PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 26
·期 4
·3263-3273
·
IF 3.3
Ziwei Zhai,Bofeng Zhang,Yutong Wang,Guozhu Liu
Based on the disturbance of electronic density, nitrogen-doped nanocarbons show promising properties to anchor metal clusters. However, precisely regulating the coordination mode between N species and the active site remains challenging. Herein, we rationally designed three N types (graphitic N, pyridinic N and pyrrolic N) in nanocarbons to anchor Pt clusters for the benchmark propane dehydrogenation. The specific activity of the pyridinic-N-doped catalyst was 147.54 molC3H6 molPt−1 h−1 at 550 °C, which was 1.3 times higher than those of graphitic- and pyrrolic-N-doped catalysts. Unlike the regular tetrahedron Pt cluster in the graphitic-N catalyst or the distorted three-layered Pt cluster in the pyrrolic-N catalyst, the Pt cluster in the pyridinic-N catalyst was an inverted tetrahedron, which increased the contact degree without geometric repulsion towards C–H bond scission. The geometric parameters of detached H and C atoms in the methylene group for the pyridinic N catalyst was decreased to strengthen the C–H bond scission. After CH3CHCH3* adsorption, the Bader charge of the Pt active site also became highly positive, which tailored the d-band center closer to the Fermi level and provided more vacant orbitals for C–H bond breakage. Therefore, pyridinic N in nanocarbons is promising to anchor small-sized Pt for alkane dehydrogenation in terms of geometric and electronic effects.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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
ELECTROCHIMICA ACTA
·
2020
·
IF 6.215
Hui Jiang,Lin Liu,Kai Zhao,Zhen Liu,Xinsheng Zhang,Shuozhen Hu
Nitrogen doping was widely used to increase the electronic density of carbon materials and to enhance the adsorption of the supported metal catalysts . However, the exact interaction between various doped nitrogen species and palladium (Pd) have rarely been reported for formic acid electrooxidation (FAO). In this study, the effect of the doped pyridinic-N and pyrrolic-N on the electronic structure and the electrochemical activity of Pd toward FAO are investigated. The oxidation state of Pd is reduced and more metallic Pd is formed when Pd nanoparticles supported on pyridinic-N and pyrrolic-N doped carbon materials . Density functional theory (DFT) calculations simulate that the adsorption energy of HCOO* and *COOH on Pd/pyrrolic-N are lower than those on Pd/pyridinic-N. Both DFT and electrochemical measurements suggest that the FAO activity of Pd is more correlated with the pyrrolic-N than pyridinic-N. The catalyst contains more pyrrolic-N species exhibits higher electrochemical activity and faster kinetics for FAO reaction. Moreover, Pd 2+ -N complexes are formed in all the nitrogen doped catalysts and display good activity for FAO. In this study, Pd supported on urea treated carbon (Pd/UR) owns the highest content of pyrrolic-N and exhibits the best activity for FAO.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
·
IF 10.753
Yueqi Li,Minjuan Cai,Bingbing Ji,Feng Wu,Li-Zhi Huang
Carbonous materials were found to catalyze the dechlorination of trichloroethylene (TCE) by green rust (GR), but the catalytic mechanism was not fully understood. We have developed a facile ball milling method to synthesize N-doped graphene (NG) with various N species, catalyzing fast dechlorination of TCE to acetylene by GR with the highest acetylene production rate of ~0.1 d −1 . The adsorption of TCE onto NG is mainly derived from the graphene region of NG, and high pyridinic N is essential for the enhanced TCE reduction by GR. Oxygen species did not enhance the TCE reduction in GR/NG system. High dechlorination rates are correlated to a high amount of defect in NG and a high electron conductivity of NG. Pyridinic N has the highest adsorption energy for TCE among all the N species, which leads to the highest catalytic performance. High electrochemically active surface area resulted from the high content of pyridinic N facilitate the NG-catalyzed dechlorination. The acetylene production rate in real groundwater is still around one-third of that in ultrapure water. This work not only reveals the catalytic mechanism of NG-catalyzed dechlorination by GR, but also provide a feasible approach for practical remediations of TCE-contaminated groundwater using GR-NG mixture.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Today Sustainability
·
2022
·
IF 7.244
Y. Liu,H. Liu,L. Tian,L. Pang,X. Liu,J. Li
As a most promising potential next-generation energy storage system , lithium-sulfur batteries (Li–S batteries) received great attention in recent years. However, how to effectively prevent the shuttling effect and accelerate the redox reaction kinetics of polysulfides are still a challenge. Herein, a strategy of using the soft template as a pore-forming agent was proposed to prepare Mo 2 C/nitrogen-doped carbon hollow microflowers (marked as H–Mo 2 C/NC MFs), which was used as an efficient absorbent and electrocatalyst of polysulfides for Li–S batteries. Due to the physical limitations of assembling the special nanosheet into a hollow carbon matrix in the shape of a microflower, the H–Mo 2 C/NC MFs can be used as an appropriate S loading substrate. With the synergistic chemisorption from pyridine N sites and high content polar Mo 2 C nanoparticles , the as-prepared H–Mo 2 C/NC MFs can provide enhancing adsorption and catalytic conversion for polysulfides. As a result, the H–Mo 2 C/NC/S MFs-based cathode provides a high initial discharge capacity of 1104.8mAh/g at 0.2C. Even at the high rate of 1.0C, the initial capacity of 705.2mAh/g still shows good electrochemical performance, and in 1000 cycles, the average capacity decay rate is only 0.016%, with supercycle stability. This article provided a new strategy for a novel viewpoint for the reasonable design of conductive and polar materials for efficient and durable Li–S batteries.
研究领域:
能源材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2018
·Vol. 11
·期 1
·159
·
IF 2.467
Liqing Li,Xiancheng Ma,Ruofei Chen,Chunhao Wang,Mingming Lu
Nitrogen-doped porous carbon (ZC) is prepared by modification with ammonia for increasing the specific surface area and surface polarity after carbonization of zeolite imidazole framework-8 (ZIF-8). The structure and properties of these ZCs were characterized by Transmission electron microscopy, X-ray diffraction, N2sorption, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Through static adsorption tests of these carbons, the sample obtained at 600 °C was selected as an excellent adsorbent, which exhibited an excellent acetone capacity of 417.2 mg g−1(25 °C) with a very large surface area and high-level nitrogen doping (13.55%). The microporosity, surface area and N-containing groups of the materials, pyrrolic-N, pyridinic-N, and oxidized-N groups in particular, were found to be the determining factors for acetone adsorption by means of molecular simulation with density functional theory. These findings indicate that N-doped microporous carbon materials are potential promising adsorbents for acetone.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Jing Wang,Sisi Fan,Hongmin Duan,Jinming Xu,Yanqiang Huang
Carbon spheres with hierarchical pore structure were successfully synthesized by using strongly basic anion exchange resins exchanged with silicate, followed by pyrolysis in an inert atmosphere and etching silica. As a result of the quaternary ammonium group in the anion exchange resin structure, these carbon spheres were doped with nitrogen. The performance of these carbon spheres in the catalytic dehydrochlorination of 1,2-dichloroethane (EDC) was improved with the increase of calcination temperature, and the carbon sphere 900-900-RC showed the highest conversion rate (96.7%) and a selectivity to vinyl chloride above 99%. The structural and surface properties of N-doped carbon spheres were characterized by scanning electron microscopy, nitrogen sorption, and Raman and X-ray photoelectron spectroscopy. The result of these characterizations further verified that the quaternary nitrogen species are as effective as pyridine nitrogen species in this catalyst.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Energy Technology
·
2021
·Vol. 9
·期 8
·2100205
·
IF 3.631
Zipeng Zeng,Aya Gomaa Abdelkader Mohamed,Xiang Zhang,Yaobing Wang
Although metal–N-doped carbons are promising electrocatalysts for CO 2 -to-CO conversion due to their high conversion efficiency and current density, their commercial application is still challenging due to their narrow potential/current range. In general, a wide potential/current electrocatalyst is in high demand for industrial CO 2 electrocatalysis. Controllable strategy to tune N configurations toward pyridinic-enriched metal–N x active sites is attractive. The synergetic effect of the ability of pyridinic N to capture Lewis acidic CO 2 and the characteristics of Ni–N active sites to inhibit the hydrogen evolution reaction (HER) can achieve a wide potential window, which has high practical value. Herein, the well-chosen precursors resulting in a pyridinic-enriched Ni–N x site can selectively catalyze CO 2 toward CO generation in aqueous media with a high Faradaic efficiency (FE) of 100% with an overpotential of 680 mV. Continuous CO FE > 90% was recorded under a wide range of potentials without decay. Motivated by its practical characteristics in CO 2 electrocatalysts, a Zn–CO 2 battery is assembled achieving a CO 2 –CO conversion efficiency of more than 90% in a wide discharge current window. Therefore, the results highlight that pyridinic-enriched Ni–N x holds great promise as simultaneous CO-selective electrocatalyst by suitably tuning M–N configurations as new perspective strategy.
研究领域:
材料科学
·
电化学
·
能源转换
✓ 已验证
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
ENVIRONMENTAL POLLUTION
·
2021
·
IF 8.071
Na Liu,Qing Hu,Chao Wang,Lizhi Tong,Chih-Huang Weng,Longzhen Ding
This study demonstrated that nitrogen-doped carbon materials (NCMs) could effectively catalyze the chlorine elimination process in hexachloroethane (HCA) declorination in sulfide-containing environments for the first time. The k obs values of HCA dechlorination by sulfide in the presence of 10 mg/L NCMs were higher than that of no mediator at pH 7.3 by one or two orders of magnitude. The catalytic capabilities of NCMs on HCA dechlorination were evident in common ranges of natural pH (5.3–8.9) and it could be accelerated by the increase of pH but be suppressed by the presence of dissolved humic acid . Moreover, NCMs exhibited much better catalytic capability on HCA dechlorination compared to the carbon materials, mainly owing to the combined contributions of pyridine N, including enhanced nucleophilic attack to HCA molecule by generating newborn C–S–S and activation of HCA molecule by elongating C–Cl bonds. The functions of pyridine N in micron-sized NCMs with mesopores were better than in nano-sized NCMs on HCA dechlorination. These findings displayed the potential of NCMs, when released into sulfide-containing environments, may significantly increase the dechlorination of chlorinated aliphatic hydrocarbons.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanoscale
·
2017
·Vol. 9
·期 44
·17593-17600
·
IF 7.367
Min Wang,Xiangqian Fan,Lingxia Zhang,Jianjun Liu,Beizhou Wang,Ruolin Cheng,Mengli Li,Jianjian Tian,Jianlin Shi
Porous activated carbons (PACs) are promising candidates to capture CO2 through physical adsorption because of their chemical stability, easy-synthesis, cost-effectiveness and good recyclability. However, their low CO2 adsorption capacity, especially low CO2/N2 selectivity, has limited their practical applications. In this work, an optimized PAC with a large specific surface area, a small micropore size, and a large micropore volume has been synthesized by one-step carbonization/activation of casein using K2CO3 as a mild activation agent. It showed a remarkably enhanced CO2 adsorption capacity as high as 5.78 mmol g−1 and an excellent CO2/N2 selectivity of 144 (25 °C, 1 bar). Based on DFT calculations and experimental results, the coexistence of adjacent pyridinic N and –OH/–NH2 species was proposed for the first time to make an important contribution to the ultra-high CO2 adsorption performance, especially CO2/N2 selectivity. This work provides effective guidance to design PAC adsorbents with high CO2 adsorption performance. The content of pyridine N combined with –OH/–NH2 was further elevated by additional nitrogen introduction, resulting in a further enhanced CO2 adsorption capacity up to 5.96 mmol g−1 (25 °C, 1 bar). All these results suggest that, in addition to the well-defined pore structure, pyridinic N with neighboring OH or NH2 species played an important role in enhancing the CO2 adsorption performance of PACs, thus providing effective guidance for the rational design of CO2 adsorbents.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Nano Materials
·
2022
·
IF 6.14
Han Li,Shanshan Lv,Yan Zhou,Qikang Wu,Shaohuan Liu,Taiyu Chen,Wanying Li,Zheng Chen
Through the pyrolysis of melamine–formaldehyde resin (MF) at different temperatures, the obtained mesoporous nitrogen-doped graphitized carbon (MNC) materials are detected to have different compositions of nitrogen species. With the increase in the pyrolysis temperature, the nitrogen contents decreased significantly, especially the proportion of pyridinic N and pyrrolic N species. The graphitic N dominated in NNC-1000 °C (MNC-10) with extremely low defects and a highly graphitized degree. MNC-10 could realize selective oxidation of cyclohexene with 90.1% conversion and 92.0% selectivity on the allylic α-position and can be recycled five times without obvious decline in activity and selectivity. Although MNC obtained at 900 °C (MNC-9) has comparable activity to MNC-10, the recycle experiments of MNC-9 show a considerable decline in conversion. The obvious leaching of nitrogen contents, especially the pyridinic N species in MNC-9, resulted in more defects, which are unfavorable to catalysis. The N species in the carbon layer play a positive role in the delocalized electrons promoting cyclohexene activation and tert-butyl hydroperoxide decomposition. Thereby, peroxyl radicals are formed and trigger the subsequent propagation of the radical reaction.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）