Jagged Platinum nanowires achieve record mass activity and cost reduction for hydrogen fuel cells

Jagged Platinum nanowires achieve record mass activity and cost reduction for hydrogen fuel cells

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Shaping platinum into ultrafine jagged nanowires and using it as a catalyst in hydrogen fuel cells would dramatically increase efficiency, lower cost.

An international team including a CNR-ICCOM researcher develops a method that allows a 50-fold reduction in the amount of platinum. Jagged platinum nanowires are obtained by removing nickel from Pt-Ni regular alloy nanowires.

An international team including a CNR-ICCOM researcher has demonstrated how shaping platinum into the form of nanoscale wires exhibiting jagged structure allows for a 50-fold reduction in the amount of this precious metal used as catalysts in hydrogen fuel cells thus dramatically lowering their cost and potentially enabling e.g. widespread use of cars fueled by hydrogen. Hydrogen fuel cells are devices realizing the controlled combustion of hydrogen and atmospheric oxygen to produce electricity and the only byproduct is water vapor. Consequently, they represent one of the most attractive possibilities for a clean and renewable technology for vehicles, avoiding use of nonrenewable fossil fuels (such as oil) whose emissions (such as carbon dioxide) are responsible for global warming and atmospheric pollution. Hydrogen fuel cells are reliant on catalysts, i.e., substances that accelerate electrochemical reaction so as to produce the energy for power generation at the required rate, but this is still a slow process especially at the cathode where oxygen reduction reaction occurs. At present catalysts based on platinum are the only viable options, but the amount of this rare and precious metal required in each device is so high to make widespread adoption of hydrogen fuel cells and the cars powered by them impossible (e.g., using the present technology there is not enough platinum on earth to build a billion hydrogen cars). Each one of the major auto companies spends about 200 million Euros each year in research to develop hydrogen cars, and one of the major issues is in fact finding catalysts much more efficient than the ones presently available.

But in a study published in Science on November 17th 2016, the research team showed how shaping platinum into nanowires that exhibit characteristic jagged-shaped structures create novel, highly active catalytic sites thus reducing reaction energy barriers, vastly accelerating the rate of oxygen reduction reaction, and hugely increasing the efficiency of the catalyst. This, together with the nanoscale dimension of the wires such that most platinum is exposed on the surface instead of being buried within the wire body and making little contribution to the reaction, entails that the amount of platinum needed to make one fuel cell is reduced by a factor of 50 with respect to present devices, thus dramatically cutting costs and potentially making world-wide diffusion of hydrogen fuel cells compatible with natural abundance of the rare and precious metal.

According to Alessandro Fortunelli of CNR-ICCOM in Pisa “This work is a perfect example of how fundamental research leading to understanding and control of processes at the microscopic level can enable breakthrough progress in nanotechnology with beneficial effects for environment and society at large. The present study has been supported by the USA Department of Energy and the USA National Science Foundation, but it is worthwhile recalling that its theoretical bases were laid in a previous study by some of the present co-authors, in a collaboration made possible by a Short-Term Mobility grant of CNR.”

Other authors hailed from the University of California at Los Angeles (Los Angeles, USA), the California Institute of Technology (Pasadena, USA), Tsinghua University (Beijing, China), the Chienese Academy of Science (Beijing, China), the California State University (Long Beach, USA), Northeastern University (Boston, USA), and the Lawrence Berkeley National Laboratory (Berkley, CA, USA).

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