Scientists have developed an innovative technology to produce hydrogen using sugarcane waste and sunlight.
On Wednesday, researchers from the Ulsan National Institute of Science and Technology (UNIST) announced a breakthrough in hydrogen production. A team led by Professors Jang Ji-Wook and Seo Kwanyong from the Department of Energy and Chemical Engineering, in collaboration with Professor Cho Seungho from the Department of Materials Science and Engineering, has successfully created a method to generate hydrogen from biomass derived from sugarcane waste and silicon photoelectrodes.
The research team developed a photoelectrochemical system that produces hydrogen without carbon dioxide emissions by utilizing furfural obtained from sugarcane waste. This groundbreaking technology generates hydrogen using only sunlight, eliminating the need for external power sources.
During the process, furfural oxidizes on the copper electrode, releasing hydrogen while transforming the remaining material into furoic acid, a high-value substance. Hydrogen is produced at both electrodes, with water also decomposing at the silicon photoelectrode to generate additional hydrogen.
This dual production method theoretically doubles the production speed compared to a conventional photoelectrochemical system. In practice, the system achieved a remarkable production rate of 1.4 mmol/cm²·h, nearly quadrupling the commercialization standard of 0.36 mmol/cm²·h set by the U.S. Department of Energy (DOE).
The hydrogen production in this system begins when the photoelectrode absorbs sunlight and generates electrons. While crystalline silicon photoelectrodes can produce a large number of electrons, which is advantageous for hydrogen production, the generated voltage alone is typically too low to initiate hydrogen production reactions without an external power source.
To address this challenge, the research team induced the oxidation reaction of furfural on the opposite side, effectively balancing the system’s voltage.
This innovative approach maintains the high photocurrent density characteristic of crystalline silicon photoelectrodes while reducing the overall system’s voltage requirements, enabling hydrogen production without external power.
Photocurrent density, which directly correlates with the rate of hydrogen production, measures the flow of electrons per unit area.
The system also incorporates a interdigated back contact (IBC) structure to minimize voltage loss within the photoelectrode. Long-term stability is ensured by encasing the photoelectrode in nickel foil and a glass layer, protecting it from the electrolyte.
The study confirmed that submerging the silicon photoelectrode in water provides a self-cooling effect, enhancing efficiency and stability compared to external coupling structures.
External coupling structures, in contrast, separate the cell that generates electricity to decompose water from the electrolyzer that produces hydrogen.
The research team included co-first authors Ko Myohwa, Lee Myung Hyun, Kim Tae Hyun, Jin Wonjoo, and Jang Won-Sik, all researchers at UNIST.
This groundbreaking study was published in the prestigious international journal Nature Communications, on March 19.