Vanderbilt, Nissan and Georgia Tech partner on new low PGM electrospun nanofiber catalysts for improved automotive fuel cells
Vanderbilt University, Nissan North America and Georgia Institute of Technology are collaborating to test a new technique to electospin low-platinum-metal-group (low PGM) electrocatalysts with a proton-conducting binder to improve durability and performance of fuel cell electrodes. The project is one of four awarded a combined $13 million by the Department of Energy program to advance fuel cell performance and durability and hydrogen storage technologies announced last month. (Earlier post.)
The $4.5-million collaboration is based on nanofiber mat technology developed by Peter Pintauro, the H. Eugene McBrayer Professor of Chemical Engineering at Vanderbilt, that replaces the conventional electrodes used in fuel cells. The nanofiber electrodes boost the power output of fuel cells by 30% while being less expensive and more durable than conventional catalyst layers.
The technology has been patented by Vanderbilt and licensed to Merck KGaA in Germany, which is working with major auto manufacturers in applying it to the next generation of automotive fuel cells.
Conventional fuel cells use thin sheets of catalyst particles—typically platinum on carbon powder—mixed with a polymer binder for the electrodes. Pintauro’s approach replaces these solid sheets with mats made from a tangle of electrospun polymer nanofibers fibers. Particles of catalyst are bonded to the fibers.
The very small diameter of the fibers means that there is a larger surface area of catalyst available for hydrogen and oxygen gas reactions during fuel cell operation. The pores between fibers in the mat electrode also facilitate the removal of the waste water. The unique fiber electrode structure results in higher fuel cell power, with a lower requirement for expensive platinum.
Professor Pintauro has been working with electrospun nanofibers for years, with application in fuel cell membranes as well as in electrodes. In earlier research, the Vanderbilt team has used catalysts such as Johnson Matthey HiSpec 4000 Pt/C catalyst powder (40% Pt on carbon black). (Brodt et al., 2013)
Meanwhile at Georgia Tech, biomedical engineering professor Younan Xia has developed a method for carefully controlling the shape of nanoparticle catalyst for fuel cells. In particular, he has produced platinum-nickel nanoparticles with a regular octagonal shape. (Niu et al. 2016)
|TEM images of octahedral nanocrystals with different sizes and compositions: (a) 9 nm Pt1.7Ni, (b) 9 nm Pt3.0Ni, (c) 6 nm Pt2.1Ni, and (d) 6 nm Pt2.7Ni. Credit: ACS, Niu et al. Click to enlarge.|
Theoretically, these particles should be more effective than commercial platinum black powder now used as the oxygen reduction catalyst in hydrogen/air fuel cells.
The combination of the Georgia Tech catalyst with Vanderbilt’s nanofiber electrode technology could be a game-changer for the development and commercialization of automotive fuel cells.—Peter Pintauro
In the new DOE project, Pintauro’s group will make nanofiber mat electrodes containing Xia’s nanoparticle catalysts. The electrodes will then be sent to Nissan Technical Center North America where a team of researchers led by Nilesh Dale, the manager of fuel cell research, will evaluate their performance under automotive operating conditions.
The research teams will also be working with scientists at the national labs—Oak Ridge National Laboratory, Los Alamos National Laboratory, the National Renewable Energy Laboratory, and Lawrence Berkeley National Laboratory—in an effort to improve the scientific understanding of why fuel cells work better with nanofiber mat electrodes.
Right now, much of the research work on fuel cell electrodes is very Edisonian. It is mainly trial and error experiments. We don’t know what will happen when we change the composition or structure of the electrodes in hydrogen/air fuel cells. With a better understanding of the interdependence of composition and nanostructure for fiber electrodes, we could accelerate the pace of our research, which would help us to achieve the cost and performance targets needed for automotive fuel cell commercialization.—Peter Pintauro
Matthew Brodt, Ryszard Wycisk, and Peter N. Pintauro (2016) “Nanofiber Electrodes with Low Platinum Loading for High Power Hydrogen/Air PEM Fuel Cells” J. Electrochem. Soc. 160(8): F744-F749; doi: 10.1149/2.008308jes
Zhang, W. and Pintauro, P. N. (2011) “High-Performance Nanofiber Fuel Cell Electrodes,” ChemSusChem, 4: 1753–1757 doi: 10.1002/cssc.201100245
Jason B. Ballengee and Peter N. Pintauro (2011) “Composite Fuel Cell Membranes from Dual-Nanofiber Electrospun Mats” Macromolecules 44 (18), 7307-7314 doi: 10.1021/ma201684j
Guangda Niu, Ming Zhou, Xuan Yang, Jinho Park, Ning Lu, Jinguo Wang, Moon J. Kim, Liduo Wang, and Younan Xia (2016) “Synthesis of Pt–Ni Octahedra in Continuous-Flow Droplet Reactors for the Scalable Production of Highly Active Catalysts toward Oxygen Reduction” Nano Letters 16 (6), 3850-3857 doi: 10.1021/acs.nanolett.6b01340
Aleksey Ruditskiy, Hsin-Chieh Peng, and Younan Xia (2016) “Shape-Controlled Metal Nanocrystals for Heterogeneous Catalysis” Annual Review of Chemical and Biomolecular Engineering, Vol. 7: 327 -348 doi: 10.1146/annurev-chembioeng-080615-034503
Jingyi Chen, Byungkwon Lim, Eric P. Lee, Younan Xia (2009)Shape-controlled synthesis of platinum nanocrystals for catalytic and electrocatalytic applications, Nano Today, Volume 4, Issue 1, February 2009, Pages 81-95 doi: 10.1016/j.nantod.2008.09.002