Chemistry Reference
In-Depth Information
Note:
. As.indicated.in.Section.2.2.2,.the.priority.in.the.very.irst.publication.on.electroactive.carbon.
pastes.is.also.being.questioned.[2022],.as.some.review.articles.consider.[151,169].or,.at.least,.admit.
[189].that.the.aforementioned.paper.by.Barikov.et.al..[305],.originating.from.the.extensive.solid-
phase.research.in.the.former.U.S.S.R.,.was.the.true.pioneering.report.in.the.area.
In.such.a.way,.the.electrochemical.response.is.no.more.dependent.on.diffusion.but.only.on.the.
volume.of.paste.and.amount.of.electroactive.material.(at.suficiently.low.potential.scan.rates;.see.
the. following),. and. the. advantage. of. total. transformation. of. the. sample. (easily. achievable. with.
CPEEs). makes. the. method. quantitative. on. the. basis. of. the. Faraday. law. without. the. need. of. fur-
ther.calibration..Later.on,.another.progressive.method.was.developed.by.Sanchez.Batanero.et.al..
[2024].enabling.to.distinguish.between.the.electrochemical.reactions.involving.solids.(i).admixed.
or.(ii) dissolved.in.the.electrolyte.of.a.CPEE..Nowadays,.many.kinds.of.solids.(mostly.metal.oxides,.
metal.sulides,.and.related.minerals,.as.well.as.metal-based.catalysts).are.studied.using.CPEEs.(see.
the.following),.and.one.can.state.that.the.method.signiicantly.extended.the.electrochemical.char-
acterization.of.poorly.conducting.and.insoluble.solids.[306],.thus.contributing.to.broaden.the.scope.
of.solid-state.electrochemistry.(along.with.the.recently.developed.“voltammetry.of.microparticles”.
method.[307]).
7.2.2 M
ain
p
rinCiples
, C
onFiguraTions
, p
ossibiliTies
,
and
l
iMiTaTions
Studying.the.electrochemical.behavior.of.insulating.and.insoluble.compounds.requires.a.triple.con-
tact. between. these. solid. compounds,. the. electrode. surface,. and. the. electrolyte. solution. to. enable.
electron.transfer.reactions.
This. can. be. achieved. by. CPEEs. made. of. a. mixture. of. graphite. powder. (or. carbon. black),. the.
particulate.compound.of.interest,.and.a.conducting.binder.(typically.an.electrolyte.solution.[mainly.
made.from.mineral.acids.or.even.salt.solutions].or.a.conducting.polymer)..Sometimes,.a.nonconduct-
ing.binder.can.be.also.used,.but.in.that.case.the.electrochemical.reactions.are.most.often.restricted.
to.a.restricted.depth.of.the.outermost.electrode.surface..The.original.and.most.common.electrode.
coniguration.is.illustrated.in.Figure.7.2..The.paste.containing.all.the.components.(graphite,.sample.
solid,. and. binder). in. a. mixture. is. introduced. into. a. glass. or. PTFE. tube. equipped. with. a. current.
collector. and. compacted. by. pressing. onto. a. glass. frit,. which. then. serves. to. establish. the. contact.
between.the.electroactive.electrode.and.the.external.solution.while.preventing.leaching.of.the.paste.
constituents.
Two. other. conigurations,. yet. less. widespread,. have. also. been. described. (see. Figure. 7.3).. The.
irst.one.involves.the.dispersion.of.carbon.powder.and.the.sample.electroactive.solid.along.with.an.
Current collector
Glass tube
Electroactive solid
Binder
Carbon particle
Porous glass disk
FIGURE 7.2
Classical.coniguration.of.carbon.paste.electroactive.electrode.(CPEE)..A.schematic.view.
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