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carbon doping

Alexey S Galushko, Evgeniy G Gordeev, Valentine P Ananikov
A thermally induced cascade process leading to the formation of stable micro- and nanometer-size phosphoric droplets was developed starting from a molecular precursor. Microwave-induced pyrolysis of 1,2,3,4,5-pentaphenylphosphole oxide proceeded through a series of subsequent transformations involving formation of phosphorus-doped graphene oxide layers, seeding of carbon surface with phosphorus centers, and assembling of stable droplets. A complex nanostructured organization of the material was established in a remarkably short time of 3 min, and the process was performed in a thermally induced manner using microwave irradiation...
December 14, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Chunyu Cui, Jiantie Xu, Yiqiong Zhang, Zengxi Wei, Minglei Mao, Xin Lian, Shuangyin Wang, Chongyin Yang, Xiulin Fan, Jianmin Ma, Chunsheng Wang
Antimony (Sb) based materials have been considered as one of promising anodes for sodium ion batteries (SIBs) owing to their high theoretical capacities and appropriate sodium inserting potentials. So far, the reported energy density and cycling stability of the Sb based anodes for SIBs are quite limited and need to be significantly improved. Here, we develop a novel Sb/C hybrid encapsulating the Sb nanorods into highly conductive N & S co-doped carbon (Sb@(N, S-C)) frameworks. As an anode for SIBs, the Sb@(N, S-C) hybrid maintains high reversible capacities of 621...
December 14, 2018: Nano Letters
Jian Xie, Jianglin Ye, Fei Pan, Xuemei Sun, Kun Ni, Hong Yuan, Xiangyang Wang, Na Shu, Chunhua Chen, Yanwu Zhu
Although with an extremely high theoretical capacity (3860 mA h g-1 ), the lithium (Li) metal anodes reported so far typically possess capacities of ≤5 mA h cm-2 and cyclable at currents of ≤5 mA cm-2 . In this work, a hierarchal carbon scaffold is designed with the self-growth of carbon nanotubes (CNTs) in nickel-decorated melamine sponges via thermal annealing. It is found that the nitrogen-doped carbon obtained from the melamine sponge, coupled with CNTs, provides an overall strong yet internally flexible host which enables an areal capacity of up to 15 mA h cm-2 cyclable at a charging/discharging current of 15 mA cm-2 as Li metal anodes...
December 14, 2018: Advanced Materials
Tim Sobolevsky, Brian Ahrens
Both AICAR and mannitol are prohibited for use in sports, but no decisive criteria that would guide anti-doping laboratories on data interpretation have been established so far. In an attempt to help harmonize reporting and management of analytical findings, reference population data collected for the US athletes are presented. Upon analysis of 12377 samples, mean urinary AICAR concentration was found to be 647 ± 365 ng/mL with median value of 574 ng/mL, 99th percentile at 1786 ng/mL and 99.7th percentile at 2151 ng/mL...
December 12, 2018: Drug Testing and Analysis
Lili Han, Xijun Liu, Jinping Chen, Ruoqian Lin, Haoxuan Liu, Fang Lu, Seongmin Bak, Zhixiu Liang, Shunzheng Zhao, Eli Stavitski, Jun Luo, Radoslav R Adzic, Huolin Xin
NH3 synthesis by electrocatalytic N2 reduction reaction (NRR) under ambient conditions is an appealing alternative to the industrial method that requires high temperature and pressure. Herein, we report single Mo atoms anchored to N-doped porous carbon, which works as a cost-effective catalyst for NRR. Benefiting from the optimally high density of active sites and hierarchically porous carbon frameworks, this catalyst achieves a high NH3 yield rate (34.0 ± 3.6 μgNH3 h-1 mgcat.-1) and a high Faradaic efficiency (14...
December 12, 2018: Angewandte Chemie
Jieting Ding, Shan Ji, Hui Wang, Dan J L Brett, Bruno G Pollet, Rongfang Wang
The development of alternative electrocatalysts exhibiting high oxygen reduction reaction (ORR) activity is vital for the deployment of large-scale clean energy devices, such as fuel cells and Zn-air batteries. N-doped carbon materials offer a promising platform for the design and synthesis of electrocatalysts due to their high ORR activity, high surface area and tuneable porosity. In this study, MnO nanoparticles entrapped N-doped mesoporous carbon compounds (MnO/NC) were developed as electrocatalysts for ORR, and their performances were evaluated in operational zinc-air batteries...
December 12, 2018: Chemistry: a European Journal
Dongna Liu, Xiaoming Xu, Jian Tan, Jiexin Zhu, Qi Li, Yanzhu Luo, Peijie Wu, Xiao Zhang, Chunhua Han, Liqiang Mai
High-capacity anodes of lithium-ion batteries generally suffer from poor electrical conductivity, large volume variation, and low tap density caused by prepared nanostructures, which make it an obstacle to achieve both high-areal capacity and stable cycling performance for practical applications. Herein, micrometer-sized porous Fe2 N/C bulk is prepared to tackle the aforementioned issues, and thus realize both high-areal capacity and stable cycling performance at high mass loading. The porous structure in Fe2 N/C bulk is beneficial to alleviate the volumetric change...
December 7, 2018: Small
Feng Liang, Degang Zhao, Desheng Jiang, Zongshun Liu, Jianjun Zhu, Ping Chen, Jing Yang, Shuangtao Liu, Yao Xing, Liqun Zhang
Both yellow luminescence (YL) and blue luminescence (BL) bands of GaN films have been investigated for decades, but few works report the relationship between them. In this study, two sets of GaN samples grown via metalorganic chemical vapor deposition (MOCVD) were investigated. A close relationship was found between the YL and BL bands for unintentionally doped GaN and Si-doped GaN samples, both of which were grown without intentional acceptor doping. It was found that the intensity ratio of blue luminescence to yellow luminescence ( IBL / IYL ) decreases sharply with the increase in carbon impurity concentration, even though both IBL and IYL increase obviously...
December 10, 2018: Nanomaterials
Aochen Wang, Ming Hu, Liwei Zhou, Xiaoyong Qiang
Self-powered operation, flexibility, excellent mechanical properties, and ultra-high sensitivity are highly desired properties for pressure sensors in human health monitoring and anthropomorphic robotic systems. Piezoelectric pressure sensors, with enhanced electromechanical performance to effectively distinguish multiple mechanical stimuli (including pressing, stretching, bending, and twisting), have attracted interest to precisely acquire the weak signals of the human body. In this work, we prepared a poly(vinylidene fluoride-trifluoroethylene)/ multi-walled carbon nanotube (P(VDF-TrFE)/MWCNT) composite by an electrospinning process and stretched it to achieve alignment of the polymer chains...
December 7, 2018: Nanomaterials
Dae Kyom Kim, Sehwa Bong, Xuanzhen Jin, Kwang-Dong Seong, Minsik Hwang, Nam Dong Kim, Nam-Ho You, Yuanzhe Piao
Efficient strategies to prepare carbon materials with improved electrochemical performance for supercapacitor have been in great demand. Herein, we develop multiple-heteroatom-doped carbons (from single- to triple-doped) by pyrolysis of polyimide precursors using a facile in situ approach. This approach can be used to tune heteroatom compositions by controlling the desired polyimide monomer functional groups as well as introducing external doping sources into the polyimide precursor solutions. Various types of multiple-heteroatom-doped carbons such as N; N,S-; N,F-; N,S,B-; and N,F,B-doped carbon are synthesized...
December 13, 2018: ACS Applied Materials & Interfaces
Basudev Sahoo, Carsten Kreyenschulte, Giovanni Agostini, Henrik Lund, Stephan Bachmann, Michelangelo Scalone, Kathrin Junge, Matthias Beller
By applying N-doped carbon modified iron-based catalysts, the controlled hydrogenation of N-heteroarenes, especially (iso)quinolones, is achieved. Crucial for activity is the catalyst preparation by pyrolysis of a carbon-impregnated composite, obtained from iron(ii) acetate and N -aryliminopyridines. As demonstrated by TEM, XRD, XPS and Raman spectroscopy, the synthesized material is composed of Fe(0), Fe3 C and FeN x in a N-doped carbon matrix. The decent catalytic activity of this robust and easily recyclable Fe-material allowed for the selective hydrogenation of various (iso)quinoline derivatives, even in the presence of reducible functional groups, such as nitriles, halogens, esters and amides...
November 14, 2018: Chemical Science
Georgios Giannakakis, Maria Flytzani-Stephanopoulos, E Charles H Sykes
Heterogeneous catalysts are workhorses in the industrial production of most commodity and specialty chemicals, and have widespread energy and environmental applications, with the annual market value of the catalysts themselves reaching almost $20 billion in 2018. These catalysts are complex, comprising multicomponent materials and multiple structures, making their rational design challenging, if not impossible. Furthermore, typical active metals like Pt, Pd, and Rh are expensive and can be susceptible to poisoning by CO, coking, and they are not always 100% selective...
December 12, 2018: Accounts of Chemical Research
Shan Chen, Yong Zheng, Bing Zhang, Yiyu Feng, Jixin Zhu, Jingsan Xu, Chao Zhang, Wei Feng, Tianxi Liu
The breakthrough of non-precious metal catalysts replacing platinum-based catalysts towards the oxygen reduction reaction (ORR) is extremely urgent for the development of high-efficiency energy conversation systems. Herein, a solution-processed condensation polymerization using cyanuric chloride and piperazine as the monomers was proposed for synthesis of a nitrogen-rich covalent organic polymer (COP). High contents of precisely tailored pyridinic-N within the COP facilitate the formation of the Co-N coordination between Co ions and N species...
December 12, 2018: ACS Applied Materials & Interfaces
Chunmei Li, Siyu Yu, Xiaoxu Zhang, Yun Wang, Chunbo Liu, Gang Chen, Hongjun Dong
It is still a challenging work to realize the universality of photocatalytic materials for unselective removing various organic pollutants in water. Here a surface dual-doped Cu/Cl-g-C3 N4 photocatalyst is firstly prepared, which exhibits much more superior photocatalytic performance for degrading multifarious persistent organic pollutants including tetracycline hydrochloride (TC-HCl), o-chlorophenol, bisphenol A and 2-mercaptobenzothiazole in water than pure g-C3 N4 . The high-efficiency and unselective photocatalytic degradation performance derives from the surface dual-doped effect of Cu/Cl elements on g-C3 N4 , which results in the extended visible light harvest range, elevated CB potential and improved the separation efficiency of charge carriers...
December 3, 2018: Journal of Colloid and Interface Science
Yingping Li, Yong Jia, Qi Zeng, Xiaohui Jiang, Zhengjun Cheng
We used thiamine nitrate (TN) as single material to fabricate nitrogen and sulfur co-doped carbon quantum dots (N,S-CQDs) with a quantum yield of 10.4% through one-pot hydrothermal method, and its properties were characterized by TEM, XPS, FTIR, fluorescence (FL) and UV-vis spectrophotometer, respectively. The fluorescence of N,S-CQDs was effectively quenched in the presence of vitamin B12 (VB12)/tartrazine due to Förster resonance energy transfer (FRET). Moreover, the rate (KT ) and efficiency (E%) of energy transfer from N,S-CQDs (as a donor) to VB12/tartrazine (as an acceptor) enhanced with increasing the concentrations of acceptor, and the KT and E% were also varied with the change of excitation wavelengths (from 338 to 408 nm)...
December 4, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Jing Li, Dandan Wu, James Iocozzia, Haiwei Du, Xueqin Liu, Yupeng Yuan, Wei Zhou, Zhen Li, Zhaoming Xue, Zhiqun Lin
The past decade has witnessed rapid advances in graphitic carbon nitride (g-C3N4) as it is metal-free and affords highly stable hydrogen (H2) generation. Notably, density functional theory calculations show that C-substitution for N in g-C3N4 can increase Π-electron availability and in turn significantly increase the photocatalytic H2 generation. However, creating such C-incorporated g-C3N4 has proven challenging owing to the higher electronegativity of N over C. Here, we report a rapid and highly efficient strategy for introducing C into g-C3N4 by copolymerizing Π-electrons-rich barbituric acid with melamine via a facile microwave-assisted heating, thereby eliminating the issues in conventional electric furnace heating, such as the severe volatilization, due to the mismatch on the sublimation temperatures of barbituric acid and melamine...
December 7, 2018: Angewandte Chemie
Dekun Wu, Qing Xu, Jing Qian, Xiaopeng Li, Yuhan Sun
Covalent organic frameworks (COFs) are a new class of crystalline porous polymers, which comprise mainly of carbons and are versatile for integrating heteroatoms such as B, O and N to the skeletons. The designable structure and abundant composition render COFs useful as precursors for heteroatom-doped porous carbons for energy storage and conversion. Herein, we describe a multifunctional electrochemical catalyst by pyrolysis of a bimetallic COF. The catalyst possesses hierarchical pores and abundant iron and cobalt nanoparticles embedded with standing carbon layers...
December 11, 2018: Chemistry: a European Journal
Yuhang Li, Zhiwei Qiao, Yonghai Cao, Hongjuan Wang, Hong Liang, Hao Yu, Feng Peng
The superoxide decay behavior is evaluated by contrastive potential energy surface analyses from theoretical calculations. The presence of carbon surface enhances the superoxide decay via disproportionation instead of electroreduction, which is a non-electrochemical reaction impeding the increase in energy efficiency for relevant energy conversion applications. Nitrogen doping in carbon effectively retards the disproportionation by influencing the oxygen stretching vibration and changing the proton coupled electron transfer trend...
December 11, 2018: ChemSusChem
Xinyang Li, Yiqiang Sun, Tao Zhang, Yu Bai, Xianjun Lyu, Weiping Cai, Yue Li
Indoor formaldehyde removal is of great significance to reduce public health risk. Herein, we report a facile method for preparing N-doped nanoporous carbon through direct carbonization of MOFs (ZIF-8) to remove harmful formaldehyde (HCHO). The prepared N-doped nanoporous carbon exhibited uniform morphology and large specific surface area. Moreover, the forms of N-functional groups on the N-doped nanoporous carbon had a dominant effect on its formaldehyde adsorption activity. As a result, HCHO adsorption capacity of the optimized N-doped nanoporous carbon was ca...
December 10, 2018: Nanotechnology
Jiangnan Huang, Yonghai Cao, Hejie Wen, Ju Zhang, Hongjuan Wang, Hao Yu, Feng Peng
Heteroatom doping endows magnetic carbons with unique electronic features and rich surface chemistry, significantly enhancing their adsorption performances for the environmental remediation. In this work, fluorine and nitrogen co-doped magnetic nanocarbon fibers (FN-MCFs) were prepared via a facile carbonization method combined with electrospinning procedure. FN-MCFs were used as adsorbents for Cr(VI) removal, displaying a remarkable activity with as high as 153.61 mg/g and 0.58 mg/m2 of the Cr(VI) removal ability...
December 3, 2018: Journal of Colloid and Interface Science
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