Bioinspired hydrogels harness sunlight: A step closer to artificial photosynthesis

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Mimicking how plants convert sunlight into energy has long been a dream for scientists aiming to create renewable energy solutions. Artificial photosynthesis is a process that seeks to replicate nature's method, using sunlight to drive chemical reactions that generate clean energy. However, creating synthetic systems that work as organically as natural photosynthesis has been a significant challenge until now.

Now, researchers from the Japan Advanced Institute of Science and Technology (JAIST) and the University of Tokyo have designed a new type of bioinspired hydrogel that can generate hydrogen and oxygen by splitting water molecules using sunlight. Their study was published online in Chemical Communications.

This design can be a potential game changer in the quest for clean energy, as hydrogen is seen as a promising fuel for the future. Moreover, this advancement in hydrogen production could be compared to other clean energy technologies like solar photovoltaics and electrolysis-based hydrogen production.

These methods rely on external energy sources, whereas the hydrogel system mimics nature by using sunlight directly to split water, potentially improving efficiency and reducing costs.

The research team, led by Associate Professor Kosuke Okeyoshi, along with his doctoral student Reina Hagiwara at JAIST, and Professor Ryo Yoshida at the University of Tokyo, designed these hydrogels with carefully structured polymer networks. These networks help control the transfer of electrons, which is crucial for splitting water into hydrogen and oxygen.

The hydrogels are packed with functional molecules, such as ruthenium complexes and platinum nanoparticles, which work together to simulate the natural process of photosynthesis.

"The biggest challenge was figuring out how to arrange these molecules so they could transfer electrons smoothly," says Prof. Okeyoshi. "By using a polymer network, we were able to prevent them from clumping together, which is a common issue in synthetic photosynthesis systems."

Adding further, first-author Reina Hagiwara, a Ph.D. student at JAIST, says, "What's unique here is how the molecules are organized within the hydrogel. By creating a structured environment, we've made the energy conversion process much more efficient."

One of the key breakthroughs in this study is the hydrogels' ability to prevent the functional molecules from aggregating—a major issue in previous artificial photosynthesis systems. As a result, the team was able to significantly boost the activity of the water-splitting process and produce more hydrogen compared to older techniques.

This design has major implications for clean energy. Hydrogen, when produced using just water and sunlight, could become a key player in future energy systems, offering a renewable alternative to fossil fuels.

As Prof. Okeyoshi explains, "Hydrogen is a fantastic energy source because it is clean and renewable. Our hydrogels offer a way to produce hydrogen using sunlight, which could help sustainably reshape energy technologies."

By making artificial photosynthesis more active, this study moves us closer to a future where renewable hydrogen could power industries, transportation, and energy storage systems.

Despite these promising results, the researchers note that there is still work to be done. Scaling up the production of these hydrogels and ensuring their long-term stability will be important next steps.

"We have shown the potential, but now we need to refine the technology for industrial use," says Prof. Okeyoshi. "The possibilities are exciting, and we're eager to continue pushing forward."

The team also plans to explore precise integration in the hydrogels to further enhance their energy conversion efficiency.

More information: Reina Hagiwara et al, Bioinspired hydrogels: polymeric designs towards artificial photosynthesis, Chemical Communications (2024). DOI: 10.1039/D4CC04033C

Journal information: Chemical Communications

Provided by Japan Advanced Institute of Science and Technology