Sophisticated enzyme-mimic enables efficient hydrogen production

January 26, 2016

Researchers from the University of Amsterdam's Van 't Hoff Institute for Molecular Sciences (HIMS) have developed a new catalyst that paves the way for low-cost, large-scale hydrogen-production. The researchers, led by Professor Joost Reek, recently presented their enzyme-mimicking catalyst in Science Advances, the peer-reviewed open-access initiative of the publisher of Science.

A hydrogen-based sustainable economy depends on technology to generate molecular hydrogen using sustainable solar or wind energy. Catalytic chemistry already enables this by using water as feedstock and platinum and iridium as active materials. However, because such elements are scarce and expensive this technology cannot be applied at the required global scale.

Looking at nature

To overcome this hurdle, chemists have started looking toward nature where so-called iron-iron hydrogenase enzymes catalyse the conversion (reduction) of protons to with a performance comparable to platinum. It is a major challenge to apply these enzymes directly in hydrogen-producing devices since their isolation is difficult and their performance in air poor. Nevertheless, their high efficiency has spurred the search for comparable iron-based molecular complexes that also can produce hydrogen with a platinum-like performance.

Over the last decade, numerous synthetic complexes have been prepared that structurally and functionally mimic the active site of hydrogenase enzymes. Most of these 'synthetic hydrogenases' show serious drawbacks such as a low efficiency and stability and the requirement of organic solvents. Hydrogenase-mimics that perform efficiently in an aqueous environment while being tolerant to air have until now not been reported.

Characteristic feature

In the current edition of Science Advances, the researchers offer a possible solution by presenting a new oxygen-tolerant iron-iron hydrogenase-mimic that not only achieves efficient proton reduction in aqueous media but also displays electron storage and pre-organisation in close proximity to the active site - a feature characteristic of working natural enzymes.

The Amsterdam-designed synthetic hydrogenase contains a redox-active phosphorous ligand that acts as an electron reservoir and actively partakes in the reduction of protons. It donates an electron to the during the catalytic cycle when needed. As a result, the catalyst displays high turnover numbers (TON) and turnover frequencies (TOF).

Combining this high performance with the operation in aqueous media and the tolerance towards oxygen, this new hydrogenase-mimic is a major step toward the development of catalysts for inexpensive large-scale hydrogen-producing devices. Further development will be directed toward analogs that operate at lower overpotentials and can be efficiently implemented in devices (for example, by anchoring to electrodes or metal-organic frameworks).

Explore further: Scientists create 'nano-reactor' for the production of hydrogen biofuel

More information: R. Becker et al. An iron-iron hydrogenase mimic with appended electron reservoir for efficient proton reduction in aqueous media, Science Advances (2016). DOI: 10.1126/sciadv.1501014

Related Stories

Synthetic catalyst mimics nature's 'hydrogen economy'

May 18, 2009

By creating a model of the active site found in a naturally occurring enzyme, chemists at the University of Illinois have described a catalyst that acts like nature's most pervasive hydrogen processor.

Study advances hydrogen production efforts

December 22, 2015

Researchers at the Energy Department's National Renewable Energy Laboratory (NREL) have made advances toward affordable photoelectrochemical (PEC) production of hydrogen.

Recommended for you

Oxygen can wake up dormant bacteria for antibiotic attacks

December 8, 2016

Bacterial resistance does not come just through adaptation to antibiotics, sometimes the bacteria simply go to sleep. An international team of researchers is looking at compounds that attack bacteria's ability to go dormant ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.