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

Navneet Soin, Sekhar C. Ray, Sweety Sarma, Debarati Mazumder, Surbhi Sharma, Yu Fu Wang, Way Faung Pong, Susanta Sinha Roy, André M. Strydom

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

In this article, we report the modification of the electronic and magnetic properties of few-layered graphene (FLG) nanoflakes by nitrogen functionalization carried out using radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD) and electron cyclotron resonance (ECR) plasma processes. Even though the rf-PECVD N 2 treatment led to higher N-doping levels in the FLG (4.06 atomic %) as compared to the ECR process (2.18 atomic %), the ferromagnetic behavior of the ECR FLG (118.62 × 10 -4 emu/g) was significantly higher than that of the rf-PECVD FLG (0.39 × 10 -4 emu/g) and pristine graphene (3.47 × 10 -4 emu/g). Although both plasma processes introduce electron-donating N atoms into the graphene structure, distinct dominant nitrogen bonding configurations (pyridinic, pyrrolic) were observed for the two FLG types. Whereas the ECR plasma introduced 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 were further characterized using X-ray absorption near-edge spectroscopy (XANES), and X-ray and ultraviolet photoelectron spectroscopies revealed an increased electronic density of states and a significantly higher concentration of pyrrolic groups in the rf-PECVD samples. Because of the formation of reactive edge structures and pyridinic nitrogen moieties, the ECR-functionalized FLG samples exhibited highest saturation magnetization behavior with the lowest field hysteretic features. In comparison, the rf-PECVD samples displayed the lowest saturation magnetization owing to the disappearance of magnetic edge states and formation of stable nonradical-type defects in the pyrrole type structures. Our experimental results thus provide new evidence regarding the control of the magnetic and electronic properties of few-layered graphene nanoflakes through control of the plasma-processing route.

LanguageEnglish
Pages14073-14082
Number of pages10
JournalJournal Of Physical Chemistry C
Volume121
Issue number26
DOIs
Publication statusPublished - 7 Jun 2017

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Electronic properties
Graphene
Magnetic properties
graphene
Nitrogen
Tuning
tuning
Plasma enhanced chemical vapor deposition
magnetic properties
Electron cyclotron resonance
nitrogen
electron cyclotron resonance
radio frequencies
electronics
vapor deposition
Saturation magnetization
Plasmas
Ultraviolet photoelectron spectroscopy
Plasma applications

Cite this

Soin, Navneet ; Ray, Sekhar C. ; Sarma, Sweety ; Mazumder, Debarati ; Sharma, Surbhi ; Wang, Yu Fu ; Pong, Way Faung ; Roy, Susanta Sinha ; Strydom, André M. / Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes. In: Journal Of Physical Chemistry C. 2017 ; Vol. 121, No. 26. pp. 14073-14082.
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title = "Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes",
abstract = "In this article, we report the modification of the electronic and magnetic properties of few-layered graphene (FLG) nanoflakes by nitrogen functionalization carried out using radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD) and electron cyclotron resonance (ECR) plasma processes. Even though the rf-PECVD N 2 treatment led to higher N-doping levels in the FLG (4.06 atomic {\%}) as compared to the ECR process (2.18 atomic {\%}), the ferromagnetic behavior of the ECR FLG (118.62 × 10 -4 emu/g) was significantly higher than that of the rf-PECVD FLG (0.39 × 10 -4 emu/g) and pristine graphene (3.47 × 10 -4 emu/g). Although both plasma processes introduce electron-donating N atoms into the graphene structure, distinct dominant nitrogen bonding configurations (pyridinic, pyrrolic) were observed for the two FLG types. Whereas the ECR plasma introduced 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 were further characterized using X-ray absorption near-edge spectroscopy (XANES), and X-ray and ultraviolet photoelectron spectroscopies revealed an increased electronic density of states and a significantly higher concentration of pyrrolic groups in the rf-PECVD samples. Because of the formation of reactive edge structures and pyridinic nitrogen moieties, the ECR-functionalized FLG samples exhibited highest saturation magnetization behavior with the lowest field hysteretic features. In comparison, the rf-PECVD samples displayed the lowest saturation magnetization owing to the disappearance of magnetic edge states and formation of stable nonradical-type defects in the pyrrole type structures. Our experimental results thus provide new evidence regarding the control of the magnetic and electronic properties of few-layered graphene nanoflakes through control of the plasma-processing route.",
author = "Navneet Soin and Ray, {Sekhar C.} and Sweety Sarma and Debarati Mazumder and Surbhi Sharma and Wang, {Yu Fu} and Pong, {Way Faung} and Roy, {Susanta Sinha} and Strydom, {Andr{\'e} M.}",
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Soin, N, Ray, SC, Sarma, S, Mazumder, D, Sharma, S, Wang, YF, Pong, WF, Roy, SS & Strydom, AM 2017, 'Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes', Journal Of Physical Chemistry C, vol. 121, no. 26, pp. 14073-14082. https://doi.org/10.1021/acs.jpcc.7b01645

Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes. / Soin, Navneet; Ray, Sekhar C.; Sarma, Sweety; Mazumder, Debarati; Sharma, Surbhi; Wang, Yu Fu; Pong, Way Faung; Roy, Susanta Sinha; Strydom, André M.

In: Journal Of Physical Chemistry C, Vol. 121, No. 26, 07.06.2017, p. 14073-14082.

Research output: Contribution to journalArticle

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T1 - Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes

AU - Soin, Navneet

AU - Ray, Sekhar C.

AU - Sarma, Sweety

AU - Mazumder, Debarati

AU - Sharma, Surbhi

AU - Wang, Yu Fu

AU - Pong, Way Faung

AU - Roy, Susanta Sinha

AU - Strydom, André M.

N1 - Deposited in Uni of Bolton repository - evidence attached

PY - 2017/6/7

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N2 - In this article, we report the modification of the electronic and magnetic properties of few-layered graphene (FLG) nanoflakes by nitrogen functionalization carried out using radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD) and electron cyclotron resonance (ECR) plasma processes. Even though the rf-PECVD N 2 treatment led to higher N-doping levels in the FLG (4.06 atomic %) as compared to the ECR process (2.18 atomic %), the ferromagnetic behavior of the ECR FLG (118.62 × 10 -4 emu/g) was significantly higher than that of the rf-PECVD FLG (0.39 × 10 -4 emu/g) and pristine graphene (3.47 × 10 -4 emu/g). Although both plasma processes introduce electron-donating N atoms into the graphene structure, distinct dominant nitrogen bonding configurations (pyridinic, pyrrolic) were observed for the two FLG types. Whereas the ECR plasma introduced 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 were further characterized using X-ray absorption near-edge spectroscopy (XANES), and X-ray and ultraviolet photoelectron spectroscopies revealed an increased electronic density of states and a significantly higher concentration of pyrrolic groups in the rf-PECVD samples. Because of the formation of reactive edge structures and pyridinic nitrogen moieties, the ECR-functionalized FLG samples exhibited highest saturation magnetization behavior with the lowest field hysteretic features. In comparison, the rf-PECVD samples displayed the lowest saturation magnetization owing to the disappearance of magnetic edge states and formation of stable nonradical-type defects in the pyrrole type structures. Our experimental results thus provide new evidence regarding the control of the magnetic and electronic properties of few-layered graphene nanoflakes through control of the plasma-processing route.

AB - In this article, we report the modification of the electronic and magnetic properties of few-layered graphene (FLG) nanoflakes by nitrogen functionalization carried out using radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD) and electron cyclotron resonance (ECR) plasma processes. Even though the rf-PECVD N 2 treatment led to higher N-doping levels in the FLG (4.06 atomic %) as compared to the ECR process (2.18 atomic %), the ferromagnetic behavior of the ECR FLG (118.62 × 10 -4 emu/g) was significantly higher than that of the rf-PECVD FLG (0.39 × 10 -4 emu/g) and pristine graphene (3.47 × 10 -4 emu/g). Although both plasma processes introduce electron-donating N atoms into the graphene structure, distinct dominant nitrogen bonding configurations (pyridinic, pyrrolic) were observed for the two FLG types. Whereas the ECR plasma introduced 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 were further characterized using X-ray absorption near-edge spectroscopy (XANES), and X-ray and ultraviolet photoelectron spectroscopies revealed an increased electronic density of states and a significantly higher concentration of pyrrolic groups in the rf-PECVD samples. Because of the formation of reactive edge structures and pyridinic nitrogen moieties, the ECR-functionalized FLG samples exhibited highest saturation magnetization behavior with the lowest field hysteretic features. In comparison, the rf-PECVD samples displayed the lowest saturation magnetization owing to the disappearance of magnetic edge states and formation of stable nonradical-type defects in the pyrrole type structures. Our experimental results thus provide new evidence regarding the control of the magnetic and electronic properties of few-layered graphene nanoflakes through control of the plasma-processing route.

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