Chemistry Reference
In-Depth Information
added.that.the.respective.study.[173].has.for.the.irst.time.supported.experimentally.the.formation.of.
three.consecutive.structural.models.as.well.as.a.hypothesis.on.direct.relation.between.the.structure.of.
Bi-ilms.and.their.electroanalytical.performance..It.can.briely.be.stated.as.“the.more.developed.the.bis-
muth.crystallites.the.worse.the.properties.of.the.resultant.BiFE.with.respect.to.its.applicability.in.ESA.”
The.microdistribution.of.conductive.and.insulation.regions.on.CPE.surfaces.can.also.be.valuably.
characterized.by.means.of.STM..The.scanning.probe.technique.was.indeed.likely.to.characterize.
the.very.complex.relief.of.carbon.paste.as.“….valleys.with.hills.and.mountains.(carbon.particles).
hiding.numerous.brooks,.rivers,.and.waterfalls.(pasting.liquid)”.[172].
Note.that.observing.the.carbon.paste.surface.by.STM.resulted.in.somewhat.“smoothed”.images.
compared.with.the.higher.resolution.of.SEM.imaging..This.is.most.probably.due.to.the.fact.that.the.
STM.detector.collects.only.the.impulses.from.conductive.substrates,.and.the.overall.image.relects.
the.structure.of.the.individual.microregions.
On.the.other.hand,.SEM.can.be.an.effective.way.to.characterize.the.effect.of.chemical.modiiers.
[117,243,399,618].or.structural.alterations.after.immobilization.of.biological.tissues.[619]..This.was.
also.considerably.useful.to.follow.the.formation.preplated.metallic.ilms.to.evidence.diversities.in.the.
structure.of.palladium.deposits.[621],.mercury-[189,617],.gold-[1893],.and.bismuth.ilms.[172,622]..
CPEs.alone.and.with.electrolytically.deposited.bismuth-[620].or.palladium-[971].ilms.have.also.
been.characterized.by.AFM,.which.was.proven.to.be.effective.for.scanning.such.delicate.surfaces..
Both.intermittent.contact.and.phase-shift.scan.modes.provide.useful.information.about.nanodistribu-
tion.and.topography.as.well.as.“hard”.and.“soft”.areas.on.the.surface..For.instance,.phase.shift.scans.
of.the.same.sections.of.a.Bi-plated.CPE.depict.regions.of.high.and.uniform.phase.shift.that.cannot.
be.found.on.the.bare.CPE.and.have.to.be.attributed.to.the.newly.formed.Bi-ilm.(see.Figure.6.14).
6.5.2 o
Ther
p
hysiCoCheMiCal
T
eChniques
For
s
peCial
C
haraCTerizaTions
Various. spectroscopic. techniques. such. as.
UV-visible spectrometry and luorimetry
,.
Fourier-
transform infrared and Raman infrared spectroscopy
. (
FT-IR and RA-IR
),.
nuclear magnetic
resonance
.(
NMR
),.
mass spectrometry
.(
MS
),.
Auger spectroscopy
.(
AGS
),.
x-ray photoelectron spec-
troscopy
.(
XPS
),.as.well.as.some.other.physicochemical.methods.like.
microbalance weighing,
.iden-
tiication. by.
controlled crystallization
,.
CNS-elemental analysis
,.
nitrogen adsorption-desorption
method
,.
thermogravimetric analysis
.(
TGA
),.
x-ray diffraction
.(
XRD
),.
and x-ray luorescence
.(
XRF
).
have.been.extensively.used.to.characterize.newly.synthesized.CPE.modiiers.(see.concrete.examples.
in.[140-147,986,1049,1186,1801,1824,1833,1858]),.but.this.is.not.the.purpose.of.this.section.as.this.
relies.more.on.the.intrinsic.features.of.these.modiiers.(rather.than.those.of.the.CPE.itself),.which.
might.be.very.different.depending.on.the.modiier.type.(see.Section.4.3).
Note.that.these.techniques.can.also.be.useful.to.provide.information.on.the.(bio)chemical.stability.
of.modiiers.once.incorporated.into.or.onto.CPEs.with.respect.to.those.of.the.pristine.materials.and,.
thereby,.to.help.at.optimizing.the.modiied.CPE.preparation.in.order.to.maintain.as.good.as.possible.
the.modiier.properties.that.are.intended.to.be.exploited.for.electroanalytical.purposes..For.instance,.
UV/vis-S.and.FT-IR.were.often.applied.to.show.that.redox.proteins.as.haemoglobin.or.myoglobin.
kept.their.native.structure.when.immobilized.in.CPEs.or.CILEs.[99,664,1168,1730]..In.addition.to.the.
aforementioned.techniques,.electrochemical.impedance.spectroscopy.(EIS).was.useful.to.character-
ize.changes.in.charge.transfer.resistance;.for.example,.enhancement.of.charge.transfer.rates.has.been.
reported.for.CPE.modiied.with.TiO
2
.nanoparticles.[920].or.treated.with.surfactants.[2000].
Optical.spectroscopic.techniques.were.also.used.in.addition.to.electrochemical.ones.to.study.inter-
actions.between.one.component.in.the.paste.and.another.one.in.solution;.see,.for.example,.reaction.of.
Cu(II).with.humic.acid.[297].or.interactions.between.colchicine.and.bovine.serum.albumin.[978]..These.
works.combine.the.results.of.optical.and.electrochemical.data.usually.obtained.separately..By.contrast,.
examples.of.real.combination.of.these.techniques.are.available.through.spectroelectrochemistry.(SPEC;.
[149,1093]. or. voltabsorptometry. (VAb;. [2001]). applied. to. CPEs,. most. often. to. elucidate. the. mecha-
nisms.involved.in.the.electrochemical.response.of.the.electrode..Combination.of.spectrophotometric.
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