Abstract

Dye-sensitized photoelectrochemical cells hold promise for artificial photosynthesis but face challenges such as low photocurrents and limited stability. To address these limitations, a cascade-type dye-sensitized photoelectrode is developed by encapsulating a dye-sensitized TiO2 layer and redox mediator within platinum-sputtered nickel foil. This buried-junction design enables spatially controlled cascade charge transfer, featuring effective photoconversion and Ni-catalyzed water oxidation, while suppressing undesirable recombination current leakage. Through a comprehensive study involving the selection of redox mediators and water oxidation catalysts, the best-performing photoelectrode for water splitting achieves a photocurrent of 14.0 mA cm−2 at 0.72 V vs. reversible hydrogen electrode (RHE), a Faradaic efficiency of 98%, and photostability of 30 hours. Moreover, the versatility of our design extends to bias-free H2O2 production, achieving a photocurrent density of 7.83 mA cm−2, a Faradaic efficiency of 92.2%, and a record-high solar-to-fuel efficiency of 4.15% (2.13 µmol min−1 cm−2), with photostability of 150 hours.

A research team at UNIST has introduced an innovative dye-sensitized electrode that marks a significant leap in artificial photosynthesis technology. Demonstrating exceptional efficiency and durability, the system can produce hydrogen peroxide solely using sunlight—bringing us closer to sustainable chemical manufacturing.

Led by Professor Tae-Hyuk Kwon from the Department of Chemistry and Professor Ji-Wook Jang from the School of Energy and Chemical Engineering, the team developed an electrode that mimics natural electron-transfer processes in plants. The device features an organic dye layer combined with a redox mediator, encapsulated within a nickel foil structure. This configuration facilitates a cascade-like, stepwise electron transfer—from the dye to the mediator, then to the nickel substrate, and ultimately to the catalyst—minimizing charge loss and enhancing stability.

Unlike conventional designs with dyes exposed directly to electrolytes, this architecture prevents degradation and significantly prolongs operational lifespan. The electrode achieved a Faradaic efficiency of 98% in water splitting and demonstrated stable performance over 150 hours. When used for sunlight-driven hydrogen peroxide production, it attained a solar-to-fuel efficiency of 4.15%, setting a new global record without requiring external voltage.

“By optimizing the electrode interface, we were able to enhance efficiency and durability simultaneously,” explained Professor Kwon. “This environmentally friendly system paves the way for sustainable production of valuable chemicals using solar energy.”

According to the research team, this breakthrough addresses core challenges in artificial photosynthesis—namely, efficiency, stability, and environmental safety—paving the path toward scalable, renewable fuel and chemical production. Its simplicity and eco-friendly design hold great promise for future applications in green chemistry and renewable energy.

This research was participated by researchers Jun-Hyeok Park, Kyounglim Kim, and Jinyoung Lee as the first co-authors. The findings of this research have been published in Advanced Functional Materials on April 13, 2026.

Journal Reference

Jun-Hyeok Park, Kyounglim Kim, Jinyoung Lee, et al., "Bias-Free Highly Efficient and Stable Dye-Sensitized Photoelectrochemical Cells via Cascade Charge Transfer," Adv. Funct. Mater., (2026).