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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.
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What does oleylamine do on these nanozymes?
Passivates the exterior so ORR proceeds only inside substrate channels.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
How much higher is channel-only specific activity at 0.95 V?
3.3 times versus exposed exteriors.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
What fractions of channels are <2 nm?
69%, 52% and 34% for etch ratios 1:1.5, 1:2.5 and 1:3.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
Under kinetic control, what does a smaller channel do?
Higher electrocatalytic performance via more confinement.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
Under mass-transport control, where does ORR occur?
Predominantly at the channel entrance.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
Does O2 concentrate in the pores?
No—uncharged O2 matches bulk regardless of diameter.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
EDL thicknesses at 0.01/0.1/1 M HClO4?
About 3 nm, 1 nm and 0.33 nm.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
What happens at 0.1 M for small vs large channels?
EDL overlap on most NZ_small channels, hence higher activity than NZ_large.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
How were kinetic currents obtained?
Koutecký–Levich extrapolation to infinite rotation rate.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
Pt–Ni synthesis ratio?
3:1 Ni(acac)2:Pt(acac)2 in oleylamine at 300 °C.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified
Why do surfactant-removed particles look worse at high η?
Internal area is counted but O2 cannot reach it.
Source: The importance of nanoscale confinement to electrocatalytic performance · DOI · quote verified