Communicating Science (15w212)

Hydrogen fuel cells can be used to provide electricity for numerous applications, such as electric motors. They are conceptually similar to batteries, but the contents are not self-contained. A supply of hydrogen gas and molecular oxygen is needed to produce electricity. These cells have several advantages, for example, they are non-polluting, low maintenance, silent, safe and have a high energy efficiency in comparison to gas engines. However, the majority of hydrogen gas is produced from petroleum cracking and reforming reactions. Thus, finding alternatives to generate hydrogen gas, without depending on petroleum is crucial. Existing alternative processes or technologies that generate hydrogen gas include photoelectrochemical cells, electrolysis of sodium chloride and gasification.

Hydrogen fuel cell: How it works Source: Wikimedia Commons

In an article published by Nature Chemistry, scientists from Indiana University have created an efficient biomaterial that catalyzes the production of hydrogen. In the study, the [NiFe]-hydrogenases from the bacteria E.Coli were used as the target for the hydrogen-producing catalysts due to their oxygen-tolerant nature and ability to be incorporated into biomaterials. Hydrogenases are enzymes that catalyze the reduction of protons to form hydrogen gas. The hydrogenase enzyme of E.Coli is encoded in a six-gene operon (a unit regulating the expression of the protein), of which the first two genes, hyaA and hyaB encode for the small and large subunits of the enzyme, respectively. One plasmid (circular DNA strand of a bacterium) was engineered to contain the two genes of the hydrogenase enzyme, hyaA and hyaB, both fused to a scaffold protein. On a separate plasmid, the coat protein gene was present with a different promotor. The scientists induced expression of the hyaA and hyaB genes and expression of the coat protein gene followed resulting in the self-assembly of a shell surrounding the matured hydrogenase enzyme.

The ‘viral shell’. Source: Wikimedia Commons

The viral shell was shown to provide protection from protease (an enzyme that breaks down proteins), thermal denaturation and air exposure. The encapsulated hydrogenase enzyme is 100 times more active than the free enzyme and the coat protein offers protection to its cargo. Utilizing the enzyme’s remarkable capability to produce hydrogen gas, paired with the virus’ ability to self-assemble has resulted in a renewable, efficient and environmentally friendly biomaterial that could be utilized as an alternative fuel source in the future.

As mentioned, roughly 95% of hydrogen gas is generated from fossil fuels and the other 5% is generated from alternative processes. The conclusion of this research is indeed exciting and offers another potential alternative aimed to decrease our dependence on fossil fuels for hydrogen gas production. Hopefully, this process could reduce the operation costs of hydrogen fuel cells, given that conventional methods rely on using complex and expensive infrastructure for the production of hydrogen gas. It is uncertain however, how or if this process will be used to produce hydrogen gas on an industrial scale, given that the article does not mention how much hydrogen gas is produced from these nano-catalysts. The leading professor of the study, says the next step is to “[incorporate] this material into a solar-powered system”.

Video by: Gregor Scott