Faradaic efficiency benchmarks: platinum vs. RuO₂‑coated nickel

1. Bench setup

All runs executed on an Autolab PGSTAT302N potentiostat in a three‑electrode cell, Hg/HgO reference, 30 wt % KOH, 80 °C, 10 mA cm⁻² constant‑current chronopotentiometry, 2,000 h continuous. Substrate configurations: (a) polished platinum wire, 0.025 mm; (b) commercial Ni 99.5 % mesh, 400 count; (c) NP1 99.99 % mesh, 400 count; (d) RuO₂‑coated NP1 mesh, 400 count, 2 µm coating.

2. Results

Fig. 1 — Faradaic efficiency, 10 mA cm⁻², 30 wt % KOH, 80 °C, 2,000 h mean.

Overpotential at 10 mA cm⁻² dropped from 312 mV (reference Ni 99.5 %) to 214 mV (RuO₂/NP1), a 98 mV improvement. Durability loss of RuO₂/NP1 at 2,000 h was 0.7 % (absolute), within the reproducibility band of the bench.

3. Discussion

The 94.3 %→96.1 % gap between RuO₂/NP1 and platinum is real but not decisive at stack economics. Platinum raw‑material cost per square metre of active area runs USD 9,800 (spot, April 2025); RuO₂/NP1 runs USD 184. At a 100 GW European build‑out target, the delta compounds to > USD 60 bn in stack‑cost savings without penalty on Levelized Cost of Hydrogen (LCOH).

Validation: Prof. Upadrasta Ramamurty (NTU Singapore) thermal‑cycling and electrolyser‑substrate bench 2025, cross‑referenced with independent IIT Delhi bench. Literature index: /api/citations.json.