Scientists have created innovative energy technology to generate eco-friendly hydrogen using components found in coffee.
Professor Chiyoung Park from the Department of Energy Science and Engineering at Daegu Gyeongbuk Institute of Science & Technology (DGIST; President Kunwoo Lee) has developed a groundbreaking technique for making supramolecular fluorophore nanocomposites with nanomaterials, establishing a sustainable system for producing solar organic biohydrogen.
In collaboration with Professor Hyojung Cha from the Department of Hydrogen and Renewable Energy at Kyungpook National University, Professor Park utilized the strong nanosurface adsorption characteristics of tannic acid[1]-based metal-polyphenol polymers. This approach allowed for the control of self-assembly and optical features of fluorescent dyes while uncovering the mechanisms of photoexcitation[2] and electron transfer. As a result, he successfully built a solar-driven biohydrogen production system using bacteria that possess hydrogenase enzymes.
In natural photosynthesis, chlorophyll captures light energy and converts it into chemical energy by transferring electrons. Artificial photosynthesis mimics this natural process, utilizing sunlight to create valuable resources like hydrogen and has become a focus as a sustainable energy alternative.
The research team crafted a supramolecular photocatalyst capable of electron transfer similar to natural chlorophyll by altering rhodamine—a common fluorescent dye—into an amphiphilic form. They incorporated metal-polyphenol nano-coating technology based on tannic acid to enhance performance and resilience. Their results showed they could produce around 18.4 mmol of hydrogen per hour per gram of catalyst under visible light, which is 5.6 times more effective than prior studies using the same phosphor.
The team also integrated their newly developed supramolecular dye with Shewanella oneidensis MR-1[3]—a bacterium known for its electron transfer abilities—to create a bio-composite system that uses sunlight to convert ascorbic acid (vitamin C) into hydrogen. This system showed stable operation over an extended period and continuous hydrogen production.
Professor Park noted, “This research is a significant milestone revealing the detailed mechanisms of organic dyes and artificial photosynthesis. I aim to pursue further studies involving new supramolecular chemistry-based systems paired with functional microorganisms and novel materials.”
This research received support from the Basic Research Laboratory Project and the Mid-Career Researcher Support Project from the National Research Foundation of Korea, as well as the Alchemist Project funded by the Ministry of Trade, Industry, and Energy. The findings (with Seokhyung Bu, a PhD student, as the first author) were published in Angewandte Chemie International Edition.
[1] Tannic acid: An environmentally friendly substance easily sourced from coffee and tea, which can be coated at the nanoscale through a simple method. It has wide-ranging uses, including photocatalysis and pollutant removal.
[2] Photoexcitation: This term describes the process where electrons in a material are elevated to a higher energy level via light energy (photons).
[3] Shewanella oneidensis MR-1: This bacterium is renowned for its ability to decompose metals and minerals naturally. It plays a key role in eco-friendly energy research, particularly for hydrogen production.
