A new photocatalytic platform for the bulk production of hydrogen has been developed by a research group headed by Professor Taeghwan Hyeon at the Center for Nanoparticle Research within the Institute for Basic Science (IBS) in Seoul, South Korea.
The study performed by the group on the photocatalytic platform resulted in the development of a floatable photocatalytic matrix. This enables effective hydrogen evolution reactions with clear benefits over traditional hydrogen production platforms like film or panel types.
In recent times, the significance of alternative energy has risen due to global challenges, such as climate change and environmental pollution. Among the availability of numerous candidates for alternative energy sources, hydrogen energy harvested by photocatalysis is especially emphasized for its sustainable green energy production.
Consequently, much research and development have been made to improve the photocatalysts’ intrinsic reaction efficiency. A study performed on the form factor of photocatalytic systems is vital for their practical application and commercialization, and it is yet to be explored actively.
Current systems available have the potential to fix catalyst powder or nanoparticles onto different surfaces, such as film-type, particulate sheet-type, and flat panel-type platforms, which have been submerged under water.
They experienced practical problems, such as poor mass transfer, leaching of catalysts, and reverse reactions. They also need extra devices to isolate and gather the produced hydrogen from water, which adds to the complication of the device and raises the costs.
At the Center for Nanoparticle Research within the IBS, the research team, headed by Professor Hyeon, developed a new kind of photocatalytic platform that floats on the water for hydrogen production to be done efficiently.
This new platform includes a bilayer structure comprising a lower supporting layer and an upper photocatalytic layer. Both layers are made of a porous structural polymer that grants high surface tension to the platform.
The platform has been fabricated as cryo aerogel, a solid substance filled with gas, displaying low density. Consequently, this elastomer-hydrogel fixed with photocatalysts could float on water.
Clear benefits have been exhibited by this platform in the photocatalytic hydrogen evolution reaction: initially, light attenuation by water is avoided, leading to effective solar energy conversion. Secondly, the product, hydrogen gas, could be diffused quickly into the air, avoiding reverse oxidation reactions and conserving high reaction yield.
Thirdly, as a result of its porosity, the water could be supplied easily to the catalysts situated inside the elastomer-hydrogel matrix. Finally, catalysts have been immobilized within the matrix for long-term operation without leaching issues.
Compared to the conventional submerged platform, the scientists experimentally proved the excellent hydrogen evolution performance of the floatable platform. Moreover, the platform's scalability, which is necessary for possible industrialization, was also illustrated under natural sunlight.
It was verified that around 80 mL of hydrogen could be generated by the floatable photocatalytic platform with the help of titania catalysts and a single copper atom with an area of 1 m2. Even after two weeks of operation in seawater consisting of several microorganisms and floating matter, the platform’s hydrogen evolution performance was not compromised.
The proposed platform can even produce hydrogen from solutions that dissolve household waste, such as polyethylene terephthalate bottles. Consequently, the platform can be a solution for recycling wastes, which contributes to an environment-friendly society.
Jeong Hyun Kim, Center for Nanoparticle Research, Institute for Basic Science
Notably, this study grants a generalized platform for effective photocatalysis that is not just restricted to hydrogen production. It is possible to substitute the catalytic component for several preferred uses without altering the floatable aerogel material properties of the entire platform.
This ensures the extensive applicability of the platform to other photocatalytic reactions, such as oxygen hydrogen peroxide production, evolution reaction, and generation of several organic compounds.
This study makes great progress in the field of photocatalysis and showcases the potential of green hydrogen production at sea with world-class performance. The distinctive material features, high performance, and broad applicability in the field of photocatalysis of our platform will undoubtedly open a new chapter in alternative energy.
Taeghwan Hyeon, Professor, Center for Nanoparticle Research, Institute for Basic Science
Lee, W. H., et al. (2023) Floatable photocatalytic hydrogel nanocomposites for large-scale solar hydrogen production. Nature Nanotechnology. doi.org/10.1038/s41565-023-01385-4.