Chemistry Reference
In-Depth Information
2
Carbon Pastes and Carbon
Paste Electrodes
2.1
CARBON PASTE AS A BINARY MIXTURE
2.1.1 d
eFiniTions
oF
C
arbon
p
asTe
Similarly.as.in.the.previous.chapter,.the.initial.deinitions.of.what.is.understood.under.the.term.“car-
bon.paste”.can.be.given.by.means.of.the.authentic.citation.of.descriptions.formulated.by.its.inventor,.
Adams,.in.his.three.principal.texts:
. (i). Introductory.report.“Carbon.Paste.Electrodes”.[1].“….The.(carbon).paste.is.prepared.by.
stirring.together.the.carbon.and.organic.liquid.until.the.mass.appears.uniformly.wetted..…”.
(followed.by.speciication.of.the.irst.carbon.paste.of.the.7:1.type).“….This.is.a.moderately.
thick.paste,.well.suited.for.pool.application..…”
. (ii). Review.[2],.p..71.….(with.an.introductory.paragraph.reasoning.the.introduction.of.CPEs.
for.anodic.voltammetry).“….The.carbon.paste.itself.contains.a.mixture.of.carbon.(graph-
ite).with.organic.liquid,.forming.a.typical.consistency.of.peanut.butter..…”
Note:
. In. the. context. of. this. rather. idiosyncratic. comparison,. see. also. the. cartoon. picture. in. the.
Foreword.to.this.topic.and.look.upon.its.right.upper.corner.
.(iii). Monograph.[3],.p..281.(with.an.introductory.paragraph.that.has.been.cited.in.this.topic,.
within.the.opening.sentences.of.Chapter.1).“The.carbon.paste.itself.is.prepared.by.simple.
hand.mixing.of.carbon.(usually.graphite).with.any.liquid.that.is.suficiently.nonmiscible.
with.water.to.keep.the.electrode.matrix.from.dissolving.when.immersed.in.the.solution.…”
It.can.be.added.that,.from.a.traditional.point.of.view,.a.mixture.of.carbon.(graphite).powder.with.a.
suitable.binder.(“pasting.liquid”).is.a.special.type.of.
solid carbon electrode
.[2,7,56]..The.function.
of.the.graphite.moiety.in.carbon.pastes.may.give.rise.to.some.speciic.mixtures,.when.the.resultant.
electrodes.are.similar.in.behavior.to.related.compact.carbon.materials,.such.as.
pyrolytic graphite
electrode
.(PyGE).or.
glassy carbon electrode
.(GCE),.the.latter.representing.apparently.the.most.fre-
quently.used.solid.electrode.in.electrochemical.and.electroanalytical.measurements..Nevertheless,.
due.to.the.presence.of.liquid.binder.and.because.of.its.interaction.with.graphite.particles,.carbon.
pastes.are.usually.reported.as.a.speciic.electrode.material.with.numerous.unique.properties.
Newer.deinitions.categorize.the.respective.electrodes,.carbon.paste.electrodes.(CPEs),.among.
heterogeneous carbon electrodes
.[55,69,82,83]..Such.classiication.then.comprises.almost.all.vari-
ations. of. carbon. paste-based. electrodes. and. sensors. that. have. appeared. in. the. electrochemistry.
during. the. past. decades,. including. those. being. mentioned. in. the. introductory. historic. section. as.
particular.kinds.or.conigurations.
When.considering.classical.carbon.pastes,.the.two.main.(major).components.represent.the.
moieties.with.rather.contradictory.character..This.is.given.by.the.fact.that.the.conductive.car-
bon. (graphite). usually. serves. as. the. proper. electrode. material,. whereas. liquid. binder. is. of.
insulating. character. and. acts. as. an. inert. medium,. binding. the. individual. graphite. particles.
into. a. compact. mixture.. However,. such. an. obvious. function. of. the. binder. is. accompanied. by.
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