Domestic researchers have developed "artificial leaf" technology that produces hydrogen from water using only indoor LED light. This method generates hydrogen by inducing a photoelectrochemical reaction even in weak lighting environments.

A research team led by Professor Ji-Hyeon Jang of the Department of Energy and Chemical Engineering at UNIST announced on the 19th that they have developed an artificial leaf combining a photoelectrode that operates under indoor lighting conditions with a hydrogen production catalyst. The research results were published online on the 16th of last month in the international journal 'Applied Catalysis B: Environmental and Energy' and are awaiting formal publication.

Conventional photoelectrochemical-based hydrogen production technologies have primarily utilized sunlight. However, indoor lighting has limitations in that it is difficult to secure charge generation and separation efficiency due to low light intensity. To address this issue, the research team designed a structure in which a titanium dioxide (TiO₂) layer is bonded to a sulfide (CdS) photoelectrode. This structure helps utilize limited charges for the hydrogen generation reaction by reducing the recombination of generated positive and negative charges.

In addition, phosphate (Pi) was coated on the surface of the sulfide to suppress photocorrosion caused by strong light and improve the charge transfer speed. The generated charge is transferred to the three-dimensional nickel (3D-Ni) catalyst layer on the back side and reacts with water to produce hydrogen.

Experimental results showed that a photocurrent of 119–120 microamperes (µA/cm²) was measured using only indoor lighting without external voltage. This is similar to the 121 µA/cm² reported when using a platinum (Pt) catalyst. Furthermore, it maintained 94% of its initial performance even after 12 hours of operation. Photocurrent is used as an indicator to gauge the potential for hydrogen production.

The research team explained that they fabricated a module consisting of four 85 cm² artificial leaves connected in series and recorded a total photocurrent of 5 milliamperes (mA) under indoor lighting. It was also confirmed that the 3D nickel catalyst is relatively inexpensive and can be produced through a printing process, demonstrating the potential for large-area expansion.

This research was conducted with support from the 'Chemical Engineering and Bio-Convergence Process Research Center for Microplastic Response' ERC project, the Mid-Career Researcher Project, and the InnoCore Project.