ELECTRODE SPECIFICATION
BIFUNCTIONALSame Electrode on Both Sides
The same coated NiCo electrode operates as both HER cathode and OER anode. Measured at 100 mA/cm2 in 30 wt% KOH without any IR correction: 80 mV HER overpotential and 260 mV OER overpotential.
BIFUNCTIONAL
TESTBEDThis spec
BIFUNCTIONAL
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 bifunctional means in an electrolyzer
A conventional alkaline electrolyzer uses two different electrode formulations: one optimized for the hydrogen evolution reaction (HER) on the cathode side, and a different one optimized for the oxygen evolution reaction (OER) on the anode side. This forces a stack designer to source, qualify, store, and integrate two distinct catalyst products on the two halves of every cell.
Our electrode is bifunctional: the same coated NiCo layer on Ni foam was used on both the cathode and the anode of the published 5 cm2 AEM test cell. In 30 wt% KOH at 100 mA/cm2 and no IR correction, the same electrode delivers an HER overpotential of 80 mV and an OER overpotential of 260 mV.
- Active layer: bi-metallic NiCo, electroless-deposited on Ni foam
- Tested on both cathode and anode in the AEM cell
- HER overpotential: 80 mV at 100 mA/cm2 (no IR correction)
- OER overpotential: 260 mV at 100 mA/cm2 (no IR correction)
- Electrolyte: 30 wt% KOH
0.5 A/cm2 @ 60 deg C
0.5 A/cm2 @ RT
1.0 A/cm2 @ 60 deg C
Cell-level performance with bifunctional NiCo on both sides
In a zero-gap 5 cm2 AEM test cell with our bifunctional NiCo electrode on both sides and a commercial Zirfon separator (500 um), the cell reaches 0.5 A/cm2 at 1.81 V at room temperature (82% energy efficiency) and 1.62 V at 60 deg C (91.4% energy efficiency).
At 1.0 A/cm2, the same bifunctional NiCo electrode with the commercial Zirfon separator measured 2.05 V at room temperature and 1.79 V at 60 deg C. The fact that one electrode formulation can carry both half-reactions across this range simplifies the cell design.
Stability of the bifunctional architecture under steady load
The bifunctional NiCo electrode was operated continuously for 1000 hours at 0.5 A/cm2 and 40 deg C in 30 wt% KOH in an AEM cell with a commercial Zirfon separator (500 um). The cell voltage drifted by 21 uV/hr over the full window. Before/after linear-sweep polarization curves differ by 30 mV at the 0.5 A/cm2 operating point.
The bifunctional electrode held its role on both cathode and anode across the 1000 hours without separate qualification of two distinct electrode SKUs.
Stability under dynamic loads
Solar-irradiance data converted into a current-density schedule was applied to the same bifunctional NiCo electrode and commercial Zirfon separator for 9 continuous days. No major changes were observed after 9 cycles. Wind-speed variation data converted into a current-density schedule was applied for 100 hours. The linear-sweep curve recorded before the wind run and the curve recorded after differ by 20 mV at 0.5 A/cm2.
A bifunctional electrode in a renewable-coupled stack means a single qualification artifact serves both sides of the cell across dynamic operating profiles.
- 9 continuous days of solar-derived cycling (peaks ~570 mA/cm2)
- 100 hours of wind-derived cycling (0 to 0.78 A/cm2)
- DeltaV after wind cycling: 20 mV at 0.5 A/cm2
Practical implications for stack OEMs
A bifunctional electrode reduces the number of distinct electrode SKUs in a stack from two to one. Logistics, inventory, qualification, and replacement-parts management are all simplified. Whether the bifunctional approach is the right fit for a given stack design depends on cell architecture and operating-point requirements, and is typically established during qualification testing on the OEM's own cell.
Where this specification matters
Industrial applications where bifunctional her/oer architecture is a primary qualification metric.
Frequently asked questions
What is the HER overpotential of this electrode?
80 mV at 100 mA/cm² in 30 wt% KOH, measured without IR correction. This is the published reference value for our bifunctional NiCo electrode.
How is bifunctional her/oer architecture 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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