RSC Advances
·
2015
·Vol. 5
·期 35
·27953-27963
·
IF 3.84
Stavroula Sfaelou,Xiaodong Zhuang,Xinliang Feng,Panagiotis Lianos
Sulfur-doped porous carbon nanosheets have been prepared by pyrolysis of graphene-coupled conjugated microporous polymers under an inert atmosphere. The obtained carbon nanosheets exhibited large specific surface areas up to 642 m2 g−1 and high sulfur weight content up to 7.11%. These highly porous carbon nanosheets have been studied as metal-free oxygen reduction electrocatalysts in alkaline environments and they were found to undergo oxygen reduction via a major 4-electron transfer pathway. They were then examined as substitutes for Pt–carbon electrocatalysts in PhotoFuelCells functioning in the presence of ethanol as a model fuel. It has been shown that sulfur doped porous carbon nanosheets yield functional cells with approximately the same characteristics as those employing Pt–carbon electrocatalysts, therefore, they mark a new class of metal-free catalysts.
研究领域:
材料科学
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电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2021
·
IF 8.128
Lixia Wang,Rongfei Ye,Panming Jian,Jiangyong Liu
Metal-free catalysts with environmental friendless, cost-competitiveness and less susceptibility to leaching and poisoning over metal-based catalysts, have revolutionized in the catalysis domain. In this respect, we herein report the first application of cheap and abundant pumpkin-derived N -doped porous carbon for the reduction of 2-methyl-4-nitrophenol assisted by NaBH 4 . The obtained catalyst is cost-competitive, efficient and robust, with an attractive mass-normalized rate constant of 4.73 s −1 g −1 and good recycling performance. Systematical analyses demonstrate that the 2-methyl-4-nitrophenol reduction reaction catalyzed by the N -doped carbon proceeds through the Langmuir–Hinshelwood kinetics and the performance enhancement benefits from the strong adsorption and activation of the substrates induced by the electronic modulation in the carbon framework via N -doping. This study opens up new avenues for the high-value use of pumpkin as well as the development of metal-free strategy in more catalytic applications.
研究领域:
催化化学
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环境科学
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材料科学
✓ 已验证
DOI
高影响因子
GREEN CHEMISTRY
·
2025
·
IF 9.2
Siwei Xu,Nian Xiang,Jie He,Yang Li,Huankun Nie,Liang Huang,Chongbei Wu,Zehui Zhang
Developing new catalytic methods in the effective syntheses of 2,5-furandicarboxylic acid (FDCA) and glycolic acid (GA) through the selective oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) and 1,3-dihydroxyacetone (DHA) offer green and sustainable alternative routes to fossil-based routes in polymer chemistry. Current methods are based on the metal catalysts. Herein, a metal-free carbon catalyst was discovered to be robust for synthesis of FDCA and GA through the selective oxidation of HMF and DHA, respectively. Experimental data and theoretical calculations indicate defective carbon sites and surface oxygen-containing functional groups play pivotal roles in the excellent catalytic performance. The defective sites activate oxygen molecules, producing reactive oxygen species, while the oxygen-functional groups enhance the adsorption and activation of substrates on the catalyst surface, thereby boosting catalytic efficiency. Additionally, the plausible reaction mechanisms were proposed for the selective oxidation of HMF to FDCA as well as DHA to GA over the carbon catalyst are presented.
研究领域:
化学工程
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催化科学
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材料科学
✓ 已验证
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 4
·2718-2725
·
IF 3.201
Fan Yang,Yan Cao,Zhuo Chen,Xing He,Liqiang Hou,Yongfeng Li
Boron and nitrogen co-doped graphene-like carbon (BNG) is a metal-free catalyst that has been synthesized by combining ball-milling with thermal treatment. Firstly, the edge-selectively-functionalized graphene nanoplatelets (EFGnPs) were prepared by ball milling of the pristine graphite, which can facilitate boron incorporation. BNG catalysts with a high content of boron and nitrogen can then be obtained by pyrolysis of a mixture of EFGnPs and boric acid. We found that the reduction of nitroarenes can be catalyzed using a low BNG loading and a small amount of N2H4 in ethanol to form aminoarenes in high yields. The type of boron species in the BNG catalyst has an important effect on the reduction reaction. Furthermore, the catalyst containing the most B/N shows the highest catalytic activity during the reduction of nitroarenes, indicating that the doped B/N within the BNG is a key active site in impelling this reaction. Moreover, the BNG catalyst can be used six times, and no dehalogenation phenomenon occurs during the reduction process for halogen-substituted nitroarenes in contrast to the case when conventional metal catalysts are used.
研究领域:
材料科学
·
有机化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Energy Materials
·
2021
·
IF 6.024
Yifan Liu,Rashad Ali,Jun Ma,Wei Jiao,Liangjun Yin,Chunhong Mu,Xian Jian
The hydrogen evolution reaction (HER) is an emerging renewable energy source to derive clean, efficient, and high-energy-density hydrogen fuel from electrochemical water splitting mostly by using traditional noble-metal-based catalysts. However, their scarcity has led to the emergence of carbon-based materials which are exceptionally promising alternatives for the HER. Herein, graphene capsules-decorated boron–carbon–nitride sheets are developed by pyrolyzing a mixture of pyridine borane and custom-made GCs. The 3D hollow GCs effectively increase the surface area to supplement more exposed active sites for the hydrogen adsorption/desorption reaction. The carbon-rich ternary hybrid structure favors adjusting the electrical conductivity, which provides better HER catalytic performances (overpotential of 333 mV at 10 mA cm–2) in acidic conditions. The long-term stability for 24 h and the simplest designing technique propose an effective metal-free electrocatalyst for commercial applications in the renewable energy field.
研究领域:
材料科学
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能源科学
✓ 已验证
DOI
高影响因子
NANOTECHNOLOGY
·
2016
·Vol. 27
·期 40
·405401
·
IF 3.573
Hao Wang,Kai Chen,Yingjie Cao,Juntong Zhu,Yining Jiang,Lai Feng,Xiao Dai,Guifu Zou
A facile, self-foaming strategy is reported to synthesize porous, nitrogen-doped carbon nanosheets (N-CNSs) as a metal-free electrocatalyst for oxygen reduction reaction (ORR). Benefiting from the synergistic functions of N-induced active sites, a highly specific surface area and continuous structure, the optimal N-CNS catalyst exhibits Pt-like ORR activity (positive onset potential of ∼0 V versus Ag/AgCl and limiting current density of 5 mA cm−2) through a four-electron transfer process in alkaline media with excellent cycle stability and methanol tolerance. This work not only provides a promising metal-free ORR catalyst but also opens up a new path for designing carbon-based materials towards broad applications.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Qian Yu,Jingshu Wang,Haibo Li,Ruiqing Li,Suyuan Zeng,Rui Li,Qingxia Yao,Hongyan Chen,Konggang Qu,Yao Zheng
In the electrocatalytic oxygen reduction and hydrogen evolution reactions (ORR/HER), metal-free carbon-based materials presented great potentials as alternatives to Pt because of their flexible adjustability of electronic and geometric properties. The pursuit of high-performance carbons demand for high-level doping, large surface area and high graphitization, but the improvement of the former two aspects would inevitably impair the third one, which seems a contradictive proposition. Herein, by a facile “mix-and-pyrolyze” method, natural DNA was first developed to synthesize N, P, S-tridoped carbons (NPSC) with porous sheet structures, high graphitization, large surface areas and abundant high-quality dopants simultaneously. Thus, the newly-prepared NPSC displays superior alkaline ORR performance comparable to Pt/C together with excellent acidic activity and better stability. Meanwhile, NPSC is one of most active acidic HER catalysts and the best alkaline HER catalyst among carbon counterparts. Density function theory computation reveled the origins of superior performance are attributed to positively charged C sites neighboring to S for ORR and P sites for HER because of DNA-derived advantaged structural features. The as-fabricated rechargeable zinc–air battery based on current tridoped carbon has closed peak power density and specific capacity but much better charge–discharge stability compared with Pt/C.
研究领域:
材料科学
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电化学
·
计算化学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2022
·
IF 9.136
Xiangyang Tian,Haoxin Huang,Huiping Zhang,Ying Yan
Four different types of structured nitrogen-doped carbon nanotube membranes (C50, NC25, NC50, N25C25) were used as metal-free catalysts for phenol degradation. Firstly, nitrogen-doped carbon nanotubes were prepared on paper-like sintered stainless steel fibers (PSSF) by chemical vapor deposition using melamine and acetylene as dual precursors, then the nitric acid was used to remove amorphous carbon and catalyst particles in the tubes. Subsequently, TEM, XPS, N 2 adsorption and desorption and other characterization techniques were used to investigate the structure and morphology of the catalysts. Characterization results showed that the use of dual precursor could well adjust the nitrogen content in carbon nanotubes, and nitrogen doping could change the hollow structure of carbon nanotubes into rough bamboo-like and corrugated structure. Meanwhile, acid treatment significantly increased the specific surface area, among which the value of HN25C25 reached 38.15 m 2 /g. Pristine and acid-treated catalysts were then used to activate peroxymonosulfonate (PMS) in a structured fixed bed reactor. NC25 and N25C25 were able to mineralize 46% and 17.5% of phenol at 1 h, but the TOC conversion rate only maintained at about 10% in the subsequent reaction time. After acid treatment, HNC25 and HN25C25 were able to mineralize up to 76% and 84% of phenol, and the TOC conversion rate maintained at about 70% within 7 h. the high leaching of Fe in the acid-treated catalysts could be attributed to the formation of small carboxylic acids and the destruction of the PSSF support during the reaction. At last, radical inhibition experiments and ESR spectra showed that sulfate radicals and hydroxyl radicals were the main active species in the reaction. The increase in the proportion of active nitrogen species and the improvement in contact efficiency could explain the higher mineralization efficiency of phenol catalyst after acid treatment.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2025
·
IF 4.9
Weitao Wang,Shuang Yue,Huan Wang,Jiaqi Zhu,Zhen-Hong He,Zhao-Tie Liu
Selective oxidation of lignin-derived vanillyl alcohol to vanillin is a vital reaction due to the widely application of vanillin. From aspect of green catalysis and sustainability, metal-free based heterogeneous catalyst for the entitled reaction is promising. In the present work, Se doped boron carbonitride (Se-BCN) nanotubes catalyst was rationally prepared and employed as the metal-free catalyst for the entitled reaction. The conversion can achieve 94.4 % with the selectivity of 89.4 % at 120 °C for 4 h, which is higher than most reported metal-based catalytic system. The reasons for the enhanced activity and selectivity of Se doped BCN nanotubes catalyst were revealed from the kinetic investigation and adsorption of vanillyl alcohol and vanillin. Mechanism study reveals that radicals are involved in the entitled reaction.
研究领域:
化学催化
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2018
·
IF 4.908
Xiaoyu Tian,Minghua Zhou,Ming Li,Chaolin Tan,Liang Liang,Pei Su
To increase the performance of MFCs, nitrogen-doped activated carbon (AC) for rolling-pressed air-cathode was synthesized using inexpensive melamine as nitrogen source by pyrolysis. The ratio of melamine to activated carbon (N/C) and pyrolysis temperature were optimized to be 10 and 900 °C. To clarify how the structure and active nitrogen content in different preparations influence the ORR performance, series of characterizations were carried out, and a good agreement between the content of pyridinic type N and high ORR activity was observed. As a dominant four electron cathode catalyst, AC-N10-900 exhibited the best performance both in electrochemical and MFCs tests in comparison with AC and Pt/C. The maximum power density was 1042 mW m −2 , which was 65.4% and 116.2% higher than that of AC and Pt/C. Therefore, AC-N10-900, one of cost-effective and metal-free MFCs cathode catalysts towards ORR, is expected to alternate precious metal for high performance in MFCs.
研究领域:
环境科学
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材料科学
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2014
·
IF 5.211
Ce Han,Xiangjie Bo,Yufan Zhang,Mian Li,Liping Guo
Nitrogen and sulfur co-doped onion-like mesoporous carbon vesicle (NS-MCV) with multilayer lamellar structure is synthesized as a metal-free catalyst through a convenient and economical procedure. The synthesized materials are systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra , nitrogen adsorption–desorption, and X-ray photoelectron spectroscopy (XPS). The characterization results demonstrate that N and S atoms can be successfully doped into the framework of MCV with little impact on the morphology and structure. The NS-MCV manifests a remarkably high electrocatalytic activity as a metal-free electrocatalyst for the oxygen reduction reaction (ORR) with mainly a four-electron transfer pathway. Moreover, in contrast to the commercially available Pt/C catalyst, the NS-MCV shows much better long-term stability and tolerance toward methanol crossover in an alkaline medium . Such excellent performances can be mainly attributed to the synergistic effect arising from the addition of N and S heteroatom , optimized S content and high surface area. The NS-MCV with a simple synthesis method may further exploited as potentially efficient and inexpensive metal-free ORR catalyst materials.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Xinpeng Guo,Jian Yin,Haishuai Cui,Jiating Gong,Siqi Cheng,Yunlong Li,Xinglu Deng,Feiying Tang,Shaofeng Xiong,Pingle Liu
The N-formylation reaction of amines by CO 2 hydrogenation is a promising method for converting CO 2 into chemical products with industrial application value. However, most of the currently developed catalysts are metal-homogeneous catalysts, which contain metal pollution and are not easy to recycle. Thus, we modified carbon nanotubes with N-containing amino compounds and prepared a polyethylenimine (PEI) grafted carbon nanotubes metal-free catalyst, which was applied to the N-formylation reaction of CO 2 and aniline. By adjusting the grafting concentration and the type of amino compound, the acid-base properties and surface defects of the catalyst were regulated. The CNT-0.5PEI catalyst had the optimal catalytic activity after 12 h of reaction at 80 °C, with a conversion rate of 95.41 % for aniline and a selectivity of 94.04 % for the target product N-formylaniline. It reveals that its catalytic performance can be comparable to the reported homogeneous catalysts. Our research found that increasing the surface defects and basic sites of carbon nanotubes was conducive to the enrichment and activation of CO 2 , thereby enhancing the catalytic activity. The experimental and calculation results indicate that the reaction has relatively low activation energy under the catalysis of CNT-0.5PEI, and the catalyst has the strongest adsorption capacity for CO 2 and aniline reactants. In addition, the CNT-0.5PEI displays a wide range of substrate applicability and excellent cyclic stability. Therefore, cheap and environmentally friendly metal-free modified carbon nanotube catalyst is an ideal substitute for scarce and polluting metal homogeneous materials. It has important reference significance for the efficient conversion and utilization of CO 2 catalyzed by metal-free catalyst.
研究领域:
化学工程
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
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