Density of the electronic states of graphite:  derivation from differential capacitance measurements

Gerischer, H.; Scherson, Daniel Alberto; Storck, W.

doi:10.1021/j100291a049

Cited by 217 publications

(246 citation statements)

References 5 publications

(8 reference statements)

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“…The mean minimum values of C EDL vary over the limited range from 2.5 to 3.5 mF cm À 2 with layer number n, and are close to the values measured on the basal plane of highly oriented pyrolytic graphite (HOPG) (Fig. 3b) 27,28 . On the other hand, the magnitudes of the slopes of the left and right arms of the C EDL À V EDL , which correspond to electron-and hole-doped regions, drop by about 74% when stacked graphene layer number increases from one to five, approaching values measured with HOPG ( Fig.…”

Section: Article Nature Communications | Doi: 101038/ncomms4317supporting

confidence: 77%

“…Previously small C A values on carbon electrodes have been explained by invoking a space charge capacitance 18,22,27,28 , representing spread of induced electrode charge into the bulk, in series with a Helmholtz capacitance C H , representing the Helmholtz layer 29 located on the liquid side of the interface, between the electrolyte and the bulk solid (Fig. 4a).…”

Section: Article Nature Communications | Doi: 101038/ncomms4317mentioning

confidence: 99%

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Capacitance of carbon-based electrical double-layer capacitors

et al. 2014

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Experimental electrical double-layer capacitances of porous carbon electrodes fall below ideal values, thus limiting the practical energy densities of carbon-based electrical double-layer capacitors. Here we investigate the origin of this behaviour by measuring the electrical double-layer capacitance in one to five-layer graphene. We find that the capacitances are suppressed near neutrality, and are anomalously enhanced for thicknesses below a few layers. We attribute the first effect to quantum capacitance effects near the point of zero charge, and the second to correlations between electrons in the graphene sheet and ions in the electrolyte. The large capacitance values imply gravimetric energy storage densities in the single-layer graphene limit that are comparable to those of batteries. We anticipate that these results shed light on developing new theoretical models in understanding the electrical double-layer capacitance of carbon electrodes, and on opening up new strategies for improving the energy density of carbon-based capacitors.

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Section: Article Nature Communications | Doi: 101038/ncomms4317supporting

confidence: 77%

Section: Article Nature Communications | Doi: 101038/ncomms4317mentioning

confidence: 99%

Capacitance of carbon-based electrical double-layer capacitors

et al. 2014

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“…42,44 This is not the case for a perfect metal. Thus, it is possible that any applied voltage is not completely dropped across the tip and HOPG surface.…”

Section: Adsorption Dipole Moment and Screeningmentioning

confidence: 99%

Electrostatic Force Microscopy Characterization of Trioctylphosphine Oxide Self-assembled Monolayers on Graphite

2000

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We have studied the self-assembling behavior of trioctylphosphine oxide (TOPO) on a highly oriented pyrolytic graphite surface. TOPO forms stripe-like structures in registry with the underlying graphite lattice. Using electrostatic force microscopy, we have also measured the charge, dipole, and dielectric constant of these monolayer films. The crystalline stripe phase has a net positive charge of about 2 × 10 -5 electron charge per TOPO molecule. The surface dipole due to adsorption is extremely small; this result implies that the dipole moment of TOPO is oriented parallel to the surface. Perfect image charges are not formed inside the graphite.

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“…The fact that the ions and the polymer chains cannot approach a (charged) surface to infinite proximity due to their finite size can be taken into account by introducing the concept of a Stern layer, into which the charge of the ions and the polymer chains cannot penetrate [41]. The Stern layer has a capacitance C St (F/m 2 ) and the decrease of the electrostatic potential across the Stern layer is inversely proportional to the capacitance:…”

Section: Stern Layermentioning

confidence: 99%

Adsorption of charged and neutral polymer chains on silica surfaces: The role of electrostatics, volume exclusion, and hydrogen bonding

2015

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We develop an off-lattice (continuum) model to describe the adsorption of neutral polymer chains and polyelectrolytes to surfaces. Our continuum description allows taking excluded volume interactions between polymer chains and ions directly into account. To implement those interactions, we use a modified hard-sphere equation of state, adapted for mixtures of connected beads. Our model is applicable to neutral, charged, and ionizable surfaces and polymer chains alike and accounts for polarizability effects of the adsorbed layer and chemical interactions between polymer chains and the surface. We compare our model predictions to data of a classical system for polymer adsorption: neutral poly(N -vinylpyrrolidone) (PVP) on silica surfaces. The model shows that PVP adsorption on silica is driven by surface hydrogen bonding with an effective maximum binding energy of about 1.3 k B T per PVP segment at low pH. As the pH increases, the Si-OH groups become increasingly dissociated, leading to a lower capacity for H bonding and simultaneous counterion accumulation and volume exclusion close to the surface. Together these effects result in a characteristic adsorption isotherm, with the adsorbed amount dropping sharply at a critical pH. Using this model for adsorption data on silica surfaces cleaned by either a piranha solution or an O 2 plasma, we find that the former have a significantly higher density of silanol groups.

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Density of the electronic states of graphite: derivation from differential capacitance measurements

Cited by 217 publications

References 5 publications

Capacitance of carbon-based electrical double-layer capacitors

Capacitance of carbon-based electrical double-layer capacitors

Electrostatic Force Microscopy Characterization of Trioctylphosphine Oxide Self-assembled Monolayers on Graphite

Adsorption of charged and neutral polymer chains on silica surfaces: The role of electrostatics, volume exclusion, and hydrogen bonding

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