Dynamic Modification of Fermi Energy in Single-Layer Graphene by Photoinduced Electron Transfer from Carbon Dots

Graphene (Gr)—a single layer of two-dimensional sp2 carbon atoms—and Carbon Dots (CDs)—a novel class of carbon nanoparticles—are two outstanding nanomaterials, renowned for their peculiar properties: Gr for its excellent charge-transport, and CDs for their impressive emission properties. Such features, coupled with a strong sensitivity to the environment, originate the interest in bringing together these two nanomaterials in order to combine their complementary properties. In this work, the investigation of a solid-phase composite of CDs deposited on Gr is reported. The CD emission efficiency is reduced by the contact of Gr. At the same time, the Raman analysis of Gr demonstrates the increase of Fermi energy when it is in contact with CDs under certain conditions. The interaction between CDs and Gr is modeled in terms of an electron-transfer from photoexcited CDs to Gr, wherein an electron is first transferred from the carbon core to the surface states of CDs, and from there to Gr. There, the accumulated electrons determine a dynamical n-doping effect modulated by photoexcitation. The CD–graphene interaction unveiled herein is a step forward in the understanding of the mutual influence between carbon-based nanomaterials, with potential prospects in light conversion applications.

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Comparative study of electron transfer on various graphene-metallic contacts

Modern Physics Letters B ◽

10.1142/s0217984919503846 ◽

2019 ◽

Vol 33 (31) ◽

pp. 1950384

Author(s):

Di Lu ◽

Yu-E Yang ◽

Weichun Zhang ◽

Caixia Wang ◽

Jining Fang ◽

...

Keyword(s):

Electron Transfer ◽

Single Layer ◽

Annealing Treatment ◽

Single Layer Graphene ◽

Strain Effect ◽

Graphene Surface ◽

Layer Graphene ◽

Metallic Contacts ◽

Nonuniform Strain ◽

Main Factor

We have investigated Raman spectra of the G and 2D lines of a single-layer graphene (SLG) with metallic contacts. The shift of the G and 2D lines is correlated to two different factors. Before performing annealing treatment or annealing under low temperature, the electron transfer on graphene surface is dominated by nonuniform strain effect. As the annealing treatment is enhanced, however, a suitable annealing treatment can eliminate the nonuniform strain effect where the relative work function (WF) between graphene and metal becomes a main factor to determine electronic transfer. Moreover, it is confirmed that the optimized annealing treatment can also decrease effectively the structural defect and induced disorder in graphene due to metallic contacts.

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Colorimetric and Fluorescent Dual-Modality Sensing Platform Based on Fluorescent Nanozyme

Frontiers in Chemistry ◽

10.3389/fchem.2021.774486 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yejian Wan ◽

Jingwen Zhao ◽

Xiaochun Deng ◽

Jie Chen ◽

Fengna Xi ◽

...

Keyword(s):

Large Scale ◽

Hydrothermal Process ◽

Single Layer ◽

High Sensitivity ◽

Single Layer Graphene ◽

Peroxidase Mimic ◽

Uniform Size ◽

Dual Modality ◽

Sensing Platform ◽

N Doping

Compared with natural enzymes, nanozymes based on carbonaceous nanomaterials are advantages due to high stability, good biocompatibility, and the possibility of multifunctionalities through materials engineering at an atomic level. Herein, we present a sensing platform using a nitrogen-doped graphene quantum dot (NGQD) as a highly efficient fluorescent peroxidase mimic, which enables a colorimetric/fluorescent dual-modality platform for detection of hydrogen peroxide (H2O2) and biomolecules (ascorbic acid-AA, acid phosphatase-ACP) with high sensitivity. NGQD is synthesized using a simple hydrothermal process, which has advantages of high production yield and potential for large-scale preparation. NGQD with uniform size (3.0 ± 0.6 nm) and a single-layer graphene structure exhibits bright and stable fluorescence. N-doping and ultrasmall size endow NGQD with high peroxidase-mimicking activity with an obviously reduced Michaelis–Menten constant (Km) in comparison with natural horseradish peroxidase. Taking advantages of both high nanozyme activity and unique fluorescence property of NGQD, a colorimetric and fluorescent dual-modality platform capable of detecting H2O2 and biomolecules (AA, ACP) with high sensitivity is developed as the proof-of-concept demonstration. Furthermore, the mechanisms underlying the nanozyme activity and biosensing are investigated.

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Label-Free Probing of Electron Transfer Kinetics of Single Microbial Cells on a Single-Layer Graphene via Structural Color Microscopy

Nano Letters ◽

10.1021/acs.nanolett.1c02828 ◽

2021 ◽

Vol 21 (18) ◽

pp. 7823-7830

Author(s):

Qing Xia ◽

Xueqin Chen ◽

Changhong Liu ◽

Rong-Bin Song ◽

Zixuan Chen ◽

...

Keyword(s):

Electron Transfer ◽

Single Layer ◽

Single Layer Graphene ◽

Structural Color ◽

Label Free ◽

Electron Transfer Kinetics ◽

Microbial Cells ◽

Layer Graphene ◽

Kinetics Of

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ELECTRON-IMPURITY SCATTERING IN DOPED SINGLE LAYER GRAPHENE

Modern Physics Letters B ◽

10.1142/s0217984913500334 ◽

2013 ◽

Vol 27 (05) ◽

pp. 1350033

Author(s):

DIGISH K. PATEL ◽

A. C. SHARMA ◽

S. S. Z. ASHRAF

Keyword(s):

Fermi Energy ◽

Transport Theory ◽

Single Layer ◽

Impurity Scattering ◽

Single Layer Graphene ◽

Boltzmann Transport ◽

Layer Graphene ◽

Scattering Rate ◽

Boltzmann Transport Theory ◽

Dimensional Electron Gas

We calculated electron-impurity scattering rate (ℏ/τ) as a function of quasiparticle energy (ε) for doped single layer graphene (SLG), bilayer graphene (BLG) and two-dimensional electron gas (2DEG) at zero temperature. (ℏ/τ) of SLG has been computed analytically as well as numerically. Computed results show that ℏ/τ of SLG; (a) tends to zero at ε = 0 and, (b) it exhibits peak at ≈1.6εf, where εf is Fermi energy. Contrary to this, ℏ/τ of 2DEG and BLG show their maximum values at ε = 0 and decline thereafter on increasing ε to attain a minimum at around ε equal to Fermi energy. We thus find that ℏ/τ versus ε of SLG displays an entirely different behavior than that of BLG and 2DEG, suggesting that electron-impurity scattering process in SLG sharply differs from those in BLG and 2DEG. Further, computed ℏ/τ of SLG exhibits a large variation in its magnitude over the energy range of 0 ≤ ε ≤ 3εf. Estimation of resistivity within Boltzmann transport theory involves an scattering rate averaged over all possible values of ε. It can therefore be inferred that the computation of resistivity with the use of ℏ/τ at ε = εf for comparing the computed results with experimental data can be highly misleading. Scattering rates of SLG, BLG and 2DEG are found increasing on enhancing the impurity concentration.

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Nanoscale imaging of freestanding nitrogen doped single layer graphene

Nanoscale ◽

10.1039/c4nr05385k ◽

2015 ◽

Vol 7 (6) ◽

pp. 2289-2294 ◽

Cited By ~ 15

Author(s):

Ganjigunte R. S. Iyer ◽

Jian Wang ◽

Garth Wells ◽

Michael P. Bradley ◽

Ferenc Borondics

Keyword(s):

Single Layer ◽

Single Layer Graphene ◽

Nitrogen Doped ◽

Plasma Method ◽

Layer Graphene ◽

N Doping ◽

Nanoscale Imaging

A facile low bombardment plasma method for n-doping freestanding single layer graphene.

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Kinetics of Interfacial Electron Transfer at Single-Layer Graphene Electrodes in Aqueous and Nonaqueous Solutions

Langmuir ◽

10.1021/la3042549 ◽

2013 ◽

Vol 29 (5) ◽

pp. 1683-1694 ◽

Cited By ~ 88

Author(s):

Nicole L. Ritzert ◽

Joaquín Rodríguez-López ◽

Cen Tan ◽

Héctor D. Abruña

Keyword(s):

Electron Transfer ◽

Single Layer ◽

Single Layer Graphene ◽

Interfacial Electron Transfer ◽

Nonaqueous Solutions ◽

Layer Graphene ◽

Kinetics Of

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Graphene-based tunable broadband polarizer for infrared frequency

10.21203/rs.3.rs-808726/v1 ◽

2021 ◽

Author(s):

Vishal Sorathiya ◽

Shobhit K Patel

Keyword(s):

Graphene Sheet ◽

Fermi Energy ◽

Phase Variation ◽

Single Layer ◽

Single Layer Graphene ◽

Polarization Conversion ◽

Frequency Range ◽

Infrared Frequency Range ◽

Thz Range ◽

Optical Structure

Abstract This paper proposes the tunable graphene-assisted polarizer structure which is working on the infrared frequency range. The tunable polarizer has been designed by a three-layered structure of silica, graphene, and gold. The polarizer behavior of the structure is analyzed for the frequency range of 3 to 12 THz. The tunability of the structure is analyzed for the different values of fermi energy which is tunable parameter of single-layer graphene sheet. Polarizer response is derived in terms of different performance parameters such as reflectance, phase variation, phase difference, polarization conversion rate, and effective refractive indices. Graphene-based polarizer structure is investigated for the co-polarization and cross-polarization input incident conditions to check linear to circular polarization conversion. It also shows an effective refractive index response to check the metasurface behavior of the polarizer for 3 to 12 THz range. We have observed that the polarization amplitude becomes stronger for the higher Fermi energy value of the graphene sheet. The reflection amplitude is achieved up to 90%. Results of the proposed polarizer structure can be used to design the various electro-optical structure which operates in the lower THz range.

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