Light Delivers Hydrogen from Nonphotosynthetic Microorganisms

A team in Portugal has introduced a method for the sustainable conversion of solar energy into hydrogen, relying on biohybrid systems — combinations of nonphotosynthetic materials, bacteria, and semiconductor nanoparticles. The ability of those bacteria to produce high levels of hydrogen, paired with the cadmium sulfide nanoparticles’ efficiency in capturing light, initiated a direct energy transfer that the researchers said demonstrated a replicable and sustainable fuel-generation process.

Many existing methods for the production of hydrogen are based on renewable energy, necessitating the continuous development of new and improved renewal options. Obstacles include high-cost materials and elements, as well as the environmental consequences of methods using rare metal catalysts.

In the research, Inês Cardoso Pereira, head of the Bacterial Energy Metabolism Lab at Instituto de Tecnologia Química e Biológica António Xavier (ITQB NOVA), a scientific research and advanced training institute of Universidade NOVA de Lisboa, and colleagues investigated light-driven, biohybrid hydrogen production based on multiple bacteria. While all the biohybrids in the work successfully generated hydrogen, one, made from a bacterium found in soils, demonstrated the highest degree of activity. The bacterium, Desulfovibrio desulfuricans, contains high levels of hydrogenases, which are the enzymes involved in the production of hydrogen.

Those enzymes are also efficient in producing self-producing nanoparticles of extracellular sulfide. The nanoparticles can capture light, allowing the bacterium to produce quantities of hydrogen.

The researchers showed the effectiveness of the process even without the addition of expensive and toxic mediators. The mechanism was also stable.

As biohybrid-based research continues, Pereira said, so too will the value of pairing the high catalytic efficiency of certain biological systems with synthetic materials that show effectiveness in capturing solar and/or electrical energies. The recently developed system is a strong candidate for the development of a bioreactor prototype, said Mónica Martins, an ITQB NOVA researcher.

In additional work aimed at sustainable decarbonization techniques, the team is currently studying the possibility of using biohybrid systems for carbon dioxide reduction to compounds.

This work was supported by Fundação para a Ciência e a Tecnologia (FCT) and R&D units MOSTMICRO-ITQB and GREEN-IT Bioresources for Sustainability.

The research was published in Angewandte Chemie International Edition (www.doi.org/10.1002/anie.202016960).