A team of scientists from Korea and Japan has discovered a new type of crystal that can “breathe” — releasing and absorbing oxygen repeatedly at relatively low temperatures. This unique ability could transform the way we develop clean energy technologies, including fuel cells, energy-saving windows, and smart thermal devices.
The newly developed material is a special kind of metal oxide made of strontium, iron, and cobalt. What makes it extraordinary is that it can release oxygen when heated in a simple gas environment and then take it back in, all without falling apart. This process can be repeated many times, making it ideal for real-world applications.
This remarkable study has been led by Professor Hyoungjeen Jeen from the Department of Physics, Pusan National University, Korea, and co-authored by Professor Hiromichi Ohta from the Research Institute for Electronic Science, Hokkaido University, Japan. Their findings have been published in the journal Nature Communications on August 15, 2025. “It is like giving the crystal lungs and it can inhale and exhale oxygen on command,” says Prof. Jeen. Controlling oxygen in materials is crucial for technologies like solid oxide fuel cells, which produce electricity from hydrogen with minimal emissions. It also plays a role in thermal transistors — devices that can direct heat like electrical switches — and in smart windows that adjust their heat flow depending on the weather.
Until now, most materials that could do this kind of oxygen control were too fragile or operated only at the harsh conditions like extremely high temperatures. This new material works under milder conditions and remains stable. “This finding is striking in two ways: only cobalt ions are reduced, and the process leads to the formation of an entirely new but stable crystal structure,” explains Prof. Jeen. They also showed that the material could return to its original form when oxygen was reintroduced, proving that the process is fully reversible. “This is a major step towards the realization of smart materials that can adjust themselves in real time,” says Prof. Ohta. “The potential applications range from clean energy to electronics and even eco-friendly building materials.”
Funding: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (RS-2025-00558200). Also, this work was partially supported under the framework of international cooperation program managed by the NRF (NRF-2022K2A9A1A01098180). H.O. is supported by Grants-in-Aid for Scientific Research A (22H00253) from the Japan Society for the Promotion of Science (JSPS). Part of this work was supported by the Crossover Alliance to Create the Future with People, Intelligence and Materials, and by the Network Joint Research Center for Materials and Devices. H. J. acknowledges the support of Korea Basic Science Institute (National research Facilities and Equipment Center) grant funded by the Ministry of Education (grant No. RS-2024-00435344). S. P. and S. Y. acknowledge support from the Nano & Material Technology Development Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (RS-2024-00460372).