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Bianco GV, Sacchetti A, Grande M, D'Orazio A, Milella A, Bruno G. Effective hole conductivity in nitrogen-doped CVD-graphene by singlet oxygen treatment under photoactivation conditions. Sci Rep 2022; 12:8703. [PMID: 35610345 PMCID: PMC9130222 DOI: 10.1038/s41598-022-12696-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/09/2022] [Indexed: 11/16/2022] Open
Abstract
Nitrogen substitutional doping in the π-basal plane of graphene has been used to modulate the material properties and in particular the transition from hole to electron conduction, thus enlarging the field of potential applications. Depending on the doping procedure, nitrogen moieties mainly include graphitic-N, combined with pyrrolic-N and pyridinic-N. However, pyridine and pyrrole configurations of nitrogen are predominantly introduced in monolayer graphene:N lattice as prepared by CVD. In this study, we investigate the possibility of employing pyridinic-nitrogen as a reactive site as well as activate a reactive center at the adjacent carbon atoms in the functionalized C–N bonds, for additional post reaction like oxidation. Furthermore, the photocatalytic activity of the graphene:N surface in the production of singlet oxygen (1O2) is fully exploited for the oxidation of the graphene basal plane with the formation of pyridine N-oxide and pyridone structures, both having zwitterion forms with a strong p-doping effect. A sheet resistance value as low as 100 Ω/□ is reported for a 3-layer stacked graphene:N film.
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Affiliation(s)
- Giuseppe Valerio Bianco
- Institute of Nanotechnology, CNR‑NANOTEC, Dipartimento Di Chimica, Università Di Bari, via Orabona, 4, 70126, Bari, Italy.
| | - Alberto Sacchetti
- Institute of Nanotechnology, CNR‑NANOTEC, Dipartimento Di Chimica, Università Di Bari, via Orabona, 4, 70126, Bari, Italy
| | - Marco Grande
- Institute of Nanotechnology, CNR‑NANOTEC, Dipartimento Di Chimica, Università Di Bari, via Orabona, 4, 70126, Bari, Italy.,Dipartimento di Ingegneria Elettrica e dell'Informazione, Politecnico Di Bari, via Orabona,4, 70123, Bari, Italy
| | - Antonella D'Orazio
- Dipartimento di Ingegneria Elettrica e dell'Informazione, Politecnico Di Bari, via Orabona,4, 70123, Bari, Italy
| | - Antonella Milella
- Institute of Nanotechnology, CNR‑NANOTEC, Dipartimento Di Chimica, Università Di Bari, via Orabona, 4, 70126, Bari, Italy.,Dipartimento di Chimica, Università Di Bari, via Orabona, 4, 70126, Bari, Italy
| | - Giovanni Bruno
- Institute of Nanotechnology, CNR‑NANOTEC, Dipartimento Di Chimica, Università Di Bari, via Orabona, 4, 70126, Bari, Italy
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Electronic Structure of Nitrogen- and Phosphorus-Doped Graphenes Grown by Chemical Vapor Deposition Method. MATERIALS 2020; 13:ma13051173. [PMID: 32155705 PMCID: PMC7085186 DOI: 10.3390/ma13051173] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 02/29/2020] [Accepted: 03/02/2020] [Indexed: 01/14/2023]
Abstract
Heteroatom doping is a widely used method for the modification of the electronic and chemical properties of graphene. A low-pressure chemical vapor deposition technique (CVD) is used here to grow pure, nitrogen-doped and phosphorous-doped few-layer graphene films from methane, acetonitrile and methane-phosphine mixture, respectively. The electronic structure of the films transferred onto SiO2/Si wafers by wet etching of copper substrates is studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy using a synchrotron radiation source. Annealing in an ultra-high vacuum at ca. 773 K allows for the removal of impurities formed on the surface of films during the synthesis and transfer procedure and changes the chemical state of nitrogen in nitrogen-doped graphene. Core level XPS spectra detect a low n-type doping of graphene film when nitrogen or phosphorous atoms are incorporated in the lattice. The electrical sheet resistance increases in the order: graphene < P-graphene < N-graphene. This tendency is related to the density of defects evaluated from the ratio of intensities of Raman peaks, valence band XPS and NEXAFS spectroscopy data.
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Ge H, Ye Z, He R. Raman spectroscopy of diesel and gasoline engine-out soot using different laser power. J Environ Sci (China) 2019; 79:74-80. [PMID: 30784466 DOI: 10.1016/j.jes.2018.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/26/2018] [Accepted: 11/01/2018] [Indexed: 06/09/2023]
Abstract
We studied engine-out soot samples collected from a heavy-duty direct-injection diesel engine and port-fuel injection gasoline spark-ignition engine. The two types of soot samples were characterized using Raman spectroscopy with different laser powers. A Matlab program using least-square-method with trust-region-reflective algorithm was developed for curve fitting. A DOE (design of experiments) method was used to avoid local convergence. The method was used for two-band fitting and three-band fitting. The fitting results were used to determine the intensity ratio of D (for "Defect" or "Disorder") and G (for "Graphite") Raman bands. It is found that high laser power may cause oxidation of soot sample, which gives higher D/G intensity ratio. Diesel soot has consistently higher amorphous/graphitic carbon ratio, and thus higher oxidation reactivity, compared to gasoline soot, which is reflected by the higher D/G intensity ratio in Raman spectra measured under the same laser power.
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Affiliation(s)
- Haiwen Ge
- Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
| | - Zhipeng Ye
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX 79409, USA
| | - Rui He
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX 79409, USA.
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Controlling Nitrogen Doping in Graphene with Atomic Precision: Synthesis and Characterization. NANOMATERIALS 2019; 9:nano9030425. [PMID: 30871112 PMCID: PMC6474020 DOI: 10.3390/nano9030425] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 03/06/2019] [Indexed: 12/22/2022]
Abstract
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. Different configurations of nitrogen within the carbon lattice have different electronic and chemical properties, and by controlling these dopants it is possible to either n- or p-type dope graphene, grant half-metallicity, and alter nitrogen doped graphene's (NG) catalytic and sensing properties. Thus, an understanding and the ability to control different types of nitrogen doping configurations allows for the fine tuning of NG's properties. Here we review the synthesis, characterization, and properties of nitrogen dopants in NG beyond atomic dopant concentration.
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Ma C, Liao Q, Sun H, Lei S, Zheng Y, Yin R, Zhao A, Li Q, Wang B. Tuning the Doping Types in Graphene Sheets by N Monoelement. NANO LETTERS 2018; 18:386-394. [PMID: 29266951 DOI: 10.1021/acs.nanolett.7b04249] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The doping types of graphene sheets are generally tuned by different dopants with either three or five valence electrons. As a five-valence-electrons element, however, nitrogen dopants in graphene sheets have several substitutional geometries. So far, their distinct effects on electronic properties predicted by theoretical calculations have not been well identified. Here, we demonstrate that the doping types of graphene can be tuned by N monoelement under proper growth conditions using chemical vapor deposition (CVD), characterized by combining scanning tunneling microscopy/spectroscopy, X-ray/ultraviolet photoelectron spectroscopy, Hall effect measurement, Raman spectroscopy, and density functional theory calculations. We find that a relatively low partial pressure of CH4 (mixing with NH3) can lead to the growth of dominant pyridinic N substitutions in graphene, in contrast with the growth of dominant graphitic N substitutions under a higher partial pressure of CH4. Our results unambiguously confirm that the pyridinic N leads to the p-type doping, and the graphitic N leads to the n-type doping. Interestingly, we also find that the pyridinic N and the graphitic N are preferentially separated in different domains. Our findings shed light on continuously tuning the doping level of graphene monolayers by using N monoelement, which can be very convenient for growth of functional structures in graphene sheets.
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Affiliation(s)
- Chuanxu Ma
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Qing Liao
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
- College of Chemical and Biological Engineering, Hezhou University , Hezhou, Guangxi 542899, People's Republic of China
| | - Haifeng Sun
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Shulai Lei
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Yi Zheng
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Ruoting Yin
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Aidi Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Qunxiang Li
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
| | - Bing Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, Anhui 230026, People's Republic of China
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Abstract
AbstractDue to the unique properties of graphene, single layer, bilayer or even few layer graphene peeled off from bulk graphite cannot meet the need of practical applications. Large size graphene with quality comparable to mechanically exfoliated graphene has been synthesized by chemical vapor deposition (CVD). The main development and the key issues in controllable chemical vapor deposition of graphene has been briefly discussed in this chapter. Various strategies for graphene layer number and stacking control, large size single crystal graphene domains on copper, graphene direct growth on dielectric substrates, and doping of graphene have been demonstrated. The methods summarized here will provide guidance on how to synthesize other two-dimensional materials beyond graphene.
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Cress CD, Schmucker SW, Friedman AL, Dev P, Culbertson JC, Lyding JW, Robinson JT. Nitrogen-Doped Graphene and Twisted Bilayer Graphene via Hyperthermal Ion Implantation with Depth Control. ACS NANO 2016; 10:3714-3722. [PMID: 26910346 DOI: 10.1021/acsnano.6b00252] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigate hyperthermal ion implantation (HyTII) as a means for substitutionally doping layered materials such as graphene. In particular, this systematic study characterizes the efficacy of substitutional N-doping of graphene using HyTII over an N(+) energy range of 25-100 eV. Scanning tunneling microscopy results establish the incorporation of N substituents into the graphene lattice during HyTII processing. We illustrate the differences in evolution of the characteristic Raman peaks following incremental doses of N(+). We use the ratios of the integrated D and D' peaks, I(D)/I(D') to assess the N(+) energy-dependent doping efficacy, which shows a strong correlation with previously reported molecular dynamics (MD) simulation results and a peak doping efficiency regime ranging between approximately 30 and 50 eV. We also demonstrate the inherent monolayer depth control of the HyTII process, thereby establishing a unique advantage over other less-specific methods for doping. We achieve this by implementing twisted bilayer graphene (TBG), with one layer of isotopically enriched (13)C and one layer of natural (12)C graphene, and modify only the top layer of the TBG sample. By assessing the effects of N-HyTII processing, we uncover dose-dependent shifts in the transfer characteristics consistent with electron doping and we find dose-dependent electronic localization that manifests in low-temperature magnetotransport measurements.
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Affiliation(s)
- Cory D Cress
- Electronics Science and Technology Division, U.S. Naval Research Laboratory , Washington, DC 20375, United States
| | - Scott W Schmucker
- National Research Council, U.S. Naval Research Laboratory , Washington, DC 20375, United States
| | - Adam L Friedman
- Material Science and Technology Division, U.S. Naval Research Laboratory , Washington, DC 20375, United States
| | - Pratibha Dev
- National Research Council, U.S. Naval Research Laboratory , Washington, DC 20375, United States
- Department of Physics and Astronomy, Howard University , Washington, DC 20059, United States
| | - James C Culbertson
- Electronics Science and Technology Division, U.S. Naval Research Laboratory , Washington, DC 20375, United States
| | - Joseph W Lyding
- Department of Electrical and Computer Engineering, and the Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Jeremy T Robinson
- Electronics Science and Technology Division, U.S. Naval Research Laboratory , Washington, DC 20375, United States
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Chaban VV, Prezhdo OV. Nitrogen-Nitrogen Bonds Undermine Stability of N-Doped Graphene. J Am Chem Soc 2015; 137:11688-94. [PMID: 26312575 DOI: 10.1021/jacs.5b05890] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two-dimensional alloys of carbon and nitrogen draw strong interest due to prospective applications in nanomechanical and optoelectronic devices. The stability of these chemical structures can vary greatly as a function of chemical composition and structure. The present study employs hybrid density functional theory and reactive molecular dynamics simulations to elucidate how many nitrogen atoms can be incorporated into the graphene sheet without destroying it. We conclude that (1) the C/N = 56:29 structure and all nitrogen-poorer structures maintain stability at 1000 K; (2) the stability suffers greatly in the presence of N-N bonds; and (3) distribution of electron density depends heavily on the structural pattern in the N-doped graphene. Our calculations support the experimental efforts aimed at production of highly N-doped graphene and generate important insights into the mechanisms of tuning graphene mechanical and optoelectronic properties. The theoretical prediction can be tested directly by chemical synthesis.
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Affiliation(s)
- Vitaly V Chaban
- Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo , 12231-280, São José dos Campos, SP, Brazil.,Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
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