Amorphous Ruthenium Oxide (RuOx) Coated Electrode for Electrolyzer, CECEARuO

Ruthenium Oxide (RuOx) coated metal Felt (or carbon paper) is the "gold standard" anode for Proton Exchange Membrane (PEM) water electrolyzers. Unlike alkaline systems that can use nickel, PEM systems operate at a very low pH (acidic) and high potentials, where almost all other metals—except titanium and noble metals—would rapidly corrode.

In PEM systems, the environment is highly acidic (pH < 2). Most transition metals (like the FeCoNi we discussed earlier) would dissolve instantly. (1) The RuOx Advantage: It has the lowest overpotential of any catalyst in acid, meaning it requires the least amount of electricity to split water. (2) The Stability Trade-off: Pure RuOx is unstable at the high potentials (> 1.45 V) required for water splitting. It tends to oxidize into RuO4, which is volatile and soluble, leading to "catalyst leaching". (3) Industrial Solution: Most commercial PEM anodes use a Mixed Metal Oxide (MMO) coating, blending RuO2 with IrO2. The Iridium acts as a "sacrificial" or stabilizing agent to protect the Ruthenium.

In alkaline systems (20–30% KOH), RuOx is technically superior in performance but rarely used. (1) Economics: Since Ni-Fe based catalysts (like FeCoNi) can achieve very high efficiency in alkaline media for a fraction of the cost, RuOx is usually deemed "over-engineered" for standard AWE. (2) Application: It is only used in specialized alkaline cells where extremely high current densities or specific ultrapure hydrogen requirements justify the cost of noble metals.

Notes: Please try to store the RuOx electrodes in a dry place.

References: 

1. R. Boppella, et al. Strongly Coupled Metal/Amorphous Ru/RuOx Heterostructure for Efficient Electrocatalytic Hydrogen Production, ACS Catal. 2025, 15, 19, 16981–16991.
2. M. Guo, et al. Sacrificial Doping of Interstitial Lithium Facilitated Undoped Amorphous/Crystalline RuO2 Toward Boosted Acidic Water Oxidation, Adv. Energy Meter., 2025, 15, e03199.