A joint research team from DGIST and Kookmin University has developed a photoelectrode that produces hydrogen from sunlight using a water-based, low-voltage fabrication process, replacing the high-voltage, solvent-heavy methods traditionally used to build such devices. The work, led by Professor Jongmin Choi of DGIST’s Department of Energy Science & Engineering in collaboration with Professor Younghoon Kim of Kookmin University, was published in the journal Small.
Solar hydrogen production technologies commonly rely on titanium dioxide (TiO2), a material prized for its stability but limited by its ability to absorb only ultraviolet light. To widen the absorbed spectrum, researchers have sought to combine TiO2 with silver- and bismuth-based nanomaterials. The obstacle has been in the attachment step: conventional methods require voltages of 200 volts or more and toxic organic solvents to bind these nanomaterials to electrodes, undermining the environmental promise of the technology itself.
The team’s solution centered on the surfaces of the nanocrystals. They replaced the molecules coating the nanocrystals with hydrophilic molecules that mix readily with water, then applied a process called aqueous electrophoretic deposition, in which a low voltage applied in an aqueous solution drives the particles to adhere to the electrode. This eliminated the need for both the high voltages and the organic solvents.
The change in operating conditions was dramatic. The process voltage fell from roughly 200 V to just 4 V, comparable to a household battery, and the electrode coating was completed in about three minutes in a safe aqueous solution. Because the deposition no longer occurred under high-voltage conditions, the researchers also avoided the surface damage and impurity formation, in the form of oxidation byproducts, that plagued earlier methods.
Performance improved as well. The new photoelectrode showed an approximately tenfold or greater increase in photocurrent under illumination compared with conventional single-material electrodes. Under conditions similar to natural sunlight, it achieved a photocurrent density of 3.0 milliamperes per square centimeter.
Durability and gas production were also verified. After two hours of continuous light exposure, the electrode retained 65.1 percent of its initial performance, and gas analysis confirmed that hydrogen was successfully produced during operation.
A further distinction of the work lies in its materials choices. The photoelectrode uses components that completely exclude hazardous substances such as lead and cadmium, while substantially reducing the use of organic solvents and the reliance on high voltages during deposition. According to the team, this combination of safety and performance is what positions the process as a step toward genuinely eco-friendly green hydrogen production.
“The significance of this study lies in achieving high hydrogen production efficiency through a safe and clean water-based, low-voltage process, overcoming the limitations of conventional processes that relied on high voltages and toxic solvents,” said Professor Jongmin Choi. “This achievement will serve as an important foundation for accelerating the practical application of eco-friendly hydrogen production technology.”
The research was supported by the Nano & Material Technology Development Program of the Ministry of Science and ICT and the National Research Foundation of Korea, along with the InnoCORE Program of the Ministry of Science and ICT. Dr. Jin Young Park and Ph.D. student Haejeong Kim of DGIST served as co-first authors on the paper, titled “Eco-Friendly Aqueous Electrophoretic Deposition of TiO2–AgBiS2 Heterojunctions for Photoelectrochemical Hydrogen Production,” published in Small on September 3, 2026.
By cutting the deposition voltage to battery-level levels, shortening fabrication to minutes, removing toxic solvents and heavy metals, and simultaneously raising photocurrent, the study addresses several of the practical barriers that have kept solar hydrogen photoelectrodes tethered to environmentally problematic manufacturing. The researchers present the aqueous electrophoretic deposition route as a foundation for scaling up cleaner production of hydrogen, a clean energy carrier, from sunlight and water.
Subject of Research: Eco-friendly aqueous electrophoretic deposition of TiO2-based photoelectrodes for solar hydrogen production
Article Title: “Eliminating hazardous substances and boosting efficiency tenfold”: DGIST develops eco-friendly solar hydrogen production technology
Article References: “Eliminating hazardous substances and boosting efficiency tenfold”: DGIST develops eco-friendly solar hydrogen production technology. Original publication (Bibliographic details unavailable.)
Image Credits: AI Generated
DOI: Not provided
Keywords: solar hydrogen, photoelectrode, titanium dioxide, nanocrystals, aqueous electrophoretic deposition, green hydrogen, DGIST, Kookmin University, photocurrent, water-based process, AgBiS2, materials science
News Source: Neil Sanderson. (October 30, 2026). Low-Voltage Water-Based Process Makes Solar Hydrogen Photoelectrodes Safer and More Efficient. Scienmag.
