Researchers develop solar hydrogen production system

Through the application of a technology, it is now possible to create valuable molecules from tree dregs and then use the electrons gained from this process to create “solar hydrogen.”

It is seen as a potential commercial “green hydrogen” technology since it can manufacture hydrogen using solar power while also improving production efficiency.

The research team at UNIST, which is headed by Professors Jeong-ki Ryu, Ji-wook Jang, and Seong-yeon Jang from the Department of Energy and Chemical Engineering, only breaks down lignocellulosic biomass into compounds with a high added value and then uses the electrons that are liberated in this process to produce solar hydrogen. On the fifth, it declared that it had created “water electrolysis technology.”

It is a device that can generate hydrogen using solely solar energy because it doesn’t require external energy and instead employs a perovskite photoelectrode to make use of the recovered electrons.

“Lignin” was primarily a waste product. Due to its complicated structure, it is difficult to break down, and even when treated at high temperatures and pressures above 150°C, the economic efficiency is low. However, as lignocellulosic biomass makes up 20–30% of the total lignocellulosic biomass, efforts to turn it into a valuable substance have persisted.

With the use of a catalyst called “phosphomolybdic acid (PMA),” Professor Ryu’s team was able to extract just lignin from lignocellulosic biomass. At a low temperature (60°C), PMA was used to react with lignocellulosic biomass to create the valuable component known as “vanillin,” from which only lignin was separated. After that, electrons from the lignin to vanillin conversion process were taken out and used in water electrolysis.

The potential of explosion owing to oxygen produced with hydrogen was one issue with the water electrolysis process that was currently used to obtain hydrogen. The “solar hydrogen production system,” which turns solar energy into fuel, is another water electrolysis technology that demands significant energy, necessitating the addition of electric electricity.

By harnessing electrons obtained during the separation of lignin, Professor Ryu’s team created a new water electrolysis device that reduces the production of oxygen. The application of a perovskite photoelectrode, which absorbs light over the full visible spectrum, increased the efficiency of hydrogen production.

The test results showed that this device can manufacture hydrogen reliably and efficiently for 20 hours while being run in direct sunshine. In order to make hydrogen, the device absorbs a wide range of sunlight; no oxygen or carbon dioxide are produced.

The findings of this study were published on October 3 in Nature Communications. It was funded by the National Research Foundation’s “Nano and Material Technology Development Project-Future Technology Lab” and “Original Technology Development Project-Carbon-neutral Technology Development.”