RSC Advances
·
2016
·Vol. 6
·期 74
·70452-70459
·
IF 3.289
Makkawi Osman,Yanmin Huang,Wei Feng,Guangbo Liu,Yunfeng Qiu,PingAn Hu
Phase engineering of two-dimensional (2D) materials offers unique opportunities for acquiring novel opto-electronic properties and allows for the searching of outstanding candidates for applications in opto-electronic detectors, sensors, catalysis, or phase-change memory devices. Here, we report the phase-transformation from β-InSe to γ-In2Se3, exploiting the thermal annealing route to trigger the process starting at 200 °C that expands the family of phase-change materials. The presence of γ-In2Se3 is solidly confirmed by the characteristic peaks in X-ray diffraction (XRD) and energy dispersive X-ray (EDX), and is quite stable at ambient condition, thus facilitating substantial application in phase-change memory devices. A Raman shift in the A′1 mode from 225 cm−1 to 230 cm−1 further illustrates the phase transformation. Besides the photoluminescence (PL) peak of β-InSe, the ∼2 eV PL peak, ascribed to γ-In2Se3, is observed in the annealed nanosheet. The increased PL band gap of β-InSe as a function of annealing temperature during phase transformation was possibly affected by the suppressed interlayer coupling, as well as the planar quantum confinement of photo-excited carriers by the external surfaces of the sheets. The photodetector performance with respect to photocurrent, mobility, detectivity, responsivity, and external quantum efficiency was subsequently evaluated after thermal annealing, showing deteriorated optical performance. The present work proved that thermal annealing could induce the successful phase transformation, and adjusted the opto-electronic properties in some extent, providing useful information for processing 2D materials based nano-devices.
研究领域:
材料科学
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光学工程
·
纳米技术
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产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2019
·
IF 5.383
Shuang Gao,Dan Wang,Yinglin Wang,Chuang Li,Yichun Liu,Norihiro Suzuki,Chiaki Terashima,Akira Fujishima,Xintong Zhang
Doping with tetravalent titanium cation impurities is an effective means to enhance the performance of hematite (α-Fe 2 O 3 ) photoanodes. These nevertheless face problems of inefficient activation of impurity donors, which thereby impairs the photoelectrochemical water oxidation property of hematite. Herein, we propose a simple method to activate Ti 4+ dopants in spray-pyrolyzed hematite thin films via a rapid thermal annealing (RTA) treatment. The donor carrier density of Ti-doped Fe 2 O 3 thin films (doping level, i.e., Ti/Fe: 0.5–10%) is significantly increased by RTA at 700 °C for 30 s, for instance, ca. 1.35 × 10 19 cm −3 at the doping level of 5% (5%-Ti:Fe 2 O 3 -700). This is 19.3 times as high as those treated by traditional annealing in a muffle furnace at 500 °C for 1800 s (5%-Ti:Fe 2 O 3 -500). A photocurrent density of 5%-Ti:Fe 2 O 3 -700 for water oxidation reaches 0.91 mA cm −2 at 1.23 V vs. RHE. This is ca. 6-fold higher than 5%-Ti:Fe 2 O 3 -500. Electrochemical impedance spectroscopy , XRD, Raman spectroscopy, and scanning probe microscopy measurements suggest that RTA performs more efficiently than traditional annealing for promoting the substitutional incorporation of Ti 4+ cations into the hematite lattice. This simple RTA treatment for donor-activation should be applicable to other semiconductor-dopant combinations—thin films or nanostructures , for the development of high-performance photoanodes for water oxidation.
研究领域:
材料科学
·
电化学
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Weijun Gui,Mingzhe Du,Xianmin Zhang,Miroslav Almáši,Lijia Wan,Lu Gan,Zhenxi Wang,Suhang Wu
The limited luminescence efficiency and poor stability of lanthanide-based metal-organic frameworks (Ln-MOFs) are the key factors restricting their practical applications. It is well known that high-temperature annealing can significantly enhance the photoelectric properties of inorganic materials, but it seems unfeasible for Ln-MOFs due to the existence of organic components. To overcome this dilemma, MOF-76 was synthesized by hydrothermal method and then hydrothermally annealed at 140 °C for 4 h. As a result, the annealing not only significantly improves the crystallinity of MOFs but also promotes their transition from the original tetragonal phase to the monoclinic phase. The annealed MOFs ( a MOF) exhibit about 3-fold emission enhancement and show better stability, especially under alkaline conditions or in water or saturated alkanes, such as cyclohexane, and dichloromethane. The total emission intensity of the as-prepared (AP) MOF is reduced to less than 1/10 compared to the a MOF due to the influence of water molecules. When the material was immersed in a mixture of ammonia and water, the a MOF emission remained stable, while the AP MOF emission rapidly decreased to approximately 12 % with an increasing volume ratio. Additionally, a notably enhanced 5 D 0 → 7 F 1 transition of Eu 3+ ions in MOF-76 has been observed for the first time. It was found that after hydrothermal annealing, the photoluminescence quantum yield of the MOF increases from 10.86 % to 61.48 %, and its synthesis yield can reach 73.8 %. The properties described above remarkably enhance the application values of the a MOFs. Interestingly, MOFs can also be solvothermal annealed, thus the schemes presented in this context open up novel approaches to significantly improve/modify the performance of other MOF materials. Finally, the obtained green and red emitting a MOFs combined with the N-CDs@starch were applied to warm white LED with the colour coordinates (CIE) of (0.3662, 0.3544), colour rendering index (CRI) of 88.5 and correlated colour temperature (CCT) of 4261 K.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2021
·Vol. 14
·期 9
·2426
·
IF 3.623
Xiaoyuan Fan,Peng Du,Xiaoxuan Ma,Ruyue Wang,Jingteng Ma,Yonggang Wang,Dongyu Fan,Yuanzheng Long,Bohan Deng,Kai Huang,Hui Wu
Production of hydrogen from water splitting has been considered as a promising solution for energy conversion and storage. Since a noble metal-based structure is still the most satisfactory but scarce kind of catalyst, it is significant to allow for practical application of such catalysts by engineering the heterogeneous structure and developing green and facile synthetic strategies. Herein, we report a mechanochemical ball milling synthesis of platinum nanoclusters immobilized on a 2D transition metal carbide MXene (Nb2CTx) as an enhanced catalyst for hydrogen evolution. After annealing at 600 °C, ultrafine Pt3Nb nanoclusters are formed on the Pt/Nb2CTxcatalyst. As prepared, the Pt/Nb2CTx-600 catalyst demonstrates superior electrochemical HER activity and stability with an ultralow overpotential of 5 mV and 46 mV to achieve 10 mA cm−2and 100 mA cm−2, respectively, in comparison with other Nb2CTx-based catalysts and commercial Pt/C catalysts. Moreover, the remarkable durability is also confirmed by accelerated durability tests (ADTs) and long-term chronoamperometry (CA) tests. The excellent HER performance was attributed to high Pt dispersion and more active site exposure by the mechanochemical process and thermal treatment. Such results suggest that the mechanochemical strategy provides a novel approach for rational design and cost-effective production of electrocatalysts, also providing other potential applications in a wide range of areas.Keywords:hydrogen evolution;Pt-Nb alloy;mechanochemical synthesis;thermal annealing
研究领域:
材料科学
·
电催化
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2018
·
IF 3.927
Chunli Liu,Yuxuan Sun,Zhenbin Chen,Suobo Zhang
An integrally skinned dense ultrafiltration (UF) membrane was prepared using partially di-quaternized poly(sulfone- co -ethernitrile) random copolymer (PSF- co -DQAPEN) via classical nonsolvent induced phase inversion process (NIPS). Then the original UF membrane was molecularly restructured through a combined process of chemical quaternization-crosslinking reaction and thermal annealing for the preparation of a crosslinked nanofiltration (NF) membrane, in which p -xylylene dichloride (PXDC) and isopropanol were employed as crosslinking agent and nonsolvent treating medium, respectively. The influence of reaction time and crosslinker concentration on membrane performance were investigated. X-ray photoelectron spectroscopy (XPS) of membrane surface and solubility test of membrane were employed to study the chemical composition and crosslinking properties of membranes, and those results revealed that the original membrane had been successfully crosslinked after this post treatment process. The separation performance of membrane was ultimately changed from UF-level to NF-level after the quaternization-crosslinking reaction and thermal annealing treatment process. The optimum crosslinked NF membrane possessed MgCl 2 rejection of 98.2% and water permeate flux of 4.12 L m −2 h −1 bar −1 . Moreover, owning to the excellent chemical stability of membrane material, the crosslinked membrane had outstanding resistance to chlorine, acid and base, thus it can be used for water softening and removing of positive dyes. Given the convenience and feasibility of this modification method, integrally skinned NF membrane could be easily fabricated via the post chemical crosslinking and thermal annealing process of UF membrane using proper treating approaches.
研究领域:
材料科学
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环境工程
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产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 85
·69854-69860
·
IF 3.84
Suyun Tian,Jing Sun,Siwei Yang,Peng He,Shengju Ding,Guqiao Ding,Xiaoming Xie
Rapid thermal exfoliation/reduction of graphite oxide is a fast and easy method among the oxidation–reduction approaches for graphene synthesis. In this research, we firstly demonstrated that graphene can be obtained with a surface area of 550 to 700 m2 g−1 and a yield of approximately 50% through one-step rapid thermal treatment in air from 450 to 550 °C, without vacuum or protective gas through a self-protection process. Then, we further demonstrated the effective two-step thermal annealing to significantly improve the C/O ratio from ca. 7.3 to 25.9 in air at the relatively low temperature of 600 °C. The smart self-protecting and enhanced-oxygen-removal mechanisms were discussed.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Nanoscale Advances
·
2020
·Vol. 2
·期 4
·1523-1530
·
IF 0
Ting Qu,Song Guan,Xiaoxiong Zheng,Aihua Chen
The highly ordered perpendicularly aligned cylindrical and lamellar microdomains within block copolymer (BCP) films have important applications in diverse fields. However, the fast normal orientation of self-assembled nanostructures on arbitrary substrates without tedious pre- and postprocessing has been a challenging issue in manufacturing miniaturized devices. Here, we outline the potential for extending the hierarchical self-assembly within azobenzene-containing PS-b-PMA(Az) films to inherently assist in the formation of normally aligned domains using a rapid thermal annealing process (140 °C for 5 min). Liquid crystalline (LC) mesogens in PS-b-PMA(Az) films self-assemble to form a parallelly aligned sematic phase after thermal annealing, as confirmed by grazing-incidence small-angle X-ray scattering (GISAXS), wide-angle X-ray diffraction (WAXD) and ultraviolet-visible (UV-vis) spectra. This sub-phase contributes to broadening of the PS-cylinder-phase window (0.083 ≤ fPS < 0.49) and ∼12 nm PS cylinder structures. Perpendicular cylinders or lamellae are observed on various substrates, such as silicon wafers, flexible polyethylene terephthalate (PET) sheets and conductive aluminum foils. Additionally, the good reactive ion etching (RIE) rate difference between the two blocks makes these BCPs more attractive for advancing the field of BCP lithographic applications for fabricating flexible microelectronic devices.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
Materials Research Express
·
2018
·Vol. 5
·期 6
·066404
·
IF 1.151
Fujin Jia,Yanqun Guo,Lijia Che,Zhiyong Liu,Zhigang Zeng,Chuanbing Cai
Although the two-step sequential deposition method provides an efficient route to fabricate high performance perovskite solar cells (PSSCs) with increasing reproducibility, the inefficient and incomplete conversion of PbI2 to perovskite is still quite a challenge. Following pioneering works, we found that the conversion process from PbI2 to perovskite mainly involves diffusion, infiltration, contact and reaction. In order to facilitate the conversion from PbI2 to perovskite, we demonstrate an effective method to regulate supersaturation level (the driving force to crystallization) of PbI2 by solventing-out crystallization combining with subsequent time-delay thermal annealing of PbI2 wet film. Enough voids and spaces in resulting porous PbI2 layer will be in favor of efficient diffusion, infiltration of CH3NH3I solution, and further enhance the contact and reaction between PbI2 and CH3NH3I in the whole film, leading to rapid, efficient and complete perovskite conversion with a conversion level of about 99.9%. Enhancement of light harvesting ranging from visible to near-IR region was achieved for the resultant high-quality perovskite. Upon this combined method, the fabricated mesostructured solar cells show tremendous power conversion efficiency (PCE) improvement from 3.2% to about 12.3% with less hysteresis owing to the simultaneous enhancement of short-circuit photocurrent density (Jsc), open-circuit voltage (Voc) and fill factor (FF).
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
SOLID-STATE ELECTRONICS
·
2016
·
IF 1.345
Xu Li,Yue Lu,Li Guan,Jiantao Li,Yichao Wang,Guoyi Dong,Aiwei Tang,Feng Teng
Hybrid organic/inorganic electrically bistable devices (EBDs) based on Cu 2 S/PVK nanocomposites have been fabricated by using a simple spin-coating method. An obvious electrical bistability is observed in the current-voltage ( I - V ) characteristics of the devices, and the presence of the buffer layer and the annealing process have an important effect on the enhancement of the ON/OFF current ratios. Different electrical conduction mechanisms are responsible for the charge switching of the devices in the presence and absence of the buffer layer.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2022
·
IF 4.432
Hanwen Lai,Xiaohui Zhang,Guangcheng Huang,Yadong Liu,Weihua Li,Shengxiang Ji
Directed self-assembly (DSA) of block copolymers (BCPs) is an effective approach for the fabrication of sub-10 nm features for semiconductor devices. Although many high-χ BCPs have been developed for DSA, the majority of them has a significant difference in surface energies (γs) between two blocks. Here we report the synthesis and self-assembly of poly (styrene- b -vinyl acetate) (PS- b -PVAc). PS- b -PVAc has a higher Flory-Huggins interaction parameter (χ) than poly (styrene- b -methyl methacrylate) (PS- b -PMMA) and the smallest achievable period ( L O ) is 18.2 nm. PS and PVAc have nearly equal γs and a perpendicular orientation of domains is obtained on random copolymer brushes under thermal annealing. DSA of PS- b -PVAc (SV-1 and SV-2) is successfully demonstrated in the thin films on chemical patterns, and the feature size down to 9.5 nm is obtained in DSA of SV-4 with 2 × density multiplication. These results demonstrate that PS- b -PVAc could be a candidate BCP for next-generation DSA lithography.
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
Polymer Chemistry
·
2013
·Vol. 4
·期 15
·4245-4255
·
IF 5.231
Yeli Fan,Baoping Lin,Ying Sun,Xiaohui Gong,Hong Yang,Xueqin Zhang
Two novel polymers (PFMA-Ma and PFMA-Mb) were synthesized through an efficient and simple method combining conventional free radical polymerization and a Diels–Alder reaction. Different molar percentage compositions of the functionalized pendants in the polymers and two different steric configurations: endo and exo in the D–A adduct structures are revealed in 1H NMR spectra. In addition, DSC curves demonstrate that the reverse Diels–Alder reactions take place at higher temperatures (between 120 °C and 150 °C). Moreover, both of the fluorescence intensities of the two polymer films (PFMA-Ma (x = 0.700) and PFMA-Mb (x = 0.609)) become weak and even almost disappear with the increase of the annealing temperature, indicating that thermal annealing induces π–π stacking and aggregation of the pendants in the polymers. Concurrently, as the molar ratios of pendant moieties in the polymers are increased, a characteristic peak of face-to-face stacking appears in the fluorescence spectra of PFMA-Ma and a slight red-shift is observed in the fluorescence spectra of PFMA-Mb. These phenomena suggest that high molar percentage of pendants is also beneficial to their π–π stacking and aggregation. This study may provide some insights into the stacking of pendants in polymers and its influencing factors, which will be useful when these polymer materials are applied in optoelectronic devices.
研究领域:
材料科学
·
有机化学
·
光电子学
✓ 已验证
DOI
高影响因子
MATERIALS LETTERS
·
2024
·
IF 2.7
Dapeng Gu,Hongtao Luo,Siyuan Gao,Zhi Li,Suwen Chen,Sen Zhou
A novel method for preparing the superhydrophobic polytetrafluoroethylene (PTFE) surface by doped copper (Cu) to alter microtexture (microscale warts) characteristics is proposed. Microscale warts are generated on the PTFE surface by thermal annealing. The present method achieves superhydrophobicity by adjusting Cu content to alter the morphology and distribution of microscale warts on the PTFE surface. As Cu content increases, the average area and percentage of microscale warts increase, but the density of microscale warts on the PTFE surface first increases and then decreases. An appropriate amount and size of microscale warts are obtained at 2.5 vol% Cu content. PTFE surface doped with 2.5 vol% Cu also has the best superhydrophobicity performance (water contact angle is 162.54°, water sliding angle is 5.90°).
研究领域:
材料科学
·
表面工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）