Tuesday, May 24, 2022

Solar energy can be cleanly converted into storable hydrogen fuel

Greenhouse gas emissions need to be significantly reduced to avoid potentially catastrophic effects of climate change, with access to clean and affordable energy needed to eliminate our reliance on fossil fuels. Many researchers and companies are working to address this issue and replace fossil fuels through the use of hydrogen, a storable fuel.

When used in a fuel cell, hydrogen does not emit any greenhouse gasses at the point of use and can help decarbonize sectors such as shipping and transportation, where it can be used as a fuel, as well as in manufacturing industries. However, most hydrogen produced today is almost entirely supplied from natural gas and coal, producing greenhouse gases. And therefore, green hydrogen production is urgently needed.

New research led by the University of Strathclyde suggests that solar energy can be accessed and converted into hydrogen – a clean and renewable fuel.

Green hydrogen is produced from water using a photocatalyst – a material that drives the decomposition of water into hydrogen and oxygen using sunlight. The new study suggests that using a photocatalyst under simulated sunlight facilitates the decomposition of water when loaded with an appropriate metal catalyst – in this case, iridium.

The reported photocatalyst can access solar energy through the energetically unfavorable process to generate a storable energy carrier in the form of hydrogen from water. The hydrogen can then be converted cleanly into electricity in a fuel cell, with water being the only side-product.

“This is a significant step forward for us as previous systems have relied on using so-called sacrificial reagents to drive the reaction. Sacrificial agents are the electron donors which reduce the recombination tendency of electrons and accelerate the rate of hydrogen generation. Although these allow us, researchers, to understand systems, they made them ‘energy negative,'” said Principal Investigator Dr. Sebastian Sprick from Strathclyde.

“This study provides a way forward to optimize further as it is not sacrificial. The photocatalysts (polymers) are of huge interest as their properties can be tuned using synthetic approaches, allowing for simple and systematic optimization of the structure in the future and to optimize activity further.”

Researchers say another potential advantage is that polymers are printable, allowing the use of cost-effective printing technologies for scale-up – just like newspaper printing. “This will also be important to produce hydrogen at scale to address climate change effectively,” added Dr. Sprick.

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