Researchers have unveiled a groundbreaking catalyst for proton exchange membrane water electrolyzers (PEMWEs) embedding iridium (Ir) and manganese oxides (MnOx) within porous nanosheets. This innovation could significantly reduce the reliance on iridium and improve the efficiency of hydrogen production.
The study, conducted by scientists from Peking University and backed by the National Natural Science Foundation of China, addresses the pressing challenge posed by the scarcity and cost of iridium, which has limited the large-scale application of PEMWEs. Current devices typically use over 400 kg of iridium per gigawatt, resulting in high expenditure and sustainability concerns.
To develop this new catalyst, the researchers employed advanced synthesis techniques to form Ir/MnOx structures. These have demonstrated up to 150.6 times higher mass activity compared to commercial iridium dioxide (IrO2), highlighting their potential for enhancing the oxygen evolution reaction (OER), which is integral to efficient hydrogen production.
Notably, the Ir/MnOx catalyst proves effective at just 0.2 mg/cm2 loading and operates at a low cell voltage of 1.63 V to deliver 1 A/cm2 over 300 hours. Such performance places it among the best candidates for low iridium-based PEMWEs.
One of the key findings from this work is the role of abundant Ir-O-Mn bonds at the catalyst interface, which facilitate efficient electron transfer and stabilize active low-valence Ir3+ species. This helps prevent over-oxidation of iridium, addressing one of the major durability challenges associated with traditional catalysts.
According to the authors, "Ir/MnOx demonstrates comparable performance under 10-fold lower Ir loading, taking cell voltage of 1.63 V to deliver 1 A cm-2 for over 300 h, positioning it among elite low Ir-based PEMWEs." This innovative catalyst not only shows promise for operational efficiency but also suggests new pathways for sustainable hydrogen technology.
Future studies are recommended to explore additional enhancements and stability metrics of the Ir/MnOx catalyst across varied operational conditions, reinforcing its viability for real-world applications.