Iridium Ruthenium
IRIDIUM RUTHENIUM OXIDE CATALYST
P-TECH 0401
BACKGROUND
Hydrogen produced by proton exchange membrane (PEM) electrolysis technology is purer than any other form of hydrogen production. In order to compete with alternative forms of hydrogen production, a high efficiency electrolyser is required.
The electrochemical energy losses in a PEM electrolyser are primarily due to the large overpotential at the oxygen evolution anode. These losses can be minimised through the use of a high surface area, electrochemically active, and stable anodic electrocatalyst.
IrO₂ and RuO₂ are well established as anodic catalysts prepared by thermal decomposition of metal precursors onto titanium substrates. This method is unsuitable for PEM electrolysers due to the difficulty in obtaining intimate contact between the electrocatalyst and the ionically conductive membrane.
The iridium ruthenium nano-crystalline powder produced by TFP Hydrogen Products can be applied to the membrane as an ink. It has a low overpotential for the oxygen evolution reaction compared to standard IrO₂ and is stable under strong oxidation conditions.
Key to the catalyst longevity is the formation of an iridium-ruthenium solid solution.
CATALYST SPECIFICATION
| Appearance | Black Powder |
| Molecular Formula | Ir |
| BET Surface Area | 119 - 132 m² g⁻¹ |
| EDX (by atomic mass) |
9.0 % Ru 22.6 % Ir |
| XRF (by weight) |
14.7 % RuO₂ 68.3 % IrO₂ |
| Crystalline Size | 6 nm |
| Purity | >98% |
CATALYST PERFORMANCE
The catalyst powder retains its high activity at both high and low current densities, and a range of temperatures.
When placed in an electrolyser cell the catalyst outperforms traditional iridium oxide electrocatalysts. The results in Figure 2 show performance in a single electrolyser run at 60˚C (Nafion® N212 membrane).
FIGURE 1
SEM image of the Ir Ru oxide showing high surface area & range of pore size.
FIGURE 2
Electrolyser voltage utilising TFP Hydrogen’s Ir Ru oxide on the anode and platinum on the cathode