for the novel SSC-PAM-V cathode. Compared with the SSC-SG cathode, the polarization resistance and activation energy of SSC-PAM-V were reduced by 50 % and 6.9 %, respectively. Furthermore, in a single cell with SSC-PAM-V electrodes, we achieved a maximum power density of 935 and 1243 mW cm −2 at 650 °C and 700 °C under wet H 2 conditions, demonstrating good electrochemical output performance. The layered porous electrode was not only suitable for the diffusion of oxygen, but also for increasing the reactive active sites. The proposed powder prepared with polyacrylamide hydrogel as template, was not only suitable for the optimization of perovskite oxide, but also for the application in other types of catalysis, providing the potential for improving the electro-catalytic activity of perovskite electrodes.
研究领域:
材料科学
·
电化学
·
能源材料
·
催化化学
·
固体离子学
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2021
·
IF 9.676
Pengfei Zhou,Jing Zhang,Zhennan Che,Zuhao Quan,Ju Duan,Xiaozhong Wu,Junying Weng,Jinping Zhao,Jin Zhou
P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 is considered as a promising cathode material for sodium-ion battery (SIBs) because of its high capacity and discharge potential. However, its practical use is limited by Na + /vacancy ordering and P2-O2 phase transition. Herein, a Ti 4+ /F − co-doping strategy is developed to address these issues. The optimal P2-Na 0.67 Ni 0.33 Mn 0.37 Ti 0.3 O 1.9 F 0.1 exhibits much enhanced sodium storage performance in the high voltage range of 2.0–4.4 V, including a cycling stability of 77.2% over 300 cycles at a rate of 2 C and a high-rate capability of 87.7 mAh g −1 at 6 C. Moreover, the P2-Na 0.67 Ni 0.33 Mn 0.37 Ti 0.3 O 1.9 F 0.1 delivers reversible capacities of 82.7 and 128.1 mAh g −1 at −10 and 50 °C at a rate of 2 C, respectively. The capacity retentions over 200 cycles at −10 °C is 94.2%, implying more opportunity for practical application. In-situ X-ray diffraction analysis reveals that both P2-O2 phase transitions and Na + /vacancy ordering is suppressed by Ti 4+ /F − co-doping, which resulting in fast Na + diffusion and stable phase structure. The hard carbon//P2-Na 0.67 Ni 0.33 Mn 0.37 Ti 0.3 O 1.9 F 0.1 full cell exhibits a high energy density of 310.2 Wh kg −1 and remarkable cyclability with 82.1% retention after 300 cycles at 1 C in the voltage range of 1.5–4.2 V. These results demonstrate that the co-doping Ti 4+ /F − is a promising strategy to improve the electrochemical properties of P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 , providing a facile tactic to develop high performance cathode materials for SIBs.
研究领域:
材料科学
·
电化学
·
能源存储
·
无机化学
·
固态化学
·
电池技术
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2022
·Vol. 10
·期 6
·108837
·
IF 7.968
Yumei Jian,Ye Meng,Jie Li,Hongguo Wu,Shunmugavel Saravanamurugan,Hu Li
Photocatalytic reductive conversion of bio-derivatives to biofuels and fine chemicals is an eco-friendly and energy-saving way for biomass valorization. Herein, we developed a new and high-performance protocol for control of activity/selectivity in photocatalytic reductive upgrading of biomass to biofuels at room temperature via engineering oxygen vacancy (Ov) and manipulating the exposed crystal surfaces of the TiO 2 -based catalysts, such as efficient cascade photocatalytic hydrogenation-cyclization of ethyl levulinate to γ-valerolactone in water (up to 96% yield, TOF: 112.1 h −1 ), and the selective conversion of 5-methylfurfural to 5-methylfurfuryl alcohol (90% yield) or long carbon-chain coupling products (86% yield) in methanol, respectively. The {101} crystal plane is prone to produce more Ov in situ than the {001} and {110} crystal planes. The formation of Ov was not only beneficial to the adsorption and activation of the bio-based carbonyls, but also could enhance the migration efficiency of the photo-generated carriers and effectively adjust the semiconductor band structure of the TiO 2 -based photocatalyst to promote the visible-light absorption, thus enhancing the overall reductive conversion process, as elucidated by DFT calculations. Also, the charge distribution and adsorption intensity of different exposed crystal surfaces of the photocatalyst were able to control the selectivity of the bioproducts . In addition, the optimal Ov-TiO 2− x {101} catalyst had excellent reusability and could be reused at least five times with no obvious decrease in photocatalytic performance. The strategy of selectivity control via engineering the catalyst exposed crystal surfaces and loaded Ov provides an opportunity for multi-catalytic biomass conversion to biofuels.
研究领域:
催化化学
·
材料科学
·
能源化学
·
环境科学
·
绿色化学
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表面科学
·
光催化
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Yuxing Sun,Lei Zhao,Juan Yang,Xiang Wang,Huanjun Peng,Jingdong Peng
Light absorption range, recycling stability and charge transfer efficiency are key to the performance of photocatalytic material. Based on these targets, a Al doped TiO 2 catalyst was synthesized by the evaporation-induced process, after processed by NaBH 4 reduction, the black TiO 2 doped with Al was finally prepared. Uv-vis DRS, EPR and XPS analyses confirm the expanded light absorption window (300 nm - 1000 nm) and the introduction of abundant oxygen vacancy after the reduction process. The final product BTiO 2 /Al-0.5 has a degradation rate of about 84 % over the tetracycline hydrochloride within 60 minutes, the reaction rate constant (k) is 10.6 times higher than the unreduced sample. The dramatic change of photocatalytic ability can be assigned to the broadened visible light absorption , increased charge separation efficiency, narrowed band gap and defect-enriched oxygen vacancy . This work offers insights into the fabrication of TiO 2 catalyst and the introduction of oxygen defect.
研究领域:
材料科学
·
光催化
·
环境功能材料
·
纳米材料
·
表面化学
·
半导体催化
✓ 已验证
DOI
高影响因子
PHYSICA B-CONDENSED MATTER
·
2022
·
IF 2.988
Wei Zhang,Zhiwei Gu,Bingbing Zong,Yueju Fu,Kai Zhang,Yubao Li
Defects is of special importance in tuning the structure and physical properties of layered materials. Here the influence of transition metal Co vacancies on the structure and magnetism in collapsed tetragonal CaCo 2- x As 2 (0 ≤ x ≤ 0.3) solid solutions are systematically investigated. The electrical properties show metallicity in all compounds. The crystal structure refinement exhibits that the lattice constant of the c axis and c / a ratio decreases as Co vacancies increase, revealing the formation of a more collapsed tetragonal structure in CaCo 2- x As 2 . Moreover, these introduced Co vacancies suppress the antiferromagnetic Néel temperature from 80 K down to 18 K until it disappears above 10 K in CaCo 1 · 7 As 2 . X-ray photoelectron spectroscopy reveals increased Co 3+ /Co 2+ value in CaCo 2- x As 2 with higher Co vacancies, which may result in the charge balance and the gradually suppressed T N . This study offers insights into tuning and understanding the magneto-structural characteristics in ThCr 2 Si 2 -type layered materials through transition metal vacancies.
研究领域:
凝聚态物理
·
材料科学
·
固体化学
·
磁学
·
晶体工程
·
缺陷工程
✓ 已验证
DOI
高影响因子
MATERIALS RESEARCH BULLETIN
·
2012
·Vol. 47
·期 11
·3277-3282
·
IF 2.105
Jing Bo Zhang,Xiao Ning Li,Shou Li Bai,Rui Xian Luo,Ai Fan Chen,Yuan Lin
Well-crystallized one-dimensional (1D) SnO 2 nanobelts were in situ prepared using a simple water-assisted chemical vapor deposition (CVD) method. The small Sn particles with Au-modifications were used as source materials instead of big size Sn grains to ensure the high yield of SnO 2 belts. The Au layer was modified on the small Sn particles by treating Sn powders in HAuCl 4 solution combined with the UV irradiation. The as-prepared SnO 2 nanobelts were characterized by SEM, HRTEM, XRD, EDS and XPS. These results indicate that the growth temperature plays an important role in controlling the length-to-width ratio of nanobelts. The length-to-width ratio decreases with the growth temperature from 850 °C to 1000 °C. The nanobelts prepared at 850 °C shows a single-crystalline tetragonal rutile phase with a high length-to-width ratio (approximately tens of microns in length and 40–70 nm in width). However, below 850 °C, nanobelts cannot be formed. The as-prepared nanobelts exhibited excellent sensing properties compared with SnO 2 nanoparticles and high sensing selectivity towards NO 2 . The high sensing selectivity to NO 2 is attributed to the oxygen vacancies presenting in the as-prepared nanobelts.
研究领域:
材料科学
·
纳米技术
·
传感器学
·
无机化学
·
半导体材料
✓ 已验证
DOI
高影响因子
Materials Today Physics
·
2022
·
IF 11.021
Zilin Ruan,Jianchen Lu,Baijin Li,Qizan Chen,Zhenliang Hao,Lei Gao,Jinming Cai
Structural defects in two-dimensional materials offer an effective way to engineer their functionalities. In-situ local measurements to build the structure-function relationship are crucial for future device technology. Here, we present a comprehensive study of intrinsic defects in single-layer WS 2 grown by chemical vapor deposition using a combination of scanning tunneling microscopy/spectroscopy, non-contact atomic force microscopy and density functional theory calculations. We probed the rarely observed positively charged defects and the intersection of adjacent charging rings at sufficiently high bias caused by subsurface defects. We also directly identified and visualized the widely observed negatively charged defects as chalcogen vacancies-related defects. The results reported here will guide future efforts of targeted defect engineering and doping of the single-layer transition metal dichalcogenides .
研究领域:
材料科学
·
凝聚态物理
·
纳米科技
·
表面科学
·
二维材料
·
半导体物理
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）