JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Meinan Wan,Baoshun Liu,Shuo Wang,Lingting Hu,Youjia He,Haizheng Tao,Xiujian Zhao
Monoclinic (M1) VO 2 film has potential applications in thermochromic modulators owing to the particular optical performance caused by phase transition. However, its controllable preparation is very difficult due to the multivalence of V element. Here, we studied a sol-gel process followed by annealing in a closed vaccum furnace containing NH 3 atmosphere, and discussed the formation mechanism of M1-phase VO 2 films. Thermochromic M1-phase VO 2 thin films can be fabricated under the base pressure of 600–2000 Pa with the annealing temperature at 470–590 °C for more than 0.5 h, and the optimal condition is at 1000–2000 Pa and 500–530 °C for 0.5 h, by synthetically considering their luminous transmittance ( T lum ), solar modulation efficiency ( ΔT sol ), and modulation efficiency at 2000 nm ( ΔT 2000nm ). The M1-phase VO 2 thin film generally exhibits the optical properties with T lum ≈ 39–41%, ΔT sol ≈ 7.7% and ΔT 2000nm ≈ 50%. A higher base pressure introduces more oxygen to remove polymers in precursors, enhancing the transparency of films. Improving the temperature or the duration promotes the growth of VO 2 crystallite with limits. However, inappropriate base pressure, temperature or duration will reduce or oxidize the VO 2 films, resulting in the inferior thermochromic properties. According to thermal and XPS analysis , NH 3 can act as a reductant to prevent oxidation of VO 2 films during the annealing process. This convenient heat treatment method to synthesize M1-VO 2 films may provide a useful and practical technique for the production of VO 2 -based smart window and optical devices.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
ENERGY AND BUILDINGS
·
2024
·
IF 6.6
Ting-Hui Fan,Hao-Qiang Pang,Sheng-Nan Zhang,Guang Lei Yu,Xi Wu
Compared to commercial glass, transparent wood-based windows is provided with better thermal insulation performance, and more comparable solar transmittance. However, transparent wood cannot dynamically regulate solar light switching between summer and winter, and its insulation is worth improving but without a clear micron thermal mechanism model. Herein, a thermochromic and insulation transparent window composed of oriented cellulose attached by VO 2 nanoparticles was prepared, and its thermal conductivity model of micron cellulose, VO 2 nanoparticles, and PMMA polymer was established. The results show that the extinction coefficient of Cell-wall@VO 2 @PMMA is improved to 21.68 % when the VO 2 occurs phase change at near-infrared spectra. The optimal angle of cellulose for comprehensive insulation performance of blocking near-infrared and heat conduction equals 60°. Besides, the transparent wood sample demonstrates a low thermal conductivity of Cell-wall@VO 2 @PMMA, reaching to 0.175 W·m −1 ·K −1 , as well as reducing the temperature difference by 36.8 %. This paper provides a novelty heat transfer perspective for designing thermochromic transparent cellulose with excellent insulation performance in the future.
研究领域:
材料科学
·
能源与环境科学
✓ 已验证
DOI
高影响因子
MATERIALS LETTERS
·
2013
·
IF 2.224
Rong Li,Shidong Ji,Yamei Li,Yanfeng Gao,Hongjie Luo,Ping Jin
Rectangular and plate-like VO 2 (M)@SiO 2 nanoparticles were fabricated by a combination method of hydrothermal synthesis and post annealing process. Rectangular VO 2 (B) nanoplates of 20–30 nm in thickness were hydrothermally synthesized, and VO 2 (B)@SiO 2 core–shell structure was formed using a modified Stober method. Protected by inert SiO 2 shell, after post annealing the VO 2 (B)@SiO 2 was transformed to VO 2 (M)@SiO 2 without deteriorating its original plate-like morphology. Much interestingly, numerous nanopores were formed inside VO 2 (M)@SiO 2 nanoparticles due to the difference in density between VO 2 (B) and VO 2 (M), which contributes to higher optical transmittance and thermal insulation . Thermochromic foils were fabricated using the core–shell nanoparticles, showing promising potential for smart window.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Wenxiong Chen,Honglong Xing,Shengtao Gao,Ping Yang,Xiaoli Ji
The development of heterojunction composite materials with excellent electromagnetic wave absorption performance is emerging as an effective means to address the hazardous electromagnetic waves . Here, two types of Cu 9 S 5 @VO 2 microspheres with different morphologies were designed. The Cu 9 S 5 @VO 2 microspheres were characterized by scanning electron microscopy, transmission electron microscopy , X-ray diffraction, Raman spectroscopy , X-ray photoelectron spectroscopy, and vector network analyzer. Results show that the minimum reflection loss ( RL min ) of unique lamellar-flower Cu 9 S 5 @VO 2 sphere reaches −56.98 dB, and the wide effective absorption bandwidth (EAB) is 6.88 GHz at only 2.5 mm thickness due to the synergistic effect of multiple loss mechanisms. Radar simulated radar cross section (RCS) results show a reduction of 16.56 dBm 2 . The design engineering of the phase interface on the material surface can functionalize the material surface properties, introduce lattice defects and polarization behavior, and improve the microwave absorption performance of the material. This work enriches the use of copper sulfide-based functional composites in microwave absorption with high-performance microwave absorbers by designing microscopically controllable, simple processes and heterojunction design.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF NON-CRYSTALLINE SOLIDS
·
2013
·
IF 1.597
Yuankai Liu,Haizheng Tao,Xinhong Chu,Meinan Wan,Jianhua Bao,Xiujian Zhao
Based on the thermochromic properties of VO 2 , wide applications such as smart windows have been investigated in the world. Using the sol–gel method, series of thermochromic films, including the pure and W-doped VO 2 films, were fabricated on quartz substrate. WCl 6 was used as the source of tungsten . Measurements of temperature dependent transmitting spectra indicated that obvious enhancement of transmitting variance between 30 and 90 °C can be realized through the addition of tungsten. In addition, based on the comparison of thermal hysteresis loops of the W-doped and undoped thermochromic films, the sharpening of temperature width and steepening of temperature–transmittance curves can be clearly seen from the W-doped thermochromic films, which indicated the improved phase change quality compared with the undoped ones. Therefore, the improvement of phase change quality has been realized successfully through the addition of tungsten compound into the thermochromic VO 2 films.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2020
·Vol. 38
·期 12
·1703-1708
·
IF 3.826
Yuxin Wang,Ling Zhang,Jiaying Bi,Hao Yang,Zhikun Zhao,Daobin Mu,Borong Wu
Summary of main observation and conclusion We successfully prepared the Li-VO 2 (M) nanosheets via a facile lithiation method. After compositing with conductive carbon fibers, the sulfur host (Li-VO 2 (M)@CFs) combines the efficient adsorption ability of the VO 2 (M) with superior electronic conductivity of the carbon fibers. Besides, carbon fiber cloth used as the current collector can provide the 3D electronic channels. Therefore, the coin cells exhibited the superior reversible capacity of 1250 mA h g –1 at 0.2 C and a low capacity decay value of 0.068% per cycle within 416 cycles at 1 C, indicative of the favorable cycling stability. Moreover, even at a high rate of 5 C, it also kept at a high discharge capacity of 401 mA h g –1 . In conclusion, this work discloses an attractive route to reduce the dissolution loss of lithium polysulfides (LiPSs) and enhance the overall performance of Li-S batteries.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2015
·
IF 2.999
Hua Zhang,Xiudi Xiao,Xuanming Lu,Guanqi Chai,Yaoming Sun,Yongjun Zhan,Gang Xu
In this paper, high crystallinity and pure phase VO 2 (M) powder is synthesized by a novel and facile method. Aiding by additional manual grinding and etching process, 22 nm high-quality VO 2 (M) nanoparticles can be obtained. The structure and properties of the VO 2 (M) particles were characterized by X-ray diffraction analysis, transmission electron microscopy, differential scanning calorimetry and UV–vis–NIR spectrophotometer. After mixing VO 2 (M) nanoparticles with transparent polymer, thin films prepared by grinded VO 2 nanoparticles show excellent thermochromic properties. The solar modulation ability is up to 12.4% with luminous transmittance of 62.7%. Moreover, The haze of films prepared by grinded VO 2 (M) nanoparticles is down to 1.9%, which is far less than that of films prepared by original VO 2 (Haze = 8.5%) and etched VO 2 particles (Haze = 4.6%). Dramatical improvement of thermochromic property and definition indicate that it is a promising method to prepare large-scale VO 2 nanoparticles and cost-effective smart window.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 18
·15436-15443
·
IF 3.201
Wei Zheng,Rui Wang,Yuemei Li,Yanling Xu,Baoyu Su
Photon upconversion holds tremendous promise in many fields, including photovoltaics, biological imaging, and multi-dimensional display. However, insufficient upconversion emission intensity still limits its utilization for many potential applications. Herein, a type of VO2 (B) nanoflowers with unique size and high crystalline quality, exhibiting a bright upconversion emission, is reported. More importantly, a new method, i.e., higher power-sensitization, is established to improve upconversion emission signals. After higher power-sensitization, a drastic increase in upconversion emission intensity to 553-fold and 158-fold was observed for green and total emissions, respectively, at a pump power of 90 mW. At the same time, the upconversion of light at low excitation powers (2, 90 mW) was observable by the naked eye. We identified that the welded structure, favouring the energy transfer from sensitizers to activators, was key for achieving this enhancement. This study not only suggests a new pathway for building high-efficiency upconversion systems, but also provides insights for improving the practical applications of upconversion materials.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Yunxiang Chen,Xianzhe Zeng,Jingting Zhu,Rong Li,Heliang Yao,Xun Cao,Shidong Ji,Ping Jin
For VO2-based thermochromic smart windows, high luminous transmittance (Tlum) and solar regulation efficiency (ΔTsol) are usually pursued as the most critical issues, which have been discussed in numerous researches. However, environmental durability, which has rarely been considered, is also so vital for practical application because it determines lifetime and cycle times of smart windows. In this paper, we report novel VO2@ZnO core–shell nanoparticles with ultrahigh durability as well as improved thermochromic performance. The VO2@ZnO nanoparticles-based thermochromic film exhibits a robust durability that the ΔTsol keeps 77% (from 19.1% to 14.7%) after 103 hours in a hyperthermal and humid environment, while a relevant property of uncoated VO2 nanoparticles-based film badly deteriorates after 30 h. Meanwhile, compared with the uncoated VO2-based film, the VO2@ZnO-based film demonstrates an 11.0% increase (from 17.2% to 19.1%) in ΔTsol and a 31.1% increase (from 38.9% to 51.0%) in Tlum. Such integrated thermochromic performance expresses good potential for practical application of VO2-based smart windows.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2022
·Vol. 32
·期 40
·2205160
·
IF 19.924
Zheng Cheng,Ruofeng Wang,Yishu Cao,Zhihao Cai,Zhiwei Zhang,Yi Huang
Intelligent microwave absorption (MA) materials possess the ability to dynamically change their microwave absorption performance, according to real-time requirements, and it is of great significance in future civil and military fields. For the first time, the reduced graphene oxide/VO 2 composite aerogels are developed with off/on switchable MA performance, and the switchable mechanism is originated from the unique phase change behavior of VO 2 . As temperature increases (>68 °C), the VO 2 displays the phase change from monoclinic to rutile phase, which accompanies with significant changes in aerogel's electrical conductivity as well as its permittivity, and consequently leads to off/on switchable MA performance. Particularly, two different off/on switch modes, “on to off” and “off to on”, can be separately realized by different composite aerogels as temperature increases, and this off/on switchable MA performance is also confirmed with good cycling stability. More importantly, during the off/on switch process, the maximum changes for the effective absorption bands (ΔEAB) and RL values (ΔRL) can be as high as 7.27 GHz and 49 dB, which exceeds most current reports. Besides, the RCS simulations on aircrafts have been performed and verified this intelligent MA performance, thus providing useful guidance for next-generation smart electromagnetic devices in various fields.
研究领域:
材料科学
·
电磁学
·
智能材料
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2022
·Vol. 16
·期 1
·208
·
IF 3.748
Meinan Wan,Mo Xiong,Shouqin Tian,Xingzhu Chen,Bin Li,Xuesong Lu,Xiujian Zhao
VO2, as a promising material for smart windows, has attracted much attention, and researchers have been continuously striving to optimize the performance of VO2-based materials. Herein, nitrogen-incorporated VO2(M1) thin films, using a polyvinylpyrrolidone (PVP)-assisted sol–gel method followed by heat treatment in NH3atmosphere, were synthesized, which exhibited a good solar modulation efficiency (ΔTsol) of 4.99% and modulation efficiency of 37.6% at 2000 nm (ΔT2000 nm), while their visible integrated transmittance (Tlum) ranged from 52.19% to 56.79% after the phase transition. The crystallization, microstructure, and thickness of the film could be regulated by varying PVP concentrations. XPS results showed that, in addition to the NH3atmosphere-N doped into VO2lattice, the pyrrolidone-N introduced N-containing groups with N–N, N–O, or N–H bonds into the vicinity of the surface or void of the film in the form of molecular adsorption or atom (N, O, and H) filling. According to the Tauc plot, the estimated bandgap of N-incorporated VO2thin films related to metal-to-insulator transition (Eg1) was 0.16–0.26 eV, while that associated with the visible transparency (Eg2) was 1.31–1.45 eV. The calculatedEg1andEg2from the first-principles theory were 0.1–0.5 eV and 1.4–1.6 eV, respectively. The Tauc plot estimation and theoretical calculations suggested that the combined effect of N-doping and N-adsorption with the extra atom (H, N, and O) decreased the critical temperature (τc) due to the reduction inEg1.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Xin-ya Bu,Yan-li Zhu,Yu Xia,Bin-chao Shi,Shu Zhang,Xiao-yu Wei,Jing Luo,Yi Zhang,Ting Quan
Thermal batteries are a type of thermally activated reserve batteries, where the cathode material significantly influences the operating voltage and specific capacity of the battery. In this work, VS 4 -VO 2 has been synthesized through the hydrothermal method and used as the cathode material for thermal batteries. Firstly, the material with the VS 4 crystallinity is obtained at 170 °C and the mass percentages of VS 4 /VO 2 are 63.1 % and 36.9 %, respectively. The formation mechanism of VS 4 -VO 2 has been proposed based on in-situ ultraviolet (UV) spectrum, which shows that the hydrolysis product S 2- under alkaline conditions promotes the formation of VS 4 . To further improve the conductivity of the material, the reduced graphene oxide (rGO) has been introduced into VS 4 -VO 2 nanomaterials. When applied in thermal batteries, the rGO-VS 4 -VO 2 composite exhibits a voltage plateau of approximately 2.4 V and a discharging specific capacity of 327 mAh/g with the cut-off voltage of 1.5 V at 50 mA and 350°C, which are higher than those of VS 4 -VO 2 . Furthermore, the discharge mechanisms of rGO-VS 4 -VO 2 in thermal batteries have been analyzed, which indicates that VS 4 -VO 2 involves two processes of phase transformation, including the intercalation process and conversion process. The results confirm rGO-VS 4 -VO 2 as a promising cathode material for thermal batteries.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）