An interdisciplinary team has created a revolutionary technology that tackles major challenges in producing clean hydrogen using microwaves. They have also clarified the mechanisms behind this novel process.
Led by Professor Gunsu S. Yun and including doctoral candidate Jaemin Yoo (from the Department of Physics, Division of Advanced Nuclear Engineering), Professor Hyungyu Jin, and doctoral candidate Dongkyu Lee (from the Department of Mechanical Engineering), this POSTECH research team has introduced a transformational technology that overcomes significant obstacles in microwave-assisted clean hydrogen production. Their work, featured as the Inside Front Cover in the Journal of Materials Chemistry A, represents a significant advancement in the quest for sustainable energy.
As society moves away from fossil fuels, clean hydrogen is gaining recognition as a top choice for future energy solutions due to its zero carbon emissions. Nevertheless, current methods of hydrogen production face substantial hurdles. Traditional thermochemical methods, which depend on the oxidation-reduction of metal oxides, demand extremely high temperatures—up to 1,500°C. These processes are energy-intensive, costly, and difficult to scale, posing practical limitations.
To tackle these issues, the POSTECH researchers explored a familiar yet often overlooked energy source: microwave energy1, which is the same energy used in microwave ovens. While microwaves are usually linked to cooking, they can also effectively stimulate chemical reactions. The team showed that microwave energy could reduce the necessary temperature for the reduction of Gd-doped ceria (CeO2), a key material for hydrogen production, to under 600°C, representing a reduction of more than 60 percent in temperature requirements. Surprisingly, microwave energy was able to substitute 75 percent of the thermal energy needed for the reaction, marking a significant milestone for sustainable hydrogen creation.
Another significant breakthrough was the development of “oxygen vacancies”2, which are structural defects that are crucial for splitting water into hydrogen. Traditional methods typically take hours at very high temperatures to create these vacancies, yet the POSTECH team achieved similar results in mere minutes and at temperatures below 600°C by utilizing microwave technology. This fast process was further confirmed through a thermodynamic model that shed light on the mechanisms behind the microwave-driven reaction.
Professor Hyungyu Jin noted, “This study could transform the commercial feasibility of thermochemical methods for producing hydrogen. It will also facilitate the creation of new materials tailored for chemical processes driven by microwaves.” Professor Gunsu Yun commented, “Unveiling a new mechanism powered by microwaves and overcoming the constraints of current processes represent major milestones, achieved through the strong collaborative efforts of our interdisciplinary team.”
This research received support from the Circle Foundation’s Innovative Science and Technology Program, the Ministry of Science and ICT’s Mid-Career Researcher Program, as well as POSTECH’s Basic Science Research Institute, and the Ministry of Trade, Industry, and Energy.
Notes:
1. Microwaves
Microwaves are electromagnetic waves with frequencies between 300 MHz and 300 GHz. These waves are often used to convey energy or heat materials in applications like wireless communication, radar, and cooking in microwave ovens.
2. Oxygen vacancy
This term refers to a condition where an oxygen atom is absent from a material, creating an empty site. This vacancy can significantly enhance electron movement or chemical reactivity.
