Journal of Materials Chemistry C
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2018
·Vol. 6
·期 46
·12631-12637
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IF 5.976
Kang Yuan,Xinghua Zhang,Ruohan Qin,Xuefeng Ji,Yahui Cheng,Lanlan Li,Xiaojing Yang,Zunming Lu,Hui Liu
Controlling surface states using different functional groups is an effective and facile way to modulate the fluorescence of carbon dots (CDs), but the underlying mechanisms are still unclear and urgent to solve. In this work, we synthesized red emitting CDs and achieved multiple emission states (red, green and blue emission) by tailoring the surface states with different amino groups. In particular, the luminescence mechanism and the role of surface states were studied in detail. It is found that the multiple emission states are related to the speciation of nitrogen (pyridinic N, pyrrolic N, graphitic N and amino N) on the surface of CDs, of which the fluorophore formed by the deformation of p-phenylenediamine contributes to the red emission, pyridinic N is responsible for the green emission state, and pyrrolic N enhances the blue emission. A possible energy level diagram was proposed to disclose the electron transition process and relative levels induced by different surface groups on CDs. In addition, the modulated CDs with multiple emission states can be used as single light converters to fabricate a white light-emitting diode, which has white light color coordinates of (0.31, 0.32), a high color rendering index (CRI) of 85, a luminous efficiency of 8.8 lm W−1 and good stability.
研究领域:
材料科学
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光学工程
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DOI
高影响因子
Nanomaterials
·
2019
·Vol. 9
·期 4
·529
·
IF 4.034
Kai Jiang,Xiangyu Feng,Xiaolu Gao,Yuhui Wang,Congzhong Cai,Zhongjun Li,Hengwei Lin
The achievements of multicolor photoluminescent (PL)-emissive carbon dots (CDs), particularly red to near infrared (NIR), are critical for their applications in optoelectronic devices and bioimaging, but it still faces great challenges to date. In this study, PL emission red-shifts were observed when tartaric acid (TA) was added into m-phenylenediamine (mPD) or o-phenylenediamine (oPD) solutions as carbon sources to prepare CDs, i.e., from blue to green for mPD and from yellow-green to red for oPD. Morphology and structure analyses revealed that the increased surface oxidation and carboxylation were responsible for the red-shifts of emission, indicating that TA played a key role in tuning the surface state of CDs. These factors could be employed as effective strategies to adjust PL emissions of CDs. Consequently, multicolor PL CDs (i.e., blue-, green-, yellow-green- and red-emissive CDs) can be facilely prepared using mPD and oPD in the absence and presence of TA. Particularly, the obtained red-emissive CDs showed a high PL quantum yield up to 22.0% and an emission covering red to NIR regions, demonstrating great potentials in optoelectronic devices and bioimaging. Moreover, multicolor phosphors were further prepared by mixing corresponding CDs with polyvinylpyrrolidone (PVP), among which the blue, green, and red ones could serve as three primary color phosphors for fabricating multicolor and white light-emitting diodes (LEDs). The white LED was measured to show a Commission Internationale de L’Eclairage (CIE) 1931 chromaticity coordinate of (0.34, 0.32), a high color rendering index (CRI) of 89, and a correlated color temperature (CCT) of 5850 K, representing one of the best performances of white LEDs based on CDs.Keywords:carbon dots;multicolor photoluminescence;surface state;light-emitting diodes
研究领域:
材料科学
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光学工程
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生物医学工程
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DOI
PubMed
高影响因子
Nanomaterials
·
2019
·Vol. 9
·期 11
·1556
·
IF 4.034
Dan Zhao,Xuemei Liu,Zhixia Zhang,Rui Zhang,Liangxiu Liao,Xincai Xiao,Han Cheng
The adjustment of the emitting wavelength of carbon dots (CDs) is usually realized by changing the raw materials, reaction temperature, or time. This paper reported the effective synthesis of multicolor photoluminescent CDs only by changing the solvent in a one-step solvothermal method, with 1,2,4,5-tetraaminobenzene as both the novel carbon source and nitrogen source. The emission wavelengths of the as-prepared CDs ranged from 527 to 605 nm, with quantum yields (QYs) reaching 10.0% to 47.6%, and it was successfully employed as fluorescence ink. The prepared red-emitting CDs (R-CDs, λem= 605 nm) and yellow-emitting CDs (Y-CDs, λem= 543 nm) were compared through multiple characterization methods, and their luminescence mechanism was studied. It was discovered that the large particle size, the existence of graphite Ns, and oxygen-containing functional groups are beneficial to the formation of long wavelength-emitting CDs. Y-CDs responded to crystal violet, and its fluorescence could be quenched. This phenomenon was thus employed to develop a detection method for crystal violet with a linear range from 0.1 to 11 µM and a detection limit of 20 nM.Keywords:carbon dots;multicolor luminescence;solvent control;surface state;crystal violet sensing
研究领域:
材料科学
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化学
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产品关联
DOI
PubMed
高影响因子
Materials Today Energy
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2022
·
IF 9.257
Jialong Li,Xiaoxu Liu,Jiangdong Gu,Dongyang Chen,Yu Feng,Wenchao Zhang,Dong Yue,Yanpeng Li,Congcong Zhu,Shaodong Li,Shaohui Huang,Xiaofeng Wang
Polymer-based materials play a crucial role in progressive electronic devices and electric power systems due to their excellent ferroelectric and dielectric performances. High ferroelectricity of the polymers could be achieved even at a low electric field with ferroelectric nanofillers introduced. However, the origin of the extra ferroelectricity enhancements of these composites besides the intrinsic ferroelectricity of fillers are still ambiguous. Herein, the Ca 2 Nb 3 O 10 (CNO) nanosheets were selected as ferroelectric nanofillers, which were embedded into the polyvinylidene fluoride (PVDF)-based polymer matrix . Numerous characterization results manifested that the surface of ferroelectric nanofillers could induce the formation of polar-oriented amorphous fractions (OAFs) in the composites. Experimental results indicated these formed OAFs are the origination of the enhanced ferroelectricity of the composites. In contrast, the aluminum oxide layer was constructed onto the CNO surface to cut off the interaction between the CNO nanosheets and the polymer matrix. These effects could be eliminated when the direct contact between the nanofiller and polymer matrix is interrupted, which facilitates the energy storage performance enhancements of the composites. This work reveals the origin of the extra ferroelectricity enhancements of polymer-based composites containing ferroelectric nanofillers. It may blaze new trails in realizing multifunctional applications of polymer-based composites via surface engineering.
研究领域:
材料科学
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电子工程
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DOI
高影响因子
Small
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2022
·Vol. 19
·期 31
·2204158
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IF 15.153
Bohan Zhang,Bingzhe Wang,Elena V. Ushakova,Bingchen He,Guichuan Xing,Zikang Tang,Andrey L. Rogach,Songnan Qu
It is important to reveal the luminescence mechanisms of carbon dots (CDs). Herein, CDs with two types of optical centers are synthesized from citric acid in formamide by a solvothermal method, and show high photoluminescence quantum yield reaching 42%. Their green/yellow emission exhibits pronounced vibrational structure and high resistance toward photobleaching, while broad red photoluminescence is sensitive to solvents, temperature, and UV–IR. Under UV–IR, the red emission is gradually bleached due to the photoinduced dehydration of the deprotonated surface of CDs in dimethyl sulfoxide, while this process is hindered in water. From the analysis of steady-state and time-resolved photoluminescence and transient absorption data together with density functional theory calculations, the green/ yellow emission is assigned to conjugated sp 2 -domains (core state) similar to organic dye derivatives stacked within disk-shaped CDs; and the broad red emission—to oxygen-containing groups bound to sp 2 -domains (surface state), whereas energy transfer from the core to the surface state can happen.
研究领域:
材料科学
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光学
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理论化学
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DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2024
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IF 9.4
Hangzhen Zhang,Jiafan Bai,Xiangli Chen,Linyu Wang,Wenzhen Peng,Yuancong Zhao,Jie Weng,Wei Zhi,Jianxin Wang
Carbon dots have shown a broad application prospect in the fields of sensing and detection, biological imaging, and optoelectronic devices. However, it is still challenging to adopt a simple and green synthesis route and to develop new precursor systems to prepare full-color luminescent carbon dots. This study proposes a mechanism for fine regulation of carbon dot fluorescence spectra based on surface states of C N, C O C, and O H, among which C N play a major role in long wavelength emission while C O C and O H are responsible for the blue shift of emission wavelength. Using 4,4-bipyridine and p-phenylenediamine as precursors in safe and environmentally friendly glycol and water as solvents for the first time, the fine spectral carbon dots with full spectrum luminescence from purple (441 nm) to red (627 nm) were successfully synthesized by simply changing the composition of the reaction solvent and using a short reaction time. Compared with other reports on regulating polychromatic carbon dots, our method is more refined and has a wider distribution of luminescent colors. In addition, the obtained carbon dots based on such surface state luminescence mechanism have shown good application prospects in specific detection of Fe 3+ and cell labeling.
研究领域:
材料科学
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光学
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生物医学工程
✓ 已验证
DOI
PubMed
高影响因子
Small
·
2019
·Vol. 15
·期 48
·1901550
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IF 10.856
Ruina Wang,Haishan Wu,Rui Chen,Yuwu Chi
Carbon nanotubes (CNTs) as well-known nanomaterials are extensively studied and widely applied in various fields. Nitric acid (HNO 3 ) is often used to treat CNTs for purification purposes and preparing oxidized CNTs for various applications. However, too little attention is paid to investigating the effect of HNO 3 treatment on the optical properties of CNTs. In this work, it is observed for the first time that HNO 3 -oxidized multiwalled carbon nanotubes (ox-MWCNTs) have strong electrochemiluminescence (ECL) activity, which enables ox-MWCNTs to become new and good ECL carbon nanomaterials after carbon quantum dots (CQDs) and graphene quantum dots (GQDs). Various characterization technologies, such as transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy, are used to reveal the relationship between ECL activity and surface states. The ECL behaviors of ox-MWCNTs are investigated in detail and a possible ECL mechanism is proposed. Finally, the new ECL nanomaterials of ox-MWCNTs are envisioned to have promising applications in sensitive ECL sensing and in the study of CNT-based catalysts.
研究领域:
材料科学
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分析化学
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纳米技术
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF LUMINESCENCE
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2021
·
IF 3.599
Yaoyao Yang,Kangliang Peng,Yakun Deng,Youjun Zhao,Jinshui Ai,Xiao Min,Mengzhu Hu,Shuai Huang,Lixin Yu
carbon quantum dots (CQDs) have been widely studied due to their outstanding merits. In this article, it is important and interesting that the full-color-emission (blue, green and red light) CQDs are successfully obtained by a simple one step method. They are synthesized from two common precursors, m-phenylenediamines and phosphorus acid, using a one pot solvent engineering strategy. These CQDs can emit bright and stable light under a single-wavelength UV light . Moreover, the alterations of photoluminescence (PL) emission of the blue, green, red are ascribed to the surface states but not the particle size. The redshifted emission of the three CQDs samples is tentatively proposed to result from the contents of sp 2 -hybridized domains, surface C O and the pyridinic N.
研究领域:
材料科学
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光学
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化学
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DOI
高影响因子
npj Quantum Materials
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2024
·Vol. 9
·期 1
·1-8
·
IF 5.4
Liu Xiang-Rui,Zhu Ming-Yuan,Feng Yuanwen,Zeng Meng,Ma Xiao-Ming,Hao Yu-Jie,Dai Yue,Luo Rong-Hao,Zhu Yu-Peng,Yamagami Kohei,Liu Yi,Cui Shengtao,Sun Zhe,Liu Jia-Yu,Huang Yu,Liu Zhengtai,Ye Mao,Shen Dawei,Li Bing,Liu Chang
Obstructed atomic insulator is recently proposed as an unconventional material, in which electric charge centers localized at sites away from the atoms. A half-filling surface state would emerge at specific interfaces cutting through these charge centers and avoid intersecting any atoms. In this article, we utilized photoemission spectroscopy and density functional theory calculations to study one of the obstructed atomic insulator candidates, NiP 2 . A floating surface state with large effective mass that is close to the Fermi level and isolated from all bulk states is resolved on the (100) cleavage plane, implying better catalytic activity in this plane than the previously studied surfaces. Density functional theory calculation results elucidate that this floating surface state is originated from the obstructed Wannier charge centers, albeit underwent surface reconstruction. Our findings not only shed lights on the study of obstructed atomic insulators, but also provide possible route for development of new catalysts.
研究领域:
材料科学
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凝聚态物理
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DOI
高影响因子
Nanoscale Research Letters
·
2019
·Vol. 14
·期 1
·1-9
·
IF 3.159
Wei Xian,Mei Shiliang,Yang Dan,Zhang Guilin,Xie Fengxian,Zhang Wanlu,Guo Ruiqian
The tunable photoluminescence (PL) of nitrogen-doped carbon dots (NCDs) has attracted much attention in recent years while the specific mechanism is still in dispute. Herein, NCDs with yellow emission were successfully synthesized via a facile hydrothermal approach. Three kinds of post-treatment routes were investigated to verify the influence of surface states on the PL emission of NCDs including solvent-dependent, reduced-reaction and metal-enhanced effect. The interaction mechanism was studied by absorption spectrum, structural characterizations, steady-state and time-resolved spectroscopy. When dispersed in different solvents, the as-prepared NCDs show tunable emission and PL enhancement attributed to hydrogen bonding between solvents and NCDs. Besides, the addition of NaBH 4 can induce the reduction of the C=O bonds existing in original NCDs to C–O bonds and thus result in the enhancement of the intrinsic ( n – π *) emission. Moreover, metal-enhanced fluorescence of NCDs can also be observed when adding Ag + into initial NCD solution, which might be ascribed to aggregation-induced emission enhancement. These results for post-treated NCDs demonstrate that surface functional groups are responsible for PL emission and provide new possibilities like multi-image sensing and lighting application.
研究领域:
材料科学
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光化学
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产品关联
DOI
PubMed
高影响因子
Nanoscale
·
2018
·Vol. 10
·期 40
·19031-19038
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IF 7.233
Qiuhong Min,Lei Zhao,Yushuang Qi,Jing Lei,Wenbo Chen,Xuhui Xu,Dacheng Zhou,Jianbei Qiu,Xue Yu
An amorphous layer acting as a quenching center at the surface of oleic acid-capped NaGdF4:Yb3+/Tm3+ nanoparticles is observed directly, which can be reconstructed via a novel post-chemical annealing process. The amorphous phase of the surface layer of NaGdF4:Yb3+/Tm3+ nanoparticles gradually crystallizes as the post-chemical annealing temperature increases; meanwhile, the good dispersibility of the as-obtained nanoparticles is maintained. The reduction of surface defects and higher local symmetry of the crystal field environment around the doped rare-earth ions contribute to drastically increased up-conversion (UC) emission intensity of the NaGdF4:Yb3+/Tm3+ nanoparticles. In particular, the blue emission of Tm3+ at 450 nm enhances 10-fold after the post-chemical annealing process at 250 °C compared with the counterpart without further surface-state treatments. The color gamut of well-crystallized NaGdF4:Yb3+/Tm3+ with a modified surface covers the blue to yellow region in CIE chromaticity coordinates via a non-steady-state UC process. The results indicate that the surface states of these UC nanoparticles can be feasibly improved via the post-chemical annealing process without encouraging agglomeration, which further optimizes their UC properties for practical applications.
研究领域:
材料科学
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光学
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产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Lai Wei,Jing Li,Shuai Zhang,Yawen Zhou,Bo Li,Zhanwen Zhang
In this work, expanded graphite (EG) was dispersed inside modified polysiloxane resin and successfully printed various cellular structures with span feature via ultraviolet-thermal field co-assisted direct ink writing . The carbon-rich layer was in-situ deposited in the designed porous structure surface by no gas flow pyrolysis process. The characterization of Raman and X-ray photoelectron spectroscopy indicate that the deposited cladding structure possessed amounts of sp 2 -C, and mainly bonds to the matrix in the manner of Si–C. The presence of cladding structure played a vital role in enhancing the electric conductivity and interface polarization, resulting in excellent microwave absorption performance. The addition of expanded graphite also improved the dielectric property by reinforcing the internal interfacial polarization and achieving a good impedance matching. Finally, the structure reached a minimum reflection loss of −59.31 dB at the thickness of 2.8 mm, and a broadband absorption of 4.2 GHz in the X-band (8.2–12.4 GHz) at 3.1 mm, covering the whole X band. The novelty strategy of controlling the surface state by pyrolysis vapor self-deposition can open a new avenue to tailor the functional characteristic of materials, especially on the assist of direct ink writing which can easy realize complex structural geometry on-demand.
研究领域:
材料科学
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电子工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）