A single device that produces fuel and oxidizer from water and converts fuel and oxygen into electricity and water when switched on has many advantages for ground, space and military applications. The development of efficient unitized regenerative fuel cells, or so-called URFCs, from those with low environmental impact to those with high energy density, has been in the eyes of researchers for many years.
However, to be truly efficient, URFCs require bifunctional catalysts. This means that in electrolytic cell mode, the catalyst must promote the decomposition of water into hydrogen and oxygen, and in fuel cell mode, it must promote recombination with water. A team of researchers currently working in the lab of Professor Vijay Ramani, Roma B. & Raymond H. Wittcoff Distinguished University has discovered excellent dual functionality. catalyst For oxygen electrodes.
Their work was published in the journal Minutes of the National Academy of Sciences..
“Unlike hydrogen electrodes, where platinum is an effective bifunctional catalyst, it is very difficult to identify a suitable catalyst for oxygen. electrode Because the rate of oxygen reduction and oxygen evolution is slow. ” The author is Pralay Gaen, a postdoctoral fellow at the Ramani Lab at Washington University in St. Louis’ McKelby Institute of Technology and currently working at Intel.
The work of Srey Saha and Gayen, postdoctoral fellows in Ramani’s lab, is based on the first principle of taking into account the basic properties of various substances before heading to the lab to test potential catalysts. Guided by.
Together with former undergraduate researcher and co-author Xinquan Liu, the team finally identified and developed Pt-pyrochlore, a composite of platinum and lead ruthenate pyrochlore. As a result, high dual functionality was obtained.
The “bifunctional index” is a measure of the ability of a catalyst to facilitate both forward and reverse reactions. “We want to lower the index,” said Kritika Sharma, who holds a PhD. Engineering student. “Zero, ideally” The bifunctionality index of this new catalyst is 0.56 volts, which is very low compared to other catalysts reported. When used in laboratory-developed URFC devices, the catalyst enabled 75% regenerative energy efficiency (RTE). This is the highest round-trip efficiency reported for this type of URFC.
Developed with such high efficiency, the URFC is ideal for applications such as submersibles, drones, spacecraft, and space stations, as well as off-the-grid energy storage.
Vijay Ramani et al, High performance AEM unitized regenerative fuel cell using Pt-pyrochlore as bifunctional oxygen electrode catalyst, PNAS, DOI: 10.1073 / pnas.2107205118 , www.pnas.org/content/118/40/e2107205118
Washington University in St. Louis
Quote: The new catalyst helps to combine the fuel cell and battery into one device (October 6, 2021).
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The new catalyst helps combine fuel cells and batteries into one device
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