Differential capacitance study on the edge orientation of pyrolytic graphite and glassy carbon electrodes

Randin, Jean‐Paul; Yeager, Ernest

doi:10.1016/s0022-0728(75)80089-1

Cited by 202 publications

(126 citation statements)

References 14 publications

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“…The estimated DE (E a1 -E c1 ) values of these peaks ranged from 150 mV (pH = 1.21) to 320 mV (pH = 12.06) for a potential sweep rate n = 3 × 10 -3 V/s and increased with increasing v, which is suggestive of the quasi-reversibility of these electrode processes. Similar changes in the cathodic and anodic peak potentials with the pH of the aqueous electrolyte have been observed with other carbon electrodes (Blurton 1973;Randin and Yeager 1975;Biniak et al 2001). Figure 2 shows the changes in the shape of the first cathodic peak (c 1 ) with the pH of the external phosphate solution for a selected carbon (C180) and potential sweep rate (5 × 10 -3 V/s).…”

Section: Resultssupporting

confidence: 79%

“…Some of these functional groups (acidic, neutral and basic) exhibit electrochemical activity and participate in charging the electrical double layer (capacitance currents), specific ion adsorption ('pseudo-capacitance' current) and in faradic reactions connected with the reduction and/or oxidation of surface oxides and other active centres on the carbon surface. Studies of various carbon electrodes have provided clear evidence of the electrochemical activity of surface quinone/hydroquinone systems and the contribution of these surface oxide groups to charge-transfer reactions (Blurton 1973;Randin and Yeager 1975;Schreurs et al 1984;Leon y Leon et al 1994;Pakula et al 1995). However, the nature of these electro-active moieties and possible quantitative relationships between their surface concentration and peak currents are not yet fully understood.…”

Section: Introductionmentioning

confidence: 99%

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Changes in the Surface Chemistry and Adsorptive Properties of Active Carbon Previously Oxidised and Heat-Treated at Various Temperatures. II. Electrochemical Investigations of Surface Chemistry

Pakuła

Biniak

Świątkowski

2002

Adsorption Science & Technology

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Thermal treatment of oxidised active carbon under vacuum conditions led to changes in the chemical nature of its surface, e.g. a stepwise decrease in the total oxygen content and an increase in the pH of the carbon slurry. Annealing reduced the number of surface oxygen-containing groups and increased the overall number of basic groups. The results of the cyclic voltammetric studies analysed in this paper clearly indicate only a weak relationship between the presence and number of cathodic/anodic peaks, i.e. reduction/ oxidation of electroactive surface groups, forming during cyclisation and the degree of surface oxidation (regulated by heat treatment) of the carbon samples tested. The electrochemical behaviour of powdered carbon suggested electrooxidation of the surface of the electrode material with participation of adsorbed hydroxy ions and water molecules. The possible electrochemical reactions and mechanisms of the surface processes were discussed in order to explain the observed phenomena.

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Section: Resultssupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Changes in the Surface Chemistry and Adsorptive Properties of Active Carbon Previously Oxidised and Heat-Treated at Various Temperatures. II. Electrochemical Investigations of Surface Chemistry

Pakuła

Biniak

Świątkowski

2002

Adsorption Science & Technology

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“…The low capacitance for the basal layer is attributed to the semiconductor properties of graphite along the direction of basal orientation. Randin and Yeager [11][12][13] carried out detailed investigation for the differential capacitance on the surface of both edge and basal plane of stressed annealed pyrolytic graphite.…”

Section: Resultsmentioning

confidence: 99%

Studies of the activated carbons used in double-layer supercapacitors

Qu¹

2002

Journal of Power Sources

639

310

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The specific capacitance of activated carbons is determined by both the ratio of edge/basal orientation and the nature of functional group on the surface. The difference between the edge and the basal layers results from the semiconductive properties of basal layer. The ratio of edge/ basal orientation can be estimated by X-ray diffraction (XRD). The wettability of activated carbons is determined by the nature of functional groups on the surface. Most of the surface groups are electrochemically active. The impact of the surface groups on electrochemical performance of the activated carbon electrodes was investigated by means of various surfactant treatments. The ac impedance and constant current discharge techniques were used. Two types of surface groups which had ''capacitor-like'' or ''battery-like'' behaviors, respectively, were revealed and discussed in detail. The surface groups with ''battery-like'' behavior should be avoided. ''Non-symmetric'' electrode arrangement should be considered for a double-layer supercapacitor in order to take the advantages of pseudo-capacitance of the surface groups with ''capacitor-like'' behaviors. #

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“…4). 52 Both supercapacitors from NaOH and KOH-activated PACs also exhibited excellent cycling stability aer 5000 cycles, retaining over 95% and 92% capacitance, respectively (Fig. 6c).…”

Section: Electrochemical Propertiesmentioning

confidence: 91%

Lignin derived activated carbon particulates as an electric supercapacitor: carbonization and activation on porous structures and microstructures

Hsieh

2017

RSC Adv.

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Microporous and mesoporous particulate activated carbons (PACs) with unique hierarchical microstructures were facilely synthesized from alkali lignin via simultaneous carbonization and alkali hydroxide activation. Both NaOH and KOH activated PACs contained slit-like micropores and carbon microstructures with circular nanoplates of graphite-like basal planes and amorphous carbon clusters.The micropores broadened with increasing temperatures, holding time and alkaline hydroxides. The basal planes sizes and order were enhanced with increasing temperatures and holding time but lowering impregnation ratios, while amorphous carbon showed no particular patterns due to its much higher reactivity toward alkali hydroxides. The PACs with the highest micropore surface area and pore volume (1100 m 2 g À1, 0.43 cm 3 g À1) were obtained at 900 C, 30 min and an impregnation ratio of 1 and fabricated into electrical supercapacitors to exhibit excellent 226 F g À1 specific capacitance, 7.8 W h kg À1 energy density and 47 kW kg À1 power density as well as over 92% capacitance retention after 5000 cycles.

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Differential capacitance study on the edge orientation of pyrolytic graphite and glassy carbon electrodes

Cited by 202 publications

References 14 publications

Changes in the Surface Chemistry and Adsorptive Properties of Active Carbon Previously Oxidised and Heat-Treated at Various Temperatures. II. Electrochemical Investigations of Surface Chemistry

Changes in the Surface Chemistry and Adsorptive Properties of Active Carbon Previously Oxidised and Heat-Treated at Various Temperatures. II. Electrochemical Investigations of Surface Chemistry

Studies of the activated carbons used in double-layer supercapacitors

Lignin derived activated carbon particulates as an electric supercapacitor: carbonization and activation on porous structures and microstructures

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