Research method
Cyclic Voltammetry
6 studies
Cyclic voltammetry sweeps an electrode potential back and forth and records current. Peak position, shape and scan-rate dependence report how fast electron transfer is, whether a couple is reversible, and — in catalytic waves — how a dissolved or surface species turns over substrate. In this library CV is used both as a bulk diagnostic (a macroscale ITO electrode, a molecular catalyst, a battery composite) and as thousands of nanoscale voltammograms in a scanning droplet cell.
Electrochemists reach for CV when they need a kinetic fingerprint of a surface or a molecule rather than a single amperometric number. It answers 'how does current respond as we drive this couple?' Its main limitation is that the voltammogram is specific to the electrolyte, wetting, and length scale of the measurement: a macroscale 'blocked electrode' story can fail when the same couple is mapped at 50 nm.
Studies
6
Findings
4
6 supporting · 0 challenging · 0 qualifying citations
Open tensions
2
Currently
What we know
- Nanoscale SECCM voltammetry can overturn a blocked-electrode reading of ITO. With a 50 nm pipette, every landing oxidised ferrocenedimethanol; only 0.2% of area was fully reversible (k⁰ ≥ 1 cm s⁻¹), 85.2% had mean k⁰ = 4.2×10⁻² cm s⁻¹, and a weighted average k⁰ ≈ 3.61×10⁻² cm s⁻¹. Film resistance, not inert patches, likely dominates the macroscale CV.
- The same CV family is used to quantify a practical problem — droplet wetting — before mapping catalysis. Unmodified 1 M KOH SECCM droplets wet about 7× the tip diameter; 0.1% PVP cut the wetting factor to about 1.2×, enabling grain-resolved OER on polycrystalline Pt in which (110) and (111) outrank (100) at pH 13.8, unlike common acidic rankings.
- Molecular CV (with complementary methods) assigns ligand-centered redox and catalytic overpotential. Pyrazine reservoirs on cobalt PY4/PY3PZ complexes improved HER overpotential by about 200 mV versus pyridine analogues; Zn(II) controls helped separate ligand from metal redox. Device-level solar-to-hydrogen efficiency is not the claim.
- CV also appears as a supporting characterisation of materials and mechanisms: pore-confined Pt–Ni ORR, a stibnite/carbon sodium-ion composite, and a photoredox trifluoromethylation where CV of 9,10-phenanthrenequinone sits beside EPR and ¹⁸O labelling. Those papers are not primarily about teaching CV, but they still use a voltammogram as evidence.
Largest unresolved question
Length scale and electrolyte change the ranking CV is allowed to report. ITO looks partly inert in macroscale CV and uniformly active at 50 nm; Pt OER facet order in PVP-containing pH 13.8 KOH is not the acidic single-crystal order. Quoting a k⁰ or a facet ranking without the length scale and wetting chemistry is the disagreement.
Common misconceptions
If a macroscale CV looks irreversible, most of the electrode must be dead.
SECCM at ~50 nm found the entire ITO surface active for an outer-sphere couple; only 0.2% was fully reversible, and the authors argue film resistance dominates the macro k⁰ rather than a sparse-site picture.
Facet activity rankings are a property of the metal, independent of pH and of how the droplet sits on the surface.
In concentrated KOH, SECCM wetting without PVP can be ~7× the tip diameter, and with PVP the OER ranking on Pt grains is (110)/(111) above (100) at pH 13.8, unlike common acidic rankings.
A voltammogram of a photocatalyst proves the synthetic mechanism in the flask.
The enyne oxy-trifluoromethylation paper uses CV of PQ among EPR, ¹⁸O labelling, and DFT; H₂ is inferred from NMR rather than quantified by GC. CV is one constraint, not the whole mechanism.
Related
Claim ledger
What the evidence shows
Drawn from 6 studies in this library. Mix labels say which citation roles are present; they are not a strength score. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope.
Nanoscale SECCM voltammetry can overturn a blocked-electrode reading of ITO. With a 50 nm pipette, every landing oxidised ferrocenedimethanol; only 0.2% of area was fully reversible (k⁰ ≥ 1 cm s⁻¹), 85.2% had mean k⁰ = 4.2×10⁻² cm s⁻¹, and a weighted average k⁰ ≈ 3.61×10⁻² cm s⁻¹. Film resistance, not inert patches, likely dominates the macroscale CV.
The same CV family is used to quantify a practical problem — droplet wetting — before mapping catalysis. Unmodified 1 M KOH SECCM droplets wet about 7× the tip diameter; 0.1% PVP cut the wetting factor to about 1.2×, enabling grain-resolved OER on polycrystalline Pt in which (110) and (111) outrank (100) at pH 13.8, unlike common acidic rankings.
Molecular CV (with complementary methods) assigns ligand-centered redox and catalytic overpotential. Pyrazine reservoirs on cobalt PY4/PY3PZ complexes improved HER overpotential by about 200 mV versus pyridine analogues; Zn(II) controls helped separate ligand from metal redox. Device-level solar-to-hydrogen efficiency is not the claim.
CV also appears as a supporting characterisation of materials and mechanisms: pore-confined Pt–Ni ORR, a stibnite/carbon sodium-ion composite, and a photoredox trifluoromethylation where CV of 9,10-phenanthrenequinone sits beside EPR and ¹⁸O labelling. Those papers are not primarily about teaching CV, but they still use a voltammogram as evidence.
- Pore diameter flips ORR from kinetic to transport control
- Stibnite in carbon sheets stores sodium better
- PQ and water oxy-trifluoromethylate enynes
Study Role Design N Population Outcome Pore diameter flips ORR from kinetic to transport control Supports Animal / in-vitroPt–Ni nanozyme ORR with passivated exteriors plus Poisson–Nernst–Planck modelling of confined channels Three etch-ratio channel-size distributions measured versus electrolyte concentration Platinum–nickel nanoparticles with isolated substrate channels Narrower confined channels raise ORR activity at low overpotential by concentrating protons; mass transport favors larger pores at high overpotential Stibnite in carbon sheets stores sodium better Supports OtherNatural Sb2S3 on sulfur-doped carbon sheets tested as a sodium-ion anode Battery materials half-cell study — no sample N Sb2S3/SCS composite electrodes in Na-ion half-cells Reversible capacity and cycling retention versus raw stibnite PQ and water oxy-trifluoromethylate enynes Supports Animal / in-vitroPhenanthrenequinone photoredox cascade on 1,6-enynes with 18O-water, EPR, and DFT Substrate-scope benzofurans, benzothiophenes, and indoles rather than a single N Phenolic 1,6-enynes with Langlois’ CF3SO2Na and water Visible-light, metal-free cascade trifluoromethylates and oxidizes 1,6-enynes, with water supplying the ketone oxygen
Debates
Tensions and limits
Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes.
Length scale and electrolyte change the ranking CV is allowed to report. ITO looks partly inert in macroscale CV and uniformly active at 50 nm; Pt OER facet order in PVP-containing pH 13.8 KOH is not the acidic single-crystal order. Quoting a k⁰ or a facet ranking without the length scale and wetting chemistry is the disagreement.
Length scale and electrolyte change the ranking CV is allowed to report. ITO looks partly inert in macroscale CV and uniformly active at 50 nm; Pt OER facet order in PVP-containing pH 13.8 KOH is not the acidic single-crystal order. Quoting a k⁰ or a facet ranking without the length scale and wetting chemistry is the disagreement.
Study Role Design N Population Outcome ITO electrodes are active everywhere at 50 nm Supports OtherSECCM nanoscale LSV mapping of ITO with Butler–Volmer kinetic fitting Thousands of landing sites on ITO — surface mapping, not a cohort N Indium tin oxide electrode surfaces Spatial distribution of heterogeneous electron-transfer rate constants PVP lets SECCM map Pt OER in concentrated KOH Supports OtherSECCM meniscus wetting control with PVP in 1 M KOH and correlative EBSD OER mapping on Pt Electrochemical microscopy method — no sample N Polycrystalline Pt grains probed by alkaline SECCM Facet-dependent OER currents after wetting-factor control
PaperFren reads this as a limit on how far one study travels — different assays, populations, or outcomes — not a forced fight between papers.
A catalytic wave in a molecular CV and a battery half-cell CV are different deliverables. The cobalt HER paper reports overpotential versus a pyridine control; the stibnite composite reports capacity retention versus sodium metal (455.8 mA h g⁻¹ after 100 cycles), not a molecular k⁰. Calling both 'the CV showed it was active' erases that.
A catalytic wave in a molecular CV and a battery half-cell CV are different deliverables. The cobalt HER paper reports overpotential versus a pyridine control; the stibnite composite reports capacity retention versus sodium metal (455.8 mA h g⁻¹ after 100 cycles), not a molecular k⁰. Calling both 'the CV showed it was active' erases that.
- Pyrazine reservoirs that lower cobalt HER overpotential
- Stibnite in carbon sheets stores sodium better
Study Role Design N Population Outcome Pyrazine reservoirs that lower cobalt HER overpotential Supports OtherCobalt PY4/PY3PZ complexes for aqueous electrocatalytic and photoredox H2 evolution with DFT Molecular catalysis study — no sample N Cobalt redox-active ligand complexes in aqueous catalytic assays Overpotential and H2 evolution as a function of pendant pyrazine redox reservoirs Stibnite in carbon sheets stores sodium better Supports OtherNatural Sb2S3 on sulfur-doped carbon sheets tested as a sodium-ion anode Battery materials half-cell study — no sample N Sb2S3/SCS composite electrodes in Na-ion half-cells Reversible capacity and cycling retention versus raw stibnite
PaperFren reads this as a limit on how far one study travels — different assays, populations, or outcomes — not a forced fight between papers.
Timeline
How understanding moved
Study years are when the paper was published. Evidence edits are dated changes to this page's claims. Explanations are when PaperFren added a Discovery — not a claim that the science happened that day.
2026
Concept page published
Cyclic Voltammetry
Change log
What changed
Dated edits to this page's evidence: studies added or removed from a claim, claims added or withdrawn, and new explanations tagged here. Coverage edits are distinct from reviewed research changes and corrections. Dates record PaperFren updates; study publication dates appear in the timeline.
- Coverage updated · Concept page published
Papers
6 studies in this library bear on Cyclic Voltammetry, ordered by citations.
- PQ and water oxy-trifluoromethylate enynes
Sunlight-excited phenanthrenequinone turns Langlois’ CF3SO2Na into CF3· and uses water as the oxygen atom to build CF3 benzofurans, benzothiophenes and indoles.
- Pyrazine reservoirs that lower cobalt HER overpotential
Moving a redox-active pyrazine on a cobalt polypyridine ligand cuts hydrogen-evolution overpotential by about 200 mV versus pyridine analogues in water.
- Pore diameter flips ORR from kinetic to transport control
Narrower Pt–Ni nanozyme channels raise ORR activity at low overpotential by concentrating protons, but at high overpotential O2 reacts at the pore mouth.
- ITO electrodes are active everywhere at 50 nm
Thousands of nanoscale voltammograms show every ITO patch oxidizes ferrocenedimethanol; only 0.2% is fully reversible, and the old sparse-site model fails.
- Stibnite in carbon sheets stores sodium better
Natural Sb2S3 anchored on sulfur-doped carbon sheets delivers much higher reversible sodium-storage capacity and cycle retention than raw stibnite.
- PVP lets SECCM map Pt OER in concentrated KOH
A little polyvinylpyrrolidone stops alkaline SECCM droplets from spreading, enabling single-grain OER maps that rank Pt(110)/(111) above (100) at pH 13.8.
Compare studies
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Questions
What is still open
Length scale and electrolyte change the ranking CV is allowed to report. ITO looks partly inert in macroscale CV and uniformly active at 50 nm; Pt OER facet order in PVP-containing pH 13.8 KOH is not the acidic single-crystal order. Quoting a k⁰ or a facet ranking without the length scale and wetting chemistry is the disagreement.
A catalytic wave in a molecular CV and a battery half-cell CV are different deliverables. The cobalt HER paper reports overpotential versus a pyridine control; the stibnite composite reports capacity retention versus sodium metal (455.8 mA h g⁻¹ after 100 cycles), not a molecular k⁰. Calling both 'the CV showed it was active' erases that.
Ask PaperFren about Cyclic Voltammetry
Study this conceptflashcards and short-answer questions
How can every ITO landing be electrochemically active while only 0.2% of the area is 'reversible'?
Activity means FcDM is oxidised at that 50 nm site. Reversibility here means k⁰ ≥ 1 cm s⁻¹. Most of the surface is slower (mean k⁰ 4.2×10⁻² cm s⁻¹; 14.6% much slower still), so a macroscale CV can look sluggish without large inert patches.
Why did the alkaline SECCM paper have to measure wetting with Fc(MeOH)₂ voltammetry before trusting an OER map?
If the droplet spreads to ~7× the tip diameter, the current is no longer from a single grain. PVP reduced the wetting factor to ~1.2×, which is what makes a grain-resolved OER ranking possible.
What control lets the cobalt HER paper claim that pyrazine is a redox reservoir rather than just a better σ-donor ligand?
Zn(II) analogues, which are redox-inactive at the metal, help assign ligand-centered couples; isomer position of pyrazine then changes HER overpotential by ~200 mV versus pyridine ligands without those reservoirs.
Name one thing SECCM CV can do that a rotating-disk Tafel experiment on a single crystal typically cannot, and one thing it cannot replace.
It can map thousands of local voltammograms across grains or ITO patches and correlate them with structure (EBSD). It does not, in the PVP/KOH paper, replace a single-crystal RDE Tafel study without polymer additive, and the ITO study uses one outer-sphere couple on one ITO grade.