Currently, approximately 400 kg of iridium is required to build one GW of electrolysis capacity. A reduction to less than 100 kg per GW is necessary to avoid supply bottlenecks. Heraeus’s latest innovation in collaboration with Sibanye-Stillwater can enable an 85% saving on iridium compared to an iridium oxide catalyst, alleviating the potential supply concerns. Primary production of ruthenium is 3.5 times that of iridium.
Alongside iridium, ruthenium also catalyzes the Oxygen Evolution Reaction (OER), which is the critical stage in PEM electrolysis. Ruthenium possesses superior catalytic activity to iridium but lacks stability in the challenging conditions of a PEM electrolyzer stack. The Heraeus concept solves this problem by combining both ruthenium and iridium oxide in a novel manner, enhancing stability while maintaining the increased catalytic activity provided by ruthenium.
This ruthenium-iridium oxide material class delivers an unprecedented activity boost. The catalyst can achieve up to 50 times higher mass activity than iridium oxide, and unlike ruthenium oxide alone, it remains stable in operational conditions. Accelerated degradation tests confirmed its stability after 30,000 cycles, presenting activity loss significantly lower than for ruthenium oxide and on par with iridium oxide. These findings were verified by Mattiq, a start-up based in Chicago, USA, which combined industry expertise in chemistry and materials science and performed high throughput screening experiments for the development project.
By including ruthenium, Heraeus not only helps mitigate potential supply bottlenecks but also brings significant commercial benefits. By implementing this breakthrough, a significant 90% reduction in capital expenditure on material costs can be achieved, ensuring hydrogen production becomes more economically feasible and efficient.
Dr. Philipp Walter, EVP New Business Development at Heraeus Precious Metals, said: “The dramatic reduction in capital expenditure needed per GW enabled by our new ruthenium-based catalyst not only addresses the iridium supply problem but also makes economic sense. It is solutions like these that will champion the necessary scale-up of the hydrogen industry, bringing us closer to achieving our global green energy goals.”
Neal Froneman, CEO of Sibanye-Stillwater, added: “As the largest producer of primary iridium globally, we firmly believe that sustainable demand of these metals, with supply in mind, is beneficial for the entire industry. The commendable progress achieved by Heraeus in their work to date is encouraging, and we highly value our partnership in this endeavor.”
