Mapping Local Quantum Capacitance and Charged Impurities in Graphene via Plasmonic Impedance Imaging

Shan, Xiaonan; Chen, Shan; Wang, Hui; Chen, Zixuan; Guan, Yan; Wang, Yixian; Wang, Shaopeng; Chen, Hong‐Yuan; Tao, Nongjian

doi:10.1002/adma.201502822

Cited by 45 publications

(50 citation statements)

References 46 publications

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“…Experimentally, except for micrometer-size exfoliated graphene [39], SPR shift induced by largesize CVD graphene is more than twice the calculated value, varying from 0.24 to 1 degree [15,[40][41][42].…”

Section: Introductionmentioning

confidence: 65%

Large graphene-induced shift of surface-plasmon resonances of gold films: Effective-medium theory for atomically thin materials

Alam

Niu

Wang

et al. 2020

Phys. Rev. Research

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Despite successful modeling of graphene as a 0.34-nm thick optical film synthesized by exfoliation or chemical vapor deposition (CVD), graphene induced shift of surface plasmon resonance (SPR) of gold films has remained controversial. Here we report the resolution of this controversy by developing a clean CVD graphene transfer method and extending Maxwell-Garnet effective medium theory (EMT) to 2D materials. A SPR shift of 0.24º is obtained and it agrees well with 2D EMT in which wrinkled graphene is treated as a 3-nm graphene/air layered composite, in agreement with the average roughness measured by atomic force microscope. Because the anisotropic built-in boundary condition of 2D EMT is compatible with graphene's optical anisotropy, graphene can be modelled as a film thicker than 0.34-nm without changing its optical property; however, its actual roughness, i.e., effective thickness will significantly alter its response to strong out-of-plane fields, leading to a larger SPR shift.

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Section: Introductionmentioning

confidence: 65%

Large graphene-induced shift of surface-plasmon resonances of gold films: Effective-medium theory for atomically thin materials

Alam

Niu

Wang

et al. 2020

Phys. Rev. Research

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“…2 In recent years, carbon nanomaterials such as carbide-derived carbons and graphene have become popular as supercapacitor electrode materials due to their good conductivity and high specific surface area. [2][3][4][5][6][7][8][9] Graphene, unlike a traditional metal electrode, has a different capacitive performance due to its quantum capacitance, [10][11][12] which is caused by its limited density of states (DOS) near the Fermi level.…”

Section: Introductionmentioning

confidence: 99%

Enhancing graphene capacitance by nitrogen: effects of doping configuration and concentration

Zhan

Zhang

Cummings

et al. 2016

Phys. Chem. Chem. Phys.

123

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Recent experiments have shown that nitrogen doping enhances capacitance in carbon electrode supercapacitors. However, a detailed study of the effect of N-doping on capacitance is still lacking. In this paper, we study the doping concentration and the configuration effect on the electric double-layer (EDL) capacitance, quantum capacitance, and total capacitance. It is found that pyridinic and graphitic nitrogens can increase the total capacitance by increasing quantum capacitance, but pyrrolic configuration limits the total capacitance due to its much lower quantum capacitance than the other two configurations. We also find that, unlike the graphitic and pyridinic nitrogens, the pyrrolic configuration's quantum capacitance does not depend on the nitrogen concentration, which may explain why some capacitance versus voltage measurements of N-doped graphene exhibit a V-shaped curve similar to that of undoped graphene. Our investigation provides a deeper understanding of the capacitance enhancement of the N-doping effect in carbon electrodes and suggests a potentially effective way to optimize the capacitance by controlling the type of N-doping.

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“…The double layer charging current on graphene is also much smaller than that on gold because graphene has a small surface capacity compared to gold . Third, the optical transmission of monolayer graphene is much less sensitive to potential than that of the gold film (see Figure S1 in the Supporting Information), which further minimizes the interference from the optical properties of the substrate material. Finally, a monolayer of graphene is optically transparent, allowing clear optical imaging of the nanowires.…”

Section: Figurementioning

confidence: 99%

Determining Electrochemical Surface Stress of Single Nanowires

Wang

Shan

et al. 2017

Angew Chem Int Ed

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Electrochemical surface stress is important in nanomaterials because of their large surface-to-volume ratios, which lead to unique mechanical and electrocatalytic properties, but directly measuring this quantity has been challenging. Here we report on experimental determination of the surface stress, and associated electrochemical processes of a single gold nanowire with an optical imaging technique. We show that surface stress changes linearly and reversibly with the potential between 0 and 0.8 V versus Ag/AgCl, but abruptly with large hysteresis, associated with the oxidation and reduction of the nanowire, between 0.8 and 1.5 V. The potential derivative of the surface stress closely resembles the cyclic voltammograms. We described the observations in terms of anion adsorption and surface oxidation/reduction. This work demonstrates a new approach to study electrochemical processes and the associated surface stress changes of nanomaterials.

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Mapping Local Quantum Capacitance and Charged Impurities in Graphene via Plasmonic Impedance Imaging

Abstract: Local quantum capacitance of graphene is imaged with plasmonics-based electrical impedance microscopy, from which the local density and polarity of charged impurities, electron and hole puddles associated with the charged impurities, and the density of the impurity states are determined.

Cited by 45 publications

References 46 publications

Large graphene-induced shift of surface-plasmon resonances of gold films: Effective-medium theory for atomically thin materials

Large graphene-induced shift of surface-plasmon resonances of gold films: Effective-medium theory for atomically thin materials

Enhancing graphene capacitance by nitrogen: effects of doping configuration and concentration

Determining Electrochemical Surface Stress of Single Nanowires

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