Searching for magnetism in pyrrolic N-doped graphene synthesized via hydrothermal reaction

Li, Jiayuan; Li, Xinghua; Zhao, Penghui; Lei, Dangyuan; Li, Weilong; Bai, Jintao; Ren, Zhaoyu; Xu, Xinlong

doi:10.1016/j.carbon.2014.12.024

Cited by 121 publications

(80 citation statements)

References 68 publications

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“…It has also been reported that the pyrrolic N atoms bonds with the sp 3 C atoms, forming five-membered heterocylic rings which lead to a reduction in the Raman 2D band intensity. 50 This correlates well with the observed reduction in the Raman 2D band for the FLG:N(PECVD) samples ( Fig. 1(a) and Table 1), thus further confirming the enhanced formation of pyrrolic bonding for FLG:N(PECVD) samples.…”

Section: 39supporting

confidence: 85%

Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes

et al. 2017

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In this work, we report on the modification of electronic and magnetic properties of few layered graphene (FLG) nanoflakes via nitrogen functionalisation carried out using radio frequency (rf-PECVD) and electron cyclotron resonance (ECR) plasma processes. Even though the rf-PECVD N2 treatment leads to higher Ndoping levels in the FLGs (4.06 at%) as compared to the ECR process (2.18 at.%), the ferromagnetic behaviour of ECR FLG(118.62 x 10 -4 emu/gm) was significantly higher than the rf-PECVD (0.39 x 10 -4 emu/gm) and pristine graphene (3.47 x 10 -4 emu/gm). While both plasma processes introduce electron donating N-atoms in the graphene structure, distinct dominant nitrogen bonding configurations (pyridinic, pyrrolic) were observed for each FLG type. While, the ECR plasma introduces more sp 2 type nitrogen moieties, the rf-PECVD process led to the formation of sp 3 coordinated nitrogen functionalities, as confirmed through Raman measurements. The samples further characterised using X -ray absorption near edge spectroscopy (XANES) and X-ray, ultraviolet photoelectron spectroscopies revealed an increased electronic density of states and a significantly higher concentration of pyrrolic groups in the rf-PECVD samples. Due to the formation of reactive edge structures and pyridinic nitrogen moieties, the ECR functionalised FLGs expressed highest saturation magnetisation behaviour with the lowest field hysteretic features. In comparison, the rf-PECVD samples, displayed the lowest saturation magnetisation owing to the disappearance of magnetic edge states and formation of stable non-radical type defects in the pyrrole type structures. Our experimental results thus provide new evidence to control the magnetic and electronic properties of few layered graphene nanoflakes via control of the plasma-processing route.• INTRODUCTIONIntrinsic magnetism observed in materials without d-or f-electrons has attracted much interest, especially for carbon-based materials and in particular, graphene. There has been a long-standing interest in the development of ferromagnetic graphene for realizing its applications into spintronic devices via the combination of spin and charge. [1][2][3][4] The introduction of magnetic response in graphene via the introduction of edges, vacancy defects or adsorbed atoms has been investigated using both theoretical and experimental means. [1][2][3][4][5][6][7][8][9][10][11][12][13] Various theoretical studies. [3][4][5][6][7][8][9][10] have suggested that zigzag edges or point defects in graphene as the spin units should 3 carry magnetic moment with possible long-range order coupling. This coupling itself can be ferromagnetic or antiferromagnetic, depending on whether the zigzag edges or defects correspond to the same or to different hexagonal sub-lattice of the graphene lattice, respectively. At present, the intrinsic magnetic properties of finite sized graphene sheet are far from being understood, given that the magnetic signal from a finite sized graphene sheet is too weak to be detected by macr...

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Section: 39supporting

confidence: 85%

Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes

et al. 2017

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“…%) was identified to enhance ferromagnetism in highly oxidized graphene (i.e., graphene oxide) synthesized via hydrothermal reaction. 23 FM behavior has also been reported in other nitrogen-doped graphene oxide systems. 24 However, N-doped graphene oxides are unsatisfactory because a high amount of oxygen ( sp 3 functionalization) is regarded as a dominant source of magnetism, overwhelming the effects of nitrogen doping itself.…”

Section: Introductionsupporting

confidence: 52%

Doping with Graphitic Nitrogen Triggers Ferromagnetism in Graphene

et al. 2017

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Nitrogen doping opens possibilities for tailoring the electronic properties and band gap of graphene toward its applications, e.g., in spintronics and optoelectronics. One major obstacle is development of magnetically active N-doped graphene with spin-polarized conductive behavior. However, the effect of nitrogen on the magnetic properties of graphene has so far only been addressed theoretically, and triggering of magnetism through N-doping has not yet been proved experimentally, except for systems containing a high amount of oxygen and thus decreased conductivity. Here, we report the first example of ferromagnetic graphene achieved by controlled doping with graphitic, pyridinic, and chemisorbed nitrogen. The magnetic properties were found to depend strongly on both the nitrogen concentration and type of structural N-motifs generated in the host lattice. Graphenes doped below 5 at. % of nitrogen were nonmagnetic; however, once doped at 5.1 at. % of nitrogen, N-doped graphene exhibited transition to a ferromagnetic state at ∼69 K and displayed a saturation magnetization reaching 1.09 emu/g. Theoretical calculations were used to elucidate the effects of individual chemical forms of nitrogen on magnetic properties. Results showed that magnetic effects were triggered by graphitic nitrogen, whereas pyridinic and chemisorbed nitrogen contributed much less to the overall ferromagnetic ground state. Calculations further proved the existence of exchange coupling among the paramagnetic centers mediated by the conduction electrons.

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“…The strong interaction between the C and the N atoms results in a local magnetic moment of 0.56–0.84 μ B per N atom . High Curie temperature was recently reported in N‐doped graphene grown by self propagating high‐temperature synthesis, and high throughput hydrothermal method . The consistent theoretical and experimental results could be an indication that N‐doped graphene may be promising for device applications.…”

Section: Spin Generationmentioning

confidence: 67%

Prospects of spintronics based on 2D materials

Feng

Shen

Yang

et al. 2017

WIREs Comput Mol Sci

197

135

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Spintronics holds the promise for future information technologies. Devices based on manipulation of spin are most likely to replace the current silicon complementary metal‐oxide semiconductor devices that are based on manipulation of charge. The challenge is to identify or design materials that can be used to generate, detect, and manipulate spin. Since the successful isolation of graphene and other two‐dimensional (2D) materials, there has been a strong focus on spintronics based on 2D materials due to their attractive properties, and much progress has been made, both theoretically and experimentally. Here, we summarize recent developments in spintronics based on 2D materials. We focus mainly on materials of truly 2D nature, that is, atomic crystal layers such as graphene, phosphorene, monolayer transition metal dichalcogenides, and others, but also highlight current research foci in heterostructures or interfaces. In particular, we emphasize roles played by computation based on first‐principles methods which has contributed significantly in the designs of spintronic materials and devices. We also highlight challenges and suggest possible directions for further studies. WIREs Comput Mol Sci 2017, 7:e1313. doi: 10.1002/wcms.1313 This article is categorized under: Structure and Mechanism > Computational Materials Science Electronic Structure Theory > Ab Initio Electronic Structure Methods Electronic Structure Theory > Density Functional Theory

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Searching for magnetism in pyrrolic N-doped graphene synthesized via hydrothermal reaction

Cited by 121 publications

References 68 publications

Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes

Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes

Doping with Graphitic Nitrogen Triggers Ferromagnetism in Graphene

Prospects of spintronics based on 2D materials

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