Carbon Pastes and Carbon Paste Electrodes - Electroanalysis with Carbon Paste Electrodes - page 27

be.also.(i).carbon.cement.[324].that.can.be.packed.as.a.carbon.paste.into.a.special.electrode.holder,.or.
recently.quite.popular.(ii).carbon.ilms;.see,.e.g.,.[325].).As.noted.in.historical.introduction,.carbon.
inks.and.SPEs.are.connected.with.carbon.pastes.and.CPEs.mainly.in.the.developmental.stage—as.
practical.realization.of.laboratory.testing.of.CPEs.and.CMCPEs.(see.also.[326,327])..Today,.SPEs.
represent.a.well-established.and.large.group.of.modern.sensors.with.a.number.of.speciic.features.
(planar.coniguration,.miniature.size,.possible.industrial.production,.disposable.character,.and.high.
promise.for.routine.analysis),.positioning.their.presentation.already.beyond.the.scope.of.this.topic.
In.contrast.to.efforts.in.seeking.new.alternate.binders,.there.is.a.series.of.related.reports.[328-331].
on.“pseudo-carbon.paste.electrodes”.(p-CPEs).whose.coniguration.misses.the.usual.liquid.moiety,.
replacing. it. with. a. polymer.. More. speciically,. such. porous. p-CPEs. can. be. fabricated. by. mixing.
graphite.powder,.pyrrole.(as.a.monomer.actually.forming.the.paste-like.mixture),.and.polystyrene.
microspheres. (as. a. template).. After. catalyzed. polymerization,. the. latter. is. removed. to. yield. the.
resultant. porous. structure. (with. pores. of. 2-5.μm. in. diameter).. Reportedly. [328,331],. the. surface.
area.of.such.( n )P-p-CPE.is.greatly.increased.(from.ca..10.up.to.60.m 2 .·.g −1 ),.beneiting—similarly.
as.for.typical.CPEs—from.an.easy.and.simple.preparation.(when.no.binding.agents.needed),.easy.
preservation.and.renewal,.and.mainly.form.being.highly.hydrophobic,.thus.exhibiting.a.substantial.
afinity.for.selective.accumulations.of.lipophilic.organic.compounds.[329].
2.2.3 n eW T ypes oF C arbon p asTe e leCTrodes
In. fact,. each. CPE. prepared. from. the. materials. that. have. been. classiied. earlier. as. “new. types. of.
carbon”. or. “new. binders”. (see. Sections. 2.1.2. and. 2.1.3. or. [95,96,113,114,116,117,119-121,139,.
193-204].and.[238,239]).can.also.be.considered.as.novel.CPEs..In.these.cases,.however,.the.respec-
tive. electrodes. represent. more. or. less. the. irst. prototypes. existing. so. far. in. a. few. exemplars. and.
mostly. undergoing. the. basic. characterization. only,. that. is,. without. wider. appearance. and. typical.
applications.
Into.this.category,.it.is.possible.to.add.yet.another.quintet.of.reports.[332-336].on.newly.proposed.
carbon. paste-based. electrodes. that. can. be. jointly. called. carbon paste ilm electrodes . ( CPFEs ).
and. for. which. the. resultant. coniguration. has. been. reduced. to. a. very. thin. ilm/layer. of. carbon.
(paste).attached.to.a.compact.electrode.support,.speciically,.Ni-Cr.alloy.[332].and.common.GCEs.
[204,333,334]..The.paste.itself.is.either.“super.thin.ilm”.(STF;.[332]).accomplished.by.inlaying.a.
mixture.of.two.traditional.constituents.(and.the.corresponding.electrode.denoted.as.STF-CPE).or.
composed.entirely.from.alternate.CP-components,.which.is.the.case.of.two.mixtures.MW-CNTs.+.
(RT)IL.[333,334].and.GR.+.(RT)IL.[204],.the.latter.containing.besides.GR.and.ionic.liquid.(of.the.
Q + PF 6 − .type).also.an.additional.solid.binder.with.a.biological.sensing.element.
A. speciic. variant. of. these. ilm. arrangements. is. also. concerned. in. two. fresh. contributions,.
describing. novel. two-dimensional. carbon. materials,. “graphite. oxide”. [335]. or. “graphene. oxide”.
[336],.respectively..The.irst.one.was.prepared.by.chemical.oxidation.of.natural.graphite.powder.and.
then.used.to.modify.the.surface.of.the.supporting.electrode..In.approximation,.this.approach.leads.
to.the.same.effect.like.electrolytic.activation.of.the.surface.of.some.carbon.electrodes,.including.
CPEs.(see.[83,175].and.also.the.following.text,.in.the.next.chapter),.when.one.can.also.obtain.a.very.
thin.and.sensitive.layer.of.oxidized.carbon.particles.whose.presence.totally.alter.the.surface.states.
(characteristics).of.an.electrode.treated.in.this.way.[68]..With.respect.to.the.fact.that.graphene-oxide.
ilm.could.be.electrolytically.deposited.directly.onto.the.GCE.surface—that.is,.without.any.inter-
step.needed.for.preparation.of.oxidized.graphite.particles.and.its.subsequent.attachment.[336]—it.
is.questionable,.however,.whether.or.not.these.speciic.conigurations.are.to.be.classiied.as.carbon.
paste-.or.carbon.paste-like.electrodes..Rather,.it.seems.that.their.right.ranking.is.among.chemically.
modiied.carbonaceous.substrates.
Within. a. wide. variety. of. the. new. conigurations,. there. are. three. signiicant. categories.
of. (i) DPEs,. (ii). CNTPEs,. and. (iii). CILEs. that. have. been. applied. more. extensively,. which. is.