A fuel cell converts chemical energy into electrical energy via hydrogen combustion. Though it is considered to be a clean technology - because it does not emit greenhouse gases - fuel cells do use costly rare metal catalysts1, such as platinum, to oxidize hydrogen and reduce oxygen.
In recent years, the identification of biocatalysts, enzymes with remarkable properties, has revitalized research in this area: their oxygen, and especially hydrogen, transformation activity is comparable to that of platinum. Hydrogenase activity was, until recently, inhibited by oxygen and therefore incompatible with use in cells.
For several years, researchers in the Laboratoire of Bioénergétique et Ingénierie des Protéines (CNRS/Aix-Marseille Université) have been developing a new generation of biocells. They have replaced the chemical catalyst (platinum) with bacterial enzymes: at the anode2, hydrogenase (key for converting hydrogen into many microorganisms), and at the cathode3, bilirubin oxidase.
They have now identified a hydrogenase that is active in the presence of oxygen and resistant to some platinum inhibitors like carbon monoxide. In collaboration with the Centre de Recherche Paul Pascal (CNRS/Université de Bordeaux), they also explored biodiversity to identify heat-stable enzymes that can withstand temperatures between 25°C and 80°C.
To shift these bioprocesses from the laboratory to industrial development two major hurdles had to be overcome. In 2014, their first prototype was limited by both the low power it generated and by lack of enzyme stability. So they needed a change of scale, yet had to retain the enzymes' activity and protect them from any inhibitors.
A third major problem was how to reduce costs, so among other things, they had to minimize the amount of enzyme used. All of these issues required fundamental and multidisciplinary study intended to shine light on the factors that limit bioelectrocatalysis.
By progressively incorporating the two heat-stable enzymes in a carbon-based architecture, the researchers solved these three problems. A carbon felt with suitably adapted porosity is the host structure for the enzymes, and also serves as protection against chemical species generated when oxygen is reduced, which change enzyme activity. So the cell can function without loss of performance for several days.
Using this controlled architecture and enzymes' intrinsic properties, the researchers have managed for the first time to quantify the proportion of enzymes participating effectively in the current, demonstrating that the currents delivered by the biocatalyst are very similar to target results for platinum.
They have also developed a numerical model to determine the cell's optimal geometry. So these biocells appear to be an alternative to classic fuel cells: biomass can be used to provide both the fuel (hydrogen) and the catalyst (the enzymes), which are by nature, renewable.
Anne-Sophie Boutaud | EurekAlert!
Researchers take next step toward fusion energy
16.11.2017 | Texas A&M University
Desert solar to fuel centuries of air travel
16.11.2017 | SolarPACES
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses