Iridium
IRIDIUM OXIDE CATALYST
P-TECH 0400
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 using a high surface area, electrochemically active, and stable anodic electrocatalyst.
The iridium oxide 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 and is stable under strong oxidation conditions.
Pure iridium oxide catalysts should be used in situations where ruthenium can cause detrimental effects for the performance of the electrolyser or when ultra-pure oxygen is required.
CATALYST SPECIFICATION
| Appearance | Black Powder |
| Molecular Formula | IrO2 |
| BET Surface Area | 102 - 104 m² g⁻¹ |
| EDX (by atomic mass) | 35.4 % Ir |
| Crystalline Size | 4.3mm |
| Purity | >98% |
CATALYST PERFORMANCE
The catalyst powder retains its high activity at both high and low current densities, and a range of temperatures. The cyclic voltammetry below is taken before and after 2000 voltage cycles (held for 30s at each voltage).
Durability tests were performed in an electrolyser cell at 1A ∙ cm⁻² on Nafion® N117 alongside TFP Hydrogen’s Pt/C cathode catalyst (60˚C). The results shown in figure 4 show a degradation rate below 4 μV ∙ hr⁻¹ (multiple tests).
FIGURE 1
SEM image of the iridium oxide showing the high surface area powder.
FIGURE 2
Electrolyser data utilising TFP Hydrogen's iridium oxide catalyst on the anode and TFP Hydrogen's platinum/carbon on the cathode.