Electrochemistry
Pore diameter flips ORR from kinetic to transport control
Open access · cc by · source: Europe PMC
Narrower Pt–Ni nanozyme channels raise ORR activity at low overpotential by concentrating protons, but at high overpotential O2 reacts at the pore mouth.
How this study connects
Role on claims
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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.
Evidence for the claim as stated.
Study at a glance
- Design
- Animal / in-vitro — Pt–Ni nanozyme ORR with passivated exteriors plus Poisson–Nernst–Planck modelling of confined channels
- N
- Three etch-ratio channel-size distributions measured versus electrolyte concentration
- Population
- Platinum–nickel nanoparticles with isolated substrate channels
- Outcome
- Narrower confined channels raise ORR activity at low overpotential by concentrating protons; mass transport favors larger pores at high overpotential
Structured fields used in claim comparison tables when every cited study has a complete layer.
Inspect source passages
Pore diameter flips ORR from kinetic to transport control
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
Specific activity for the ORR was 3.3 times higher at 0.95 V when only channels were active.
Due to the use of oleylamine as the capping agent, the electrocatalytic reaction only proceeded within the substrate channels with the specific activity for the ORR being 3.3 times higher at 0.95 V (RHE) than when the surface outside the channels was exposed.
What does oleylamine do on these nanozymes?
the electrocatalytic reaction only proceeded within the substrate channels with the specific activity for the ORR being 3.3 times higher at 0.95 V (RHE)
Key findings
69/52/34% of channels <2 nm across three etch ratios. Specific activity 3.3× higher at 0.95 V when only interiors are active. Kinetic regime favors smaller pores; mass-transport regime favors larger pores. EDL ~3, 1, 0.33 nm at 0.01/0.1/1 M HClO4.
Methodology
Authors etched Pt–Ni particles with different channel-size distributions, passivated exteriors with oleylamine, measured ORR vs electrolyte concentration, and modelled EDL overlap and O2 depletion.
Limitations
Active-site chemical identity inside vs outside is not independently proven; model assumes protons as the confined reactant.
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