A domestic research team has developed an artificial leaf that produces hydrogen under indoor lighting. A path has opened to harvest clean hydrogen by recycling electricity used for lighting, which accounts for 19% of global power consumption.
On the 19th, a research team led by Jang Ji-hyeon, a professor in the Department of Energy and Chemical Engineering at Ulsan National Institute of Science and Technology (UNIST), said it developed an artificial leaf that produces hydrogen under light-emitting diode (LED) lighting by combining an efficient photoelectrode with a hydrogen production catalyst.
A photoelectrode is a material that receives light and generates charge carriers, like chlorophyll in plants. The photoelectrode developed by the team is made of a sulfide material that efficiently absorbs indoor lighting, which is dimmer than sunlight, to generate charge carriers. The generated charge carriers pass through a titanium dioxide layer to the hydrogen production catalyst layer on the back, and on the three-dimensional nickel surface that serves as the hydrogen production catalyst layer, the charge carriers react with water to produce hydrogen.
In particular, sulfides undergo photo-corrosion when exposed to strong light, but weak indoor lighting can minimize this. However, to compensate for the reduced number of charge carriers due to weak light, the researchers designed an electrode structure in which titanium dioxide is junctioned to the sulfide. This junction structure prevents positive and negative charge carriers from recombining and disappearing, ensuring that the limited charges are used fully for hydrogen production without recombination losses. In addition, by coating the sulfide surface with phosphate to block photo-corrosion of the sulfide and increase charge transport speed, the team achieved both durability and efficiency.
The developed artificial leaf recorded the same photocurrent as when using an expensive platinum catalyst with indoor lighting alone, without applying an external voltage, and maintained 94% of its initial performance after 12 hours. Photocurrent is an indicator that can gauge the hydrogen production of an artificial leaf.
In addition, the three-dimensional nickel used as the hydrogen production catalyst is inexpensive and can be printed like ink, making it easy to fabricate to the sizes needed for commercialization. The researchers also produced a large module by connecting four 85 ㎠ artificial leaves in series, and this module recorded a total photocurrent of 5 mA (milliamperes) under indoor lighting.
Professor Jang Ji-hyeon said, "Unlike sunlight, which is sensitive to weather, indoor lighting has the advantage of being steady," and noted, "As this study confirms that light previously wasted indoors can be used as an energy source for hydrogen production, we plan to supplement hydrogen separation and recovery technologies going forward."
The results of this study were published online on Jan. 16 (local time) in the international journal "Applied Catalysis B: Environmental and Energy."
References
Applied Catalysis B: Environmental and Energy (2026), DOI: https://doi.org/10.1016/j.apcatb.2026.126449