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Electrochemistry

Pore diameter flips ORR from kinetic to transport control

Wordsworth J, Benedetti TM, Alinezhad A, et al. · Chemical science · 2019

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.

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.

How this study connects

Role on claims

Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.

  • SupportsCyclic Voltammetrymethod

    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.

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