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https://read.qxmd.com/read/30878849/n-doped-carbon-dots-under-xenon-lamp-irradiation-fluorescence-red-shift-and-its-potential-mechanism
#1
Hongwei Hu, Xinmeng Tian, Yixuan Gong, Guolan Ren, Jiangong Liang
Despite extensive research on carbon dots (CDs), rare studies have been performed on the photostability of CDs. Here, the photostability of CDs synthesized with 3-aminobenzoic acid were systematically investigated under different pH conditions (5.0, 7.4 and 9.0). The results showed that under Xenon lamp irradiation, the fluorescence (FL) intensity of the CDs exhibited an increase first and then a decrease, with a gradual shift of the maximum emission wavelength to longer wavelength. Further investigation indicated that the irradiation induced the change of the CD surface functional groups and gave rise to aggregation, resulting in the formation of larger particles...
March 10, 2019: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://read.qxmd.com/read/30876631/captavidin-as-a-regenerable-biorecognition-element-on-boron-doped-diamond-for-biotin-sensing
#2
Alyah Buzid, Phyllis E Hayes, Jeremy D Glennon, John H T Luong
Captavidin, a nitrated avidin with moderate affinity with biotin, irreversibly adsorbs on carboxymethylcellulose to form a regenerable biorecognition element for biotin. This layer was retained and stabilized on a boron-doped diamond electrode by a Nafion film for repeated impedance analyses of biotin down to below 1 nM. The labeless electrochemical sensing scheme was then demonstrated for the analysis of biotin in blood plasma. The incorporation of captavidin confers detection specificity and regenerability, whereas the Nafion and carboxymethylcellulose layers circumvent the diffusion of endogenous electroactive species...
June 20, 2019: Analytica Chimica Acta
https://read.qxmd.com/read/30876592/highly-fluorescent-nitrogen-doped-carbon-dots-for-the-determination-and-the-differentiation-of-the-rare-earth-element-ions
#3
Shengnan Wang, Shuai Liu, Jianyu Zhang, Yan Cao
As indispensable and strategic elements, Rare Earth Elements (REEs) have been found wide high-tech applications in many modern industries. Their mining, extraction and purification address on economic and environmental significances. This study was the first to report the successful determination and differentiation of rare earth metals using the Nitrogen-doped Carbon Dots (NCDs). NCDs were synthesized via the one-step hydrothermal treatment method starting from folic acid. The as-received NCDs can emit bright blue fluorescence at 440 nm in a high quantum yield of 85% due to the fluorescence enhancement effect of N dopant atoms on NCDs' surface...
June 1, 2019: Talanta
https://read.qxmd.com/read/30873660/identifying-the-activation-of-bimetallic-sites-in-nico-2-s-4-g-c-3-n-4-cnt-hybrid-electrocatalysts-for-synergistic-oxygen-reduction-and-evolution
#4
Xiaopeng Han, Wei Zhang, Xiaoya Ma, Cheng Zhong, Naiqin Zhao, Wenbin Hu, Yida Deng
Hybrid materials composed of transition-metal compounds and nitrogen-doped carbonaceous supports are promising electrocatalysts for various electrochemical energy conversion devices, whose activity enhancements can be attributed to the synergistic effect between metallic sites and N dopants. While the functionality of single-metal catalysts is relatively well-understood, the mechanism and synergy of bimetallic systems are less explored. Herein, the design and fabrication of an integrated flexible electrode based on NiCo2 S4 /graphitic carbon nitride/carbon nanotube (NiCo2 S4 @g-C3 N4 -CNT) are reported...
March 15, 2019: Advanced Materials
https://read.qxmd.com/read/30872576/tuning-orbital-orientation-endows-molybdenum-disulfide-with-exceptional-alkaline-hydrogen-evolution-capability
#5
Yipeng Zang, Shuwen Niu, Yishang Wu, Xusheng Zheng, Jinyan Cai, Jian Ye, Yufang Xie, Yun Liu, Jianbin Zhou, Junfa Zhu, Xiaojing Liu, Gongming Wang, Yitai Qian
Molybdenum disulfide is naturally inert for alkaline hydrogen evolution catalysis, due to its unfavorable water adsorption and dissociation feature originated from the unsuitable orbital orientation. Herein, we successfully endow molybdenum disulfide with exceptional alkaline hydrogen evolution capability by carbon-induced orbital modulation. The prepared carbon doped molybdenum disulfide displays an unprecedented overpotential of 45 mV at 10 mA cm-2 , which is substantially lower than 228 mV of the molybdenum disulfide and also represents the best alkaline hydrogen evolution catalytic activity among the ever-reported molybdenum disulfide catalysts...
March 14, 2019: Nature Communications
https://read.qxmd.com/read/30871112/controlling-nitrogen-doping-in-graphene-with-atomic-precision-synthesis-and-characterization
#6
REVIEW
Tomotaroh Granzier-Nakajima, Kazunori Fujisawa, Vivek Anil, Mauricio Terrones, Yin-Ting Yeh
Graphene provides a unique platform for the detailed study of its dopants at the atomic level. Previously, doped materials including Si, and 0D-1D carbon nanomaterials presented difficulties in the characterization of their dopants due to gradients in their dopant concentration and agglomeration of the material itself. Graphene's two-dimensional nature allows for the detailed characterization of these dopants via spectroscopic and atomic resolution imaging techniques. Nitrogen doping of graphene has been well studied, providing insights into the dopant bonding structure, dopant-dopant interaction, and spatial segregation within a single crystal...
March 12, 2019: Nanomaterials
https://read.qxmd.com/read/30870784/zno-nanoparticles-encapsulated-in-nitrogen-doped-carbon-material-and-silicalite-1-composites-for-efficient-propane-dehydrogenation
#7
Dan Zhao, Yuming Li, Shanlei Han, Yaoyuan Zhang, Guiyuan Jiang, Yajun Wang, Ke Guo, Zhen Zhao, Chunming Xu, Ranjia Li, Changchun Yu, Jian Zhang, Binghui Ge, Evgenii V Kondratenko
Non-oxidative propane dehydrogenation (PDH) is an attractive reaction from both an industrial and a scientific viewpoint because it allows direct large-scale production of propene and fundamental analysis of C-H activation respectively. The main challenges are related to achieving high activity, selectivity, and on-stream stability of environment-friendly and cost-efficient catalysts without non-noble metals. Here, we describe an approach for the preparation of supported ultrasmall ZnO nanoparticles (2-4 nm, ZnO NPs) for high-temperature applications...
February 23, 2019: IScience
https://read.qxmd.com/read/30870782/hollow-n-doped-carbon-polyhedrons-with-hierarchically-porous-shell-for-confinement-of-polysulfides-in-lithium-sulfur-batteries
#8
Dong-Hui Yang, Hang-Yu Zhou, Hu Liu, Bao-Hang Han
Herein, hollow N-doped carbon polyhedrons with hierarchical pores were fabricated by etching ZIF-8 crystals and were first used as the host of sulfur for lithium-sulfur batteries. This host possesses both micropores and mesopores, and inner wide cavities, which enable the sulfur to effectively immerse into the polyhedrons without obstacles and simultaneously restrict the escaping of polysulfides by outer carbon shell and abundant N sites. Hence, the polyhedron host combines the physical confinement and chemical interaction for polysulfides by virtue of the unique architecture...
February 27, 2019: IScience
https://read.qxmd.com/read/30869862/a-collaboratively-polar-conductive-interface-for-accelerating-polysulfides-redox-conversion
#9
Bokai Cao, Jiangtao Huang, Yan Mo, Chunyang Xu, Yong Chen, Hai-Tao Fang
In order to alleviate the inferior cycle stability of sulfur cathode, a self-assembled SnO2-doped manganese silicate nanobubbles (SMN) is designed as sulfur/polysulfides host to immobilize the intermediate Li2Sx, and nitrogen-doped carbon (N-C) is coated on SMN (SMN@C). The exquisite N-C conductive network could not only provides sufficient free space for the volume expansion during the phase transition of solid sulfur into lithium sulfide, but also reduces Rct of SMN. During cycling, the soluble polysulfide could be fastened by the silicate with oxygen-rich functional group and hetero nitrogen atoms through chemical bonding, enabling a confined shuttle effect...
March 14, 2019: ACS Applied Materials & Interfaces
https://read.qxmd.com/read/30869708/constituent-tunable-ternary-com-2x-se-2-1-x-m-te-s-sandwich-like-graphitized-carbon-based-composites-as-highly-efficient-electrocatalysts-for-water-splitting
#10
Yu Wang, Li Liu, Yanwei Wang, Ling Fang, Fu Wan, Huijuan Zhang
Herein, we fabricated two groups of component-tunable sandwich-like CoTe2xSe2(1-x) and CoS2ySe2(1-y) graphitized carbon-based composites. Due to the synergistic effect between the sandwich-like structures and anion-doping, CoTe2xSe2(1-x) and CoS2ySe2(1-y) demonstrated attractive catalytic performance towards the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. After optimizing the composition, we found that sandwich-like Co(Te0.33Se0.67)2 possesses optimal OER properties, with a low Tafel slope (44 mV dec-1), a small η10 (272 mV) and eminent stability for 50 h; meanwhile, the Co(S0...
March 14, 2019: Nanoscale
https://read.qxmd.com/read/30869509/insight-into-the-preparation-process-of-fe-doped-na3v2-po4-3-c-from-the-aspects-of-particle-morphology-design-crystal-structure-modulation-and-carbon-graphitization-regulation
#11
Xiaohong Liu, Guilin Feng, Enhui Wang, Hui Chen, Zhen-Guo Wu, Wei Xiang, Yan-Jun Zhong, Yanxiao Chen, Xiao-Dong Guo, Benhe Zhong
The peak-loading shift function of sodium ion batteries in large-grid energy storage station confront great challenge owing to the poor rate performance of cathodes. NASICON type Na3V2(PO4)3 with stable three-dimensional structure and fast ion diffusion channels has been regarded as one of the potential candidates and was widely studied. Nevertheless, a multilevel integrated strategy to boost the performance of Na3V2(PO4)3 from crystal structure modulation, coated carbon graphitization regulation and particle morphology design is rarely reported and deserves much attention...
March 14, 2019: ACS Applied Materials & Interfaces
https://read.qxmd.com/read/30865933/oxygen-reduction-reaction-performance-of-fe-n-c-catalysts-from-ligand-iron-coordinative-supramolecular-precursors
#12
Tong Wu, Yaying Li, Yuntong Li, Jing Hong, Haiyang Wu, Jie Mao, Yuzhe Wu, Qipeng Cai, Conghui Yuan, Lizong Dai
Simultaneous introduction of both transition metal and other inorganic elements into the carbon matrix has attracted great attention in the fabrication of carbon materials with high electrochemical properties. Herein, rational design of ligand-iron coordinative supramolecular precursors is achieved for the fabrication of Fe-N/C catalysts, which possess high oxygen reduction reaction (ORR) performance. A series of precursors are prepared by a simple coordination reaction between a three armed catechol monomer and iron ions...
March 13, 2019: Nanotechnology
https://read.qxmd.com/read/30864582/triangular-graphene-nanofragments-open-shell-character-and-doping
#13
María E Sandoval-Salinas, Abel Carreras, David Casanova
In this work we study the intricacies of the electronic structure properties of triangular graphene nanofragments (TGNFs) in their ground and low-lying excited states by means of ab initio quantum chemistry calculations. We focus our attention on the radical and diradical characters of phenalenyl and triangulene, the smallest members of the TGNF family, and we describe the nature of their low-lying excited states. Moreover, we rationalize the modulation of the electronic and magnetic properties by means of selective boron or nitrogen substitution of carbon sites and by hydrogen saturation...
March 13, 2019: Physical Chemistry Chemical Physics: PCCP
https://read.qxmd.com/read/30861630/mesh-like-carbon-nanosheets-with-high-level-nitrogen-doping-for-high-energy-dual-carbon-lithium-ion-capacitors
#14
Zhao Li, Liujun Cao, Wei Chen, Zechuan Huang, Hao Liu
Li-ion capacitors (LICs) have demonstrated great potential for bridging the gap between lithium-ion batteries and supercapacitors in electrochemical energy storage area. The main challenge for current LICs (contain a battery-type anode as well as a capacitor-type cathode) lies in circumventing the mismatched electrode kinetics and cycle degradation. Herein, a mesh-like nitrogen (N)-doped carbon nanosheets with multiscale pore structure is adopted as both cathode and anode for a dual-carbon type of symmetric LICs to alleviate the above mentioned problems via a facile and green synthesis approach...
March 12, 2019: Small
https://read.qxmd.com/read/30861479/polytetrafluoroethylene-assisted-n-f-co-doped-hierarchically-porous-carbon-as-a-high-performance-electrode-for-supercapacitors
#15
Jiangqi Zhou, Lingrui Xu, Lijie Li, Xin Li
In this study, we propose a novel template and chemical activation method to fabricate the nitrogen and fluorine co-doped hierarchically porous carbon with polytetrafluoroethylene-polyaniline as the precursor and KOH as the activation reagent. The key to this strategy is the utilization of polytetrafluoroethylene as an additive during the process, which not only serves as a fluorine source but also acts as a template to increase the specific surface area. Moreover, polytetrafluoroethylene disappears after carbonization without requiring a complicated template-removal process...
March 6, 2019: Journal of Colloid and Interface Science
https://read.qxmd.com/read/30860616/pt-like-oxygen-reduction-activity-induced-by-cost-effective-mnfeo2-n-carbon
#16
Qixing Zhou, Zhangbin Su, Yidan Tang, Li Ai, Gengtao Fu, Zexing Wu, Dongmei Sun, Yawen Tang
Development of effective and affordable electrocatalysts for the oxygen reduction reaction (ORR) is critical for the renewable-energy technologies. Here we present a novel manganese iron oxide (MnFeO2) as a cost-effective material for the ORR with Pt-like electrochemical properties. Pyrolysis of hybrid agar-hydrogel on NaCl nanocrystals furnishes a unique structure in which the active MnFeO2 particles are uniformly immobilized in the nitrogen-doped porous carbon aerogels (designed as MnFeO2/NPC). Nitrogen-doped carbon is introduced to construct porous mass transfer channels and reduce self-aggregation of MnFeO2 particles...
March 12, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30860536/tailoring-carbon-nitride-properties-and-photoactivity-by-interfacial-engineering-of-hydrogen-bonded-frameworks
#17
Susmita Dolai, Jesús Barrio, Guiming Peng, Andrea Grafmüller, Menny Shalom
The rational synthesis of carbon nitride materials, ranging from polymeric carbon nitride to nitrogen-doped carbon, by supramolecular preorganization of their monomers is a powerful tool for the design of their morphology and photophysical and catalytic activities. Here we show a new facile and scalable approach for the synthesis of ordered CN materials with excellent photoactivity, which consists of supramolecular interfacial preorganization of CN monomers at the interface of two non-miscible solvents. Molecular dynamic simulations supported by experimental results reveal that an appropriate choice of monomers and solvents leads to the formation of a supramolecular assembly solely at the interface of the solvents...
March 12, 2019: Nanoscale
https://read.qxmd.com/read/30860363/structurally-constrained-boron-nitrogen-silicon-and-phosphorus-centered-polycyclic-%C3%AF-conjugated-systems
#18
Masato Hirai, Naoki Tanaka, Mika Sakai, Shigehiro Yamaguchi
Incorporation of main group elements into the π-conjugated frameworks is a sophisticated strategy to alter the fundamental nature of the parent conjugated π-systems, giving rise to attractive electronic and photophysical properties that are otherwise inaccessible with classic carbon- or metal-based materials. Out of all π-conjugated heterocycles, those that are structurally constrained by tethered aryl substituents surrounding the main group center deserve a great deal of attention because not only do they commonly possess the maximum efficiency of π-conjugation and intermolecular interaction, but they also enjoy remarkable thermal and morphological stabilities that are especially crucial for solid-state performances...
March 12, 2019: Chemical Reviews
https://read.qxmd.com/read/30859814/tunable-optical-sensing-with-pvc-membrane-based-ion-selective-bipolar-electrodes
#19
Sutida Jansod, Eric Bakker
We show here that the response of ion-selective membrane electrodes (ISEs) based on traditional PVC membranes can be directly translated into a colorimetric readout by a closed bipolar electrode (BPE) arrangement. Because the resulting optical response is based on the turnover of the redox probe, ferroin, dissolved in a thin layer compartment, it directly indicates the potential change at the ISE in combination with a reference electrode. This class of probes measures ion activity, analogous to their ISE counterparts...
March 12, 2019: ACS Sensors
https://read.qxmd.com/read/30859808/nitrogen-n-phosphorus-p-co-doped-porous-carbon-as-metal-free-electrocatalyst-for-n2-reduction-under-ambient-conditions
#20
Pengfei Song, Li Kang, Hao Wang, Rong Guo, Rong-Min Wang
The electrocatalytic conversion of nitrogen gas at ambient conditions represents a novel approach for ammonia synthesis to the sustainable society. It is critical to understand the detail pathways and mechanism of this promising process to develop highly efficient catalyst. Herein, N, P co-doping carbon (NP-C-MOF-5) catalyst was prepared for electrocatlytic N2 reduction in acid electrolyte under ambient temperature and pressure. Experimental results showed there are two products including NH3 and N2H4•H2O on NP-C-MOF-5 cathode at -0...
March 12, 2019: ACS Applied Materials & Interfaces
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