Scientific Reports
·
2016
·Vol. 6
·期 1
·1-10
·
IF 5.228
Zhang Jia,Zhao Chao,Liu Na,Zhang Huanxi,Liu Jingjing,Fu Yong Qing,Guo Bin,Wang Zhenlong,Lei Shengbin,Hu PingAn
Single–layer and mono–component doped graphene is a crucial platform for a better understanding of the relationship between its intrinsic electronic properties and atomic bonding configurations. Large–scale doped graphene films dominated with graphitic nitrogen (GG) or pyrrolic nitrogen (PG) were synthesized on Cu foils via a free radical reaction at growth temperatures of 230–300 °C and 400–600 °C, respectively. The bonding configurations of N atoms in the graphene lattices were controlled through reaction temperature and characterized using Raman spectroscopy, X–ray photoelectron spectroscopy and scanning tunneling microscope. The GG exhibited a strong n–type doping behavior, whereas the PG showed a weak n–type doping behavior. Electron mobilities of the GG and PG were in the range of 80.1–340 cm 2 V −1 ·s −1 and 59.3–160.6 cm 2 V −1 ·s −1 , respectively. The enhanced doping effect caused by graphitic nitrogen in the GG produced an asymmetry electron–hole transport characteristic, indicating that the long–range scattering (ionized impurities) plays an important role in determining the carrier transport behavior. Analysis of temperature dependent conductance showed that the carrier transport mechanism in the GG was thermal excitation, whereas that in the PG, was a combination of thermal excitation and variable range hopping.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
PubMed
高影响因子
Journal of Materials Chemistry A
·
2024
·
IF 10.7
Channa Wang,Fuzhu Liu,Mingjin Du,Mi Zhang,Xiangdong Ding,Changsheng Xiang
Identical fluorescent emission in carbon dots (CDs) is crucial for applications such as anti-counterfeiting which requires precise spectrum control. However, the optical properties of CDs are highly sensitive to reaction conditions, which complicate their consistency. In this study, nitrogen-doped CDs (N-CDs) were synthesized using a single precursor (2,4-dihydroxypyridine) under different conditions, all exhibiting identical blue fluorescence, regardless of size and reaction parameters. X-ray photoelectron spectroscopy (XPS) and elemental analysis confirmed a high concentration of graphitic and pyridinic nitrogen in the N-CDs. Density functional theory (DFT) calculations were employed to explore the influence of these nitrogen species on the optical properties of the N-CDs. The results demonstrated that graphitic nitrogen plays a pivotal role in size-independent emission by disrupting the conjugated sp2-carbon domains, effectively eliminating the quantum confinement effect. This study offers new insights into the role of graphitic nitrogen in band gap engineering and the fluorescence mechanism of CDs, revealing a path to achieve CDs with identical fluorescent emission. The stable and reproducible emission under various reaction conditions positions these N-CDs as ideal candidates for large-scale production of blue CDs, minimizing the need for complex purification processes. Furthermore, N-CDs were modified with urea to enhance hydrophilicity, making them suitable for use as markers in aqueous products. The resulting hydrogen-bond-enhanced reticulated structure also endowed the material with room-temperature phosphorescence (RTP) properties. This innovation grants N-CDs substantial potential for anti-counterfeiting applications across various media.
研究领域:
材料科学
·
光学
·
化学工程
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2021
·Vol. 45
·期 28
·12669-12677
·
IF 3.591
Yu Jiang,Chen Yang,Qian Yao,Yurong Deng,Jingjing Yang,Yanjun Liu,Zhuozhi Ouyang,Weilin Huang,Zhi Dang
To clarify the function of the nitrogen-containing structures on the adsorption of heavy metals, nitrogen-enriched biochars (NBCs) mainly composed of pyrrolic, pyridinic, and graphitic nitrogen were prepared to investigate the interaction mechanism with Cd(II). The results of batch experiments revealed that the saturated Cd(II) adsorption capacities of Pr-NBC, Pd-NBC, and Gp-NBC were 12.68, 24.04, and 35.95 mg g−1 respectively. The strongest adsorption ability was found for the Gp-NBC and was ascribed to the enhancement of graphitic nitrogen. The results from SEM-EDS and XRD, and the zeta potentials for the materials revealed that carbonate precipitation, cation exchange, and electrostatic interactions contributed to the adsorption of Cd(II). XPS and FTIR demonstrated that nitrogen in the carbon framework might have promoted the adsorption by forming cation–π interactions between graphitic nitrogen and Cd(II). The electrostatic potential distribution of the nitrogen with different configurations fully confirmed this. The theoretical calculations also proved that graphitic nitrogen had the lowest interaction energy to Cd(II), which further verified the strong contribution of graphitic nitrogen to the adsorption of heavy metal. Nitrogen-enriched biochar effectively adsorbs, changes the migration process of heavy metals in the natural environment, and thus alleviates the current situation of heavy metal pollution.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2019
·
IF 5.383
Haoqing Ji,Mengfan Wang,Sisi Liu,He Sun,Jie Liu,Tao Qian,Chenglin Yan
Pyridinic and graphitic nitrogen are recognized as the most promising dopants for promoting oxygen reactions since they are beneficial to the formation of corresponding C–N bonds as efficient active sites. However, complete control of such efficient nitrogen-doping sites in carbon materials is difficult to realize in practice in a pyrolysis process . Here, we present maximized pyridinic and graphitic nitrogen-doped oxygen electrode via the precise use of nitrogen-containing precursors and carbonization temperature. The critical roles of pyridinic and graphitic nitrogen dopants in enhancing oxygen reaction activity are unraveled and this highly active material exhibits a remarkable half-wave potential of 0.89 V versus the reversible hydrogen electrode (vs. RHE) for oxygen reduction reaction (ORR) and a small potential gap of 0.78 V between ORR and oxygen evolution reaction (OER) in 0.1 M KOH, which is one of the best to date among metal-free bifunctional electrocatalysts . Both zinc-air batteries using liquid electrolytes and the all-solid-state batteries assembled with such air cathodes exhibit excellent cycle performance and reversibility, which can be expressly observed by in-situ X-ray diffraction (XRD) characterization. This nitrogen dopants engineering strategy gives an effective methodology to make full use of nanocarbon materials for their practical applications in next-generation powerful and durable energy devices.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Yan Gu,Tiefeng Xu,Xiufang Chen,Wenxing Chen,Wangyang Lu
Single-atom catalysts (SACs) have become an attractive concept in heterogeneous catalysis because of its high activity, selectivity and maximized utilization efficiency. However, constructing a high-loading SACs through conventional pyrolysis methods remains a challenge, because metal precursors usually have low thermal stability and the decrease of particle size will lead to an increase of surface energy. Herein, we used dicyandiamide to tailor the metatungstate and fix the W atoms during the thermal polymerization process, finally obtained a new kind of W-SAC (single W atoms anchored on graphitic carbon nitride, named as W-CN) with a high-loading of 11.16 wt% and a unique O, N coordination. The electrospray ionization high-definition mass spectrometry (ESI-HDMS) revealed that single W atoms were introduced into graphitic carbon nitride via the polycondense of W-containing dicyandiamide intermediate. The unique atomically dispersed N-W-O 3 moieties, which promoted the separation efficiency of photogenerated electron-hole pairs, were identified by Aberration-corrected scanning transmission electron microscopy (AC-TEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure spectroscopy (XAFS) and Density functional theory (DFT) calculation. Moreover, compared to pure CN, the W-CN exhibited an enhanced catalytic performance for the oxidation of carbamazepine (CBZ) under solar light irradiation. The experiment results revealed that photogenerated holes (h + ), superoxide radicals (•O 2 − ), and singlet oxygen ( 1 O 2 ) were the predominant active species and played an important role in eliminating emerging contaminants. This work paves a facile and efficient path toward high-loading SAC, and opens new insight into tracking SAC structure evolution.
研究领域:
化学
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2017
·
IF 6.844
Siyu Tan,Zipeng Xing,Jiaqi Zhang,Zhenzi Li,Xiaoyan Wu,Jiayi Cui,Junyan Kuang,Qi Zhu,Wei Zhou
Ti 3+ self-doped TiO 2 /g-C 3 N 4 mesostructured nanosheets heterojunctions (Ti 3+ -TiO 2 /Meso-g-C 3 N 4 ) have been prepared via calcination-sonication assisted method using amino cyanamide as precursors, combined with a solid-state chemical reduction method. The Ti 3+ -TiO 2 /Meso-g-C 3 N 4 heterojunctions with narrow band gap of ∼2.21 eV possess relative high surface area of ∼73.8 m 2 g −1 , and large pore size of ∼10 nm. Remarkably, the Ti 3+ -TiO 2 /Meso-g-C 3 N 4 heterojunctions exhibit excellent visible-light-driven photocatalytic activity for degradating phenol in wastewaters. The photocatalytic hydrogen production rate of Ti 3+ -TiO 2 /Meso-g-C 3 N 4 heterojunctions rise to ∼290.2 μmol h −1 g −1 , which is about 4 and 14 times higher than that of the bare Meso-g-C 3 N 4 and TiO 2 , respectively. The enhanced photocatalytic activity may be ascribed to the synergetic effect of the mesoporous structure providing sufficient surface active sites, and Ti 3+ self-doping and the formed heterojunctions promoting the spatial separation of photogenerated electron-hole pairs.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2024
·
IF 14
Na Li,Tingting Ma,Huihui Wang,Jiayi Li,Dingrong Qiu,Zhen Meng,Jiangdu Huang,Lijun Sui,Faming Han,Huidan Lu,Yongping Liu,Sundaram Chandrasekaran
Rational design of defected carbons adjacent to nitrogen (N) dopants is a fascinating but challenging approach for enhancing the catalytic performance of N-doped carbon. Meanwhile, the combined effect of heteroatom doping and defect engineering can efficiently increase the oxygen reduction reaction (ORR) ability of inactive carbons through charge redistribution. Herein, we report that an enhanced built-in electric field caused by the combined effect of N-doping and carbon defects in the two-dimensional (2D) mesoporous N-doped carbon nanoflakes (NCNF) is a promising technique for improving ORR performance. As a result, the NCNF exhibits more promising ORR activity than Pt/C and similar performance with reported robust catalysts. Comprehensive experimental and theoretical investigations suggest that topologically defected carbon adjacent to the graphitic valley nitrogen is a real active site, rendering optimal energy for the adsorption of ORR intermediates and lowering the total energy barrier for ORR. Also, NCNF-based Zn-air batteries exhibited an excellent power density and specific capacity of ∼121.10 mW cm −2 and ∼679.86 mA h g Zn −1 , respectively. This study not only offers new insights into defected carbons with graphitic valley N for ORR but also proposes novel catalyst design principles and provides a solid grasp of the built-in electric field effect on the ORR performance of defective catalysts.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Yunpeng Zha,Xiaoxiao Sun,Zhengjun Xiong,Dandan Dong,Shili Li,Qinqin Wang,Minmin Liu
The porous carbon materials co-coordinated with Fe and N (Fe-N-C) were successfully synthesized through one-step pyrolysis with the zeolitic imidazolate framework (ZIF-8) as the precursor. Through systematic optimization of iron ion concentration during synthesis, the Fe-N-C-20 specimen exhibited optimal adsorption performance toward dibenzothiophene (DBT), demonstrating a maximum sulfur adsorption capacity of 22.14 mg S/g with a corresponding removal efficiency of 92 %. This superior performance can be primarily ascribed to the formation of Fe-S bonds anchored on Fe-N active sites, N-S interactions mediated by graphitic nitrogen species and appropriate pore size that allows access to thiophenic compounds. Furthermore, the experimental adsorption isotherms for DBT exhibited strong correlation with the Density Functional Theory (DFT) calculation. Additionally, the material's adsorption process followed pseudo-second-order kinetics and Langmuir isotherms of Fe-N-C, and the pseudo-second-order model shows the smallest RMSE (0.66), extremely low SSE (3.03) and AIC (-1.86), which further proves its excellent fitting ability. And the best balance between parameter efficiency and fitting performance. The high stability and recyclability of ZIF-derived Fe-N-C porous adsorbents contribute to sustainable industrial practices.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Qi Zhang,Zhen Zhang,Bowen Li,Tingfeng Shan,Linzhi Shen,Yaming Zhou,Guanghua Tang,Hongmin Yang
Phase change materials (PCM) have attracted much attention in the field of thermal energy storage because of exceptional heat storage capacity, stable operating temperature, and recyclability . However, organic phase change materials , represented by palmitic acid (PA), are limited by inherent leakage problem, unsatisfactory thermal responsiveness and inefficient photo-thermal storage capacity, which severely hamper the development of PCMs technology. As a means of addressing these challenges, we developed one novel support material with 2D/0D structure for palmitic acid via thermal polymerization , specifically, in which highly dispersed Ag quantum dots (Ag QDs) was firmly anchored on graphitic carbon nitride (g-C 3 N 4 ). PA was further infiltrated into the layered structure of nanoporous g-C 3 N 4 /Ag QDs to successfully synthesize novel shape-stabilized PA/g-C 3 N 4 /Ag QDs composite phase change materials (CPCM). On the one hand, benefiting from the tightly stacked porous structure of g-C 3 N 4 /Ag QDs, PA is effectively encapsulated to avoid leakage problem during the solid-liquid transition with a superior adsorption capacity up to 65 %. On the other hand, the combination of g-C 3 N 4 and Ag QDs in PA/g-C 3 N 4 /Ag QDs CPCM demonstrated a synergistic effect resulting in faster heat transfer capability and more efficient solar energy capture capability compared to pure PA, which is capable of dual utilization of heat and solar energy. The newly developed PA/g-C 3 N 4 /Ag QDs CPCM features a high melting latent heat and an appropriate phase change temperature , which are 128.35 J/g and 61.92 °C, respectively. The corresponding solidification enthalpy and temperature are 121.70 J/g and 60.02 °C. The photo-thermal conversion efficiency of the material is improved to 78.6 %, facilitating a rapid capture and storage of solar energy. Furthermore, through the optimization of the preparation process, Ag QDs are densely anchored on the surface of g-C 3 N 4 , which retains the excellent properties of metallic silver while eliminates the metal agglomeration phenomenon after repeated utilization of CPCMs. PA/g-C 3 N 4 /Ag QDs CPCM is proved to be extremely recyclable and thermally stable after massive thermal cycles. This innovative and operational encapsulation modified method significantly optimizes the practicality of phase change materials. The obtained shape-stabilized PA/g-C 3 N 4 /Ag QDs CPCM is more versatile, and its unique comprehensive properties can provide high-quality materials for photo-thermal storage systems.
研究领域:
材料科学
·
能源技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2019
·Vol. 19
·期 7
·4020-4025
·
IF 1.093
Song Bing Bing,Zhen Yi Fan,Yin Hao Yong,Song Xu Chun
In this work, platinum nanoparticles were modified on graphite-like carbon nitride (g-C3N4) surface via a simple one-pot deposition reduction method, and the prepared Pt/g-C3N4 was used as electrode materials for phenol sensing. The morphology
and crystallographic structure of Pt/g-C3N4 were characterized by Scanning transmission electron microscope (STEM) and X-ray diffraction (XRD). The electrochemical performance of Pt/g-C3N4 toward phenol was investigated in details and the results
showed that the Pt/g-C3N4 sensor had favorable sensing ability for phenol detection. Under the optimum parameters, the electrochemical sensor had a wide range of 2 to 20 µM, lower detection limits of 0.667 µM (S/N═3), and higher sensitivity
of 1.21084 mA µM−1 in phenol detection, indicating the excellent capability of the newly developed sensor to determine phenol. Moreover, the design of the Pt/g-C3N4 sensor may provide a potential material for actual application in phenol
detection due to its merits of simplicity, reliability, sensitivity and low-cost.
研究领域:
材料科学
·
环境科学
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 24
·19665-19670
·
IF 3.201
Xiangyu Lu,Dan Wang,Liping Ge,Lihui Xiao,Haiyan Zhang,Lilai Liu,Jinqiu Zhang,Maozhong An,Peixia Yang
Nitrogen-doped graphene (N-G) is considered as a promising catalyst for the oxygen reduction reaction (ORR). However, the contributions of pyridinic N, pyrrolic N and graphitic N in N-G for the ORR catalytic activity are controversial. In this work, the contents of pyridinic N, pyrrolic N and graphitic N in N-G were transformed by annealing at different temperatures. It is found that the total N content in N-G is not the critical factor to determine the ORR activity. An increase in the annealing temperature can enhance the content of graphitic N in N-G, causing an improved catalytic ORR activity, which confirms that graphitic N is the active component. Moreover, the enriched graphitic N in the N-G-1000 catalyst shows a half-wave potential (E1/2) of 0.862 V, 29 mV higher than that of the commercial Pt/C catalyst (0.833 V), which is one of the best reported for ORR metal-free catalysts.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
Carbon Energy
·
2022
·Vol. 5
·期 2
·e257
·
IF 21.556
Yihua Tang,Jingjing Chen,Zhiyong Mao,Christina Roth,Dajian Wang
N-doped carbons as one of the most prominent anode materials to replace standard graphite exhibit outstanding Li + storage performance. However, N-doped carbon anodes still suffer from low N-doping levels and low initial Coulombic efficiency (ICE). In this study, high N-doped and low graphitic-N carbons (LGNCs) with enhanced ICE were synthesized by taking advantage of a denitrification strategy for graphitic carbon nitride (g-C 3 N 4 ). In brief, more than 14.5 at% of N from g-C 3 N 4 (55.1 at% N) was retained by reacting graphitic-N with lithium, which was subsequently removed. As graphitic-N is largely responsible for the irreversible capacity, the anode's performance was significantly increased. Compared to general N-doped carbons with high graphitic-N proportion (>50%) and low N content (<15 at%), LGNCs delivered a low proportion of 10.8%–17.2% within the high N-doping content of 14.5–42.7 at%, leading to an enhanced specific capacity of 1499.9 mAh g −1 at an ICE of 93.7% for the optimal sample of LGNC (4:1). This study provides a facile strategy to control the N content and speciation, achieving both high Li + storage capacity and high ICE, and thus promoting research and application of N-doped carbon materials.
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
危险品化学品经营许可证（带存储）