ELECTRODE SPECIFICATION
OER OVERPOTENTIAL260 mV OER Overpotential at 100 mA/cm2
Measured on our bifunctional NiCo electrode in 30 wt% KOH at 100 mA/cm2 without any IR correction. The same coated electrode operates as both anode and cathode in an AEM cell.
OER OVERPOTENTIAL
TESTBEDThis spec
OER OVERPOTENTIAL
HER overpotential
@ 100 mA/cm² (no IR)
OER overpotential
@ 100 mA/cm² (no IR)
Cell @ 0.5 A/cm² / 60 °C
91.4% efficiency
1000-hour drift
@ 0.5 A/cm² / 40 °C
What OER overpotential measures
The oxygen evolution reaction (OER) is the anode-side half-reaction in water electrolysis: hydroxide ions release electrons to produce oxygen and water. OER is the more energy-demanding of the two half-reactions because of the four-electron transfer required to form O-O bonds. The overpotential is the extra voltage above the thermodynamic minimum required to drive OER at a given current density.
Our bifunctional NiCo electrode is a bi-metallic transition-metal catalyst deposited on Ni foam (100 to 1000 cm2) by electroless deposition. At 100 mA/cm2 in 30 wt% KOH, the OER overpotential is 260 mV. This measurement was taken without any IR correction.
- Reaction: 4 OH- -> O2 + 2 H2O + 4 e- (anode side)
- Overpotential: 260 mV at 100 mA/cm2 (no IR correction)
- Electrolyte: 30 wt% KOH
- Same electrode also serves as HER cathode at 80 mV overpotential
OER @ 100 mA/cm2
HER @ 100 mA/cm2
Cell @ 0.5 A/cm2, 60 C
OER as the dominant half-cell loss
OER overpotential is typically the larger of the two half-cell contributions in alkaline water electrolysis because the kinetics of O-O bond formation are slow. The 260 mV OER overpotential on our bifunctional NiCo electrode is the measured value at 100 mA/cm2 in 30 wt% KOH, reported as-measured without IR correction.
At cell level with our bifunctional NiCo electrode on both sides and a commercial Zirfon separator (500 um), the AEM cell logs 0.5 A/cm2 at 1.62 V at 60 deg C (91.4% efficiency). The OER overpotential at the anode is one of the components that builds up to that cell voltage; HER overpotential, separator resistance, and bulk electrolyte resistance are the others.
Stability of the OER side over 1000 hours
OER conditions are oxidizing; many catalysts degrade more rapidly on the anode side than the cathode side. The 1000-hour chronopotentiometry on our bifunctional NiCo electrode (used on both sides) and commercial Zirfon separator at 0.5 A/cm2 and 40 deg C in 30 wt% KOH showed a cell-level voltage drift of 21 uV/hr. ΔV before/after LSV: 30 mV at the operating point.
Because the same coated NiCo electrode is on the anode and cathode, the 1000-hour cell drift reflects the combined behavior of both half-reactions.
How OER plays in renewable-coupled operation
Dynamic current schedules sometimes accelerate degradation of OER catalysts. Our bifunctional NiCo electrode was tested under 9 days of PV-derived cycling and 100 hours of wind-derived cycling, both in the AEM cell with commercial Zirfon. After 100 hours of wind cycling, ΔV at 0.5 A/cm2 was 20 mV.
Half-cell measurement details
A typical OER half-cell measurement uses a three-electrode setup with a reference electrode (Hg/HgO or saturated calomel) in the same KOH electrolyte. At 100 mA/cm2 in 30 wt% KOH and no IR correction, our bifunctional NiCo electrode measures 260 mV. The published value is the reference point any third-party measurement on the same electrode product can compare against.
Where this specification matters
Industrial applications where oer overpotential 260 mv at 100 ma/cm2 is a primary qualification metric.
Frequently asked questions
What is the OER overpotential of this electrode?
260 mV at 100 mA/cm² in 30 wt% KOH, measured without IR correction. The same coated NiCo electrode used for HER also serves as the OER anode.
How is oer overpotential 260 mv at 100 ma/cm2 measured?
All published values were measured in a 5 cm² AEM cell with our bifunctional NiCo electrode on both sides, 30 wt% KOH electrolyte, zero-gap assembly, and a commercial Zirfon separator (500 µm) as the membrane reference. Overpotentials are reported without IR correction.
Can I reproduce this number on my own cell?
Yes. Bench-scale 5 cm² coupons matching the size used in our published AEM test cell are available. Reproducing the cell conditions (30 wt% KOH, zero-gap, commercial Zirfon separator, bifunctional NiCo electrode on both sides) lets a customer team confirm the published number directly.
What substrate sizes can I order?
We produce the bifunctional NiCo electrode on Ni foam in the 100 to 1000 cm² size range. Bench-scale coupons and pilot-scale electrodes both ship from this same product line. Specific sizes can be discussed for OEM stack integration.
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