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Chemical and Biological Engineering

Manos Mavrikakis

Chemical and Biological Engineering

New nanoparticle catalyst
brings fuel-cell cars closer
to the showroom

Surrounding a nanoparticle of ruthenium with a monolayer or two of platinum atoms, Professor Manos Mavrikakis and University of Maryland Professor of Chemistry and Biochemistry Bryan Eichhorn created a robust, room-temperature chemical catalyst that could pave the way for more efficient hydrogen fuel cell vehicles.

Currently, most of the world’s hydrogen supply is derived from fossil fuels in a process called reforming, which yields a mixture of carbon monoxide and hydrogen. However, carbon monoxide poisons the fuel cell catalyst. Therefore, hydrogen produced from reforming needs to be purged from carbon monoxide prior to entering the fuel cell. For that cleaning process, industry has been using expensive all-platinum catalysts.

The researchers’ new catalyst dramatically improves this hydrogen purification reaction and leaves more hydrogen available to make energy in the fuel cell.

A conventional ruthenium and platinum catalyst must reach 158 degrees Fahrenheit to purge the carbon monoxide. Combined as core-and-shell nanoparticles, however, the ruthenium-platinum catalyst can operate at room temperature. The lower the temperature at which the catalyst activates the reactants, the more energy is saved.

Both the core-and-shell nanostructure and a novel reaction mechanism—hydrogen-assisted carbon-monoxide oxidation—are key to making the catalyst work, says Mavrikakis.

While the breakthrough is important to the development of fuel-cell technology, the researchers say it’s even more significant to catalysis research as a whole. Not only did the researchers, including graduate students Anand Nilekar of UW-Madison and Selim Alayoglu of Maryland, use a theoretical approach to identify the catalyst materials, but their nanoscale approach to fabricating the catalyst resulted in a nano-architecture different from when ruthenium and platinum are combined in bulk. Pairing these approaches could bridge the gap between surface science and catalysis, opening new paths to novel and more energy-efficient materials discovery for a variety of industrially important chemical processes.

Strength in numbers:
Manipulating cells for bio applications

Combining both experimental and computational approaches, Assistant Professor Jennifer Reed models biological systems, such as metabolism and regulation, to better understand and predict cell behavior. Her research may enable scientists to design microbes with desired characteristics that include enhanced production yields of desired products, such as ethanol.

“My group is interested in building, analyzing and using metabolic and regulatory models of organisms involved in bioremediation, biofuels production or biotechnology applications,” says Reed.

Central to Jennifer Reed’s research in this field of systems biology are computational approaches that enable her and her students to analyze and integrate various types of high-throughput data, including genomic, proteomic and transcriptomic data. From their computational models, Jennifer Reed and her students generate hypotheses about cellular responses to genetic or environmental perturbations or biological network structure. They then can test these model-generated hypotheses experimentally in their lab.

They also are developing computational methods to help them identify and develop new strains or cell lines with desired phenotypes. “For example, we can determine computationally what enzyme encoding genes we should introduce or remove from an organism in order to improve ethanol production,” says Jennifer Reed.

She and her students also hope to use their models to identify novel gene functions or new regulatory interactions, further clarifying the roles gene products play within the cell. “By developing new computational methods, we will increase the utility of models in biological research, as well as improve the capabilities of organisms for a variety of applications,” she says.

Sustainability through synthetic biology

The most abundant energy source on the planet, sunlight could free society from relying on fossil fuels. Yet, converting solar energy into a usable form remains a formidable challenge.

Taking their cue from photosynthetic organisms, Assistant Professor Brian Pfleger and his students are developing ways to harness the solar energy stored in biomass. They are using tools in the emerging field of synthetic biology to engineer microorganisms to convert photosynthetically captured carbon dioxide into fuels and chemicals.

Synthetic biology combines science and engineering skills to design and construct new biological systems from known biological parts, says Pfleger. For instance, synthetic biology gives engineers the tools to synthesize and regulate new metabolic pathways. These pathways give microorganisms the capability to convert renewable resources into useful products. “By studying the parts needed to convert biomass into chemicals, engineers can assemble new factories to efficiently synthesize a wide array of compounds, including fuels, medicines, solvents, materials and other specialty chemicals,” says Pfleger.

Currently, he and his students are studying enzymes to produce hydrocarbon fuels and bioplastics. They are also developing tools to use cellulose and carbon dioxide as metabolic inputs. Eventually, they will integrate these parts into microbial hosts, resulting in new methods of sustainably producing chemicals.

In addition to department faculty, Pfleger’s collaborators include faculty, staff and students in the U.S. Department of Energy-funded Great Lakes Bioenergy Center at UW-Madison. These interactions help integrate Pfleger’s synthetic biology research with ongoing work in the life sciences, biotechnology, catalysis, materials science, nanotechnology and computational modeling. “These unique resources, available only at UW-Madison, create an ideal environment for students to develop sustainable technologies and bring them into practice,” he says.

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