Iron-based catalyst helps zinc-air batteries power devices without precious metals

Researchers at Tohoku University have developed an iron-based catalyst that improves the performance of zinc-air batteries, a technology viewed as a lower-cost alternative to lithium-ion systems for energy storage.
The team focused on overcoming a key limitation of the oxygen reduction reaction (ORR) in zinc-air batteries. While zinc-air batteries draw oxygen from the surrounding air instead of storing it internally, the ORR process is relatively slow, restricting overall battery performance.
To address the problem, the researchers engineered a heterointerface combining iron oxide (Fe2O3) and samarium oxide (Sm2O3). The interface altered how electrons behave at the catalyst surface, helping speed up reaction kinetics and improve battery efficiency.
According to the researchers, the catalyst weakens excessive bonding between iron sites and hydroxyl intermediates, allowing the reaction to proceed more smoothly and reducing one of the major bottlenecks in zinc-air battery operation.
Reworking battery chemistry
Fe2O3 was selected because it is abundant, inexpensive and stable under the alkaline conditions commonly found in zinc-air batteries. However, iron-based catalysts typically suffer from strong Fe-OH interactions that slow the release of reaction products.
The newly developed Fe2O3/Sm2O3 interface was designed to overcome that limitation. Researchers said charge redistribution, orbital hybridization and spin modulation at the interface helped optimize the catalyst’s behavior during oxygen reduction.
As a result, the catalyst delivered faster ORR kinetics and improved durability compared with conventional approaches. The work also avoided the use of expensive noble metals, which are commonly used in high-performance catalysts.
The team evaluated the material in both liquid and flexible all-solid-state zinc-air batteries. Beyond laboratory measurements, the researchers demonstrated practical operation by powering a small LED lamp and charging a smartphone.
“The catalyst achieves high ORR activity, improved reaction kinetics, excellent durability, and superior performance in both liquid and flexible all-solid-state zinc-air batteries,” said Hao Li, distinguished professor at the Advanced Institute for Materials Research (WPI-AIMR).
Beyond precious metals
Zinc-air batteries have attracted attention because they use widely available materials and can theoretically deliver high energy density. Unlike lithium-ion batteries, they rely on oxygen from the atmosphere as part of the electrochemical process.
Researchers believe improving catalyst performance could help make the technology more practical for real-world applications, including portable electronics, wearable devices, and large-scale energy storage systems.
“For the general public, this means that we may be closer to affordable and sustainable clean-energy technologies,” Li said.
The researchers say the study demonstrates a potential pathway toward lower-cost energy storage by replacing precious-metal catalysts with more abundant materials while maintaining strong electrochemical performance.
Future work will focus on expanding the interfacial spin-regulation strategy used in the study and exploring whether similar approaches can improve other energy-conversion and storage technologies.
The findings were published in Angewandte Chemie International Edition.