Scientists have designed ultra-thin materials that mimic LEGO bricks—only these build the future of green energy. A breakthrough Janus heterobilayer could revolutionize solar-powered hydrogen production with record-breaking efficiency.
Key Points at a Glance
- A new 2D material—WS₂-SMoSe Janus heterobilayer—achieves 16.62% solar-to-hydrogen efficiency.
- These materials enhance photocatalysis through intrinsic electric fields and improved charge separation.
- Janus heterobilayers are engineered by combining different atomic layers like LEGO bricks.
- Study offers a blueprint for discovering high-performance materials for sustainable hydrogen production.
- The research was published in ACS Applied Energy Materials.
Hydrogen has long been hailed as the fuel of the future. Clean, abundant, and energy-dense, it has the potential to replace fossil fuels and reshape how we power everything from homes to cars. The challenge, however, lies in producing it sustainably and efficiently. Now, researchers at Tohoku University in Japan and Vietnam National University in Ho Chi Minh City (VNU-HCM) may have found a vital piece of the puzzle—an atomically thin, ultra-efficient material that could supercharge solar-driven hydrogen production.
Their innovation centers on a class of materials called Janus heterobilayers, named after the two-faced Roman god. These unique structures are made by stacking two different two-dimensional materials, with asymmetry on either side that creates internal electric fields. These fields are key—they enhance the separation of the electrons and holes generated by sunlight, a crucial step for making photocatalytic water splitting viable on a large scale.
Among the 20 different material combinations the team studied, one stood out: the WS₂-SMoSe Janus heterobilayer. This nanoscale structure achieved a solar-to-hydrogen conversion efficiency of 16.62%, outperforming many existing materials that typically fall below 15%. It’s a meaningful leap forward in the quest to produce green hydrogen from sunlight and water alone.
The research was led by Nguyen Tuan Hung, assistant professor at the Frontier Research Institute for Interdisciplinary Science (FRIS) at Tohoku University, and Vu Thi Hanh Thu, associate professor at VNU-HCM. Their work, published in ACS Applied Energy Materials, offers a data-driven strategy for designing next-generation photocatalysts. By experimenting with atomic arrangements the way a child might with LEGO bricks, the team created a systematic approach to identifying optimal combinations for solar-powered hydrogen generation.
First author Nguyen Tran Gia Bao likens the research process to playing with interlocking blocks: “Combining TMDCs with Janus layers is akin to building with LEGO—there are almost countless configurations to try. Our methodology allows us to efficiently and precisely identify the most promising material combinations.”
These findings do more than just set a new benchmark in photocatalytic performance—they provide a design principle for future exploration. Janus heterobilayers consist of two-dimensional transition-metal dichalcogenides (TMDCs) with one side of the layer featuring a different chalcogenide element than the other. This deliberate asymmetry results in an intrinsic dipole and electric field, effectively giving the material built-in electronic directionality. This feature dramatically reduces energy loss from electron-hole recombination, one of the key limitations in conventional photocatalysts.
By exploiting this internal electric potential, these materials not only improve efficiency but also simplify the overall system. Unlike many current water-splitting setups that require complicated and costly infrastructure, Janus heterobilayers could pave the way for smaller, cheaper, and more scalable hydrogen production units.
“This is a new way of thinking about solar hydrogen,” says Nguyen Tuan Hung. “We now have a clearer idea of what properties we’re looking for—and how to find them faster.”
The implications of this discovery are substantial. As nations strive to meet climate targets and phase out carbon-heavy energy sources, innovations like these will be central to building a resilient, low-emission energy infrastructure. Green hydrogen, in particular, is seen as a cornerstone of decarbonization strategies in transportation, industry, and power generation.
While this research is still at a theoretical and computational stage, the team is optimistic about the path forward. They plan to explore other Janus-TMDC combinations, pushing further toward even more efficient materials. With the right breakthroughs, solar hydrogen could go from a lab-scale concept to an everyday energy solution—one molecular layer at a time.
Source: Tohoku University
