Carbon Pastes and Carbon Paste Electrodes - Electroanalysis with Carbon Paste Electrodes - page 30

CNTPE 1 μA

CPE

(A)

(B)

[Fe(CN) 6 ] 3/4-

-0.50 -0.25 0 +0.25 +0.50 +0.75

E [ V ] vs. Ag/AgCl

FIGURE 2.6 Cyclic.voltammetry.of.the.[Fe(CN) 6 ] 3/4− .redox.pair.at.carbon.nanotube.paste.electrode.(CNTPE).
and.common.carbon.paste.electrode.(CPE)..(A).CNTPE:.0.3.g.MW-CNTs.(NTP,.Shenzhen,.China) +.0.20.mL.
Nujol. oil. (Merck);. (B). CPE:. 0.3.g. graphite. powder. (“CR-5,”. Maziva. Tyn,. Czech. Rep.). +. 0.15.mL. Nujol. oil..
Experimental conditions :. CV,. polarization. potential. from. −0.3. to. +0.7.V. vs.. Ag/AgCl. and. back,. scan. rate:.
25.mV.·.s −1 ;.0.25.M.KCl;.c[K 4 Fe(CN) 6 ].=.0.005.mol.·.L −1 ..(Voltammograms.from.authors'.archives.)

The.second.possible.coniguration.is.then.symbolized.by. (II) Carbon Nanotube-modiied Carbon
Paste Electrodes .( CNT-CPEs ),.where.CNTs.themselves.play.the.role.of.an.additional.constituent,.
typically,.of.an.electrocatalytic.agent..These. three-component systems .consisting.of.(i).traditional.
graphite.powder,.plus.(ii).CNTs.added.in,.and.(iii).mineral.oil.can.thus.be.considered.as.the.basic.
variant.of.the.type.“II.”.And.similar.to.CNTPEs,.also.CNT-CPEs.belong.to.relatively.often.recom-
mended.carbon.paste.mixtures.(e.g.,.[372,378,384,397,431,441]).
Yet. more. complex. variants. had. come. to. the. fore. afterward,. when. originally. two-. or. three-
component.arrangements.were.combined.with.additional.constituents..This.trend.logically.led.to.
further. subvariants of CNTPEs and CNT-CPEs ,.which.was.particularly.typical.for.laboratory-made.
carbon.pastes.and.inconceivably.expanded.their.application.potential.in.the.ield..Such.a.deduction.
can. simply. be. documented. by. the. respective. scientiic. papers,. especially. those. having. appeared.
within.the.last.2.years.[410-449],.but.known.also.from.the.early.contributions.that.represent.the.irst.
actual. chemical. [360,368,370]. and. biological. [364,372,375]. modiications. of. CNT-based. pastes..
Among.typical.subvariants,.one.has

.(I-a) Chemically modiied carbon nanotube paste electrodes (CMCNTPEs) ..This.type.can.yet.
be.divided.into.two.different.subconigurations..Firstly,.the.original. two-component mix-
tures . have. the. modifying. agent. (“X”). attached. on. the. surface. (“X/CNTPE”. types);. see,.
for.example,.those.with.chemically.immobilized.luorine.compound.[396],.electrolytically.
deposited.Ni(II).complexes.[411,424].and.inorganic/organic.hybrid.polymer.[433],.or,.even-
tually,. in situ .adsorbed.chelates.[397,407])..Secondly,.the.modiier.is.manually.embedded.
into.the.carbon.paste.bulk.(“X-CNTPE”),.forming. three-component systems .with.admixed.
Cu II -molecular.wires.[373].or.Cu II -hexacyanoferrate.[436].
The.respective.electrodes.beneit.from.the.presence.of.CNT.as.the.more.effective.carbon.
moiety,.as.well.as.from.the.agent.“X”.bringing.the.desired.chemical.selectivity..In.some.
cases,. however,. the. function. of. both. CNT. and. X. can. be. mutually. integrated,. when. the.
latter.is.capable.of.further.amplifying.the.electrocatalytic.effect.of.CNTs.alone.(see,.e.g.,.
[373,432,444]).