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Researchers at Berkeley and Argonne labs discover highly active new class of nanocatalysts for fuel cells; more efficient, lower cost

28 February 2014

Chen
Bar chart showing the specific activities of Pt/C, Pt poly-crystal electrode, IL-encapsulated Pt3Ni nanoframes/C, PtNi-Meso-TF, and Pt3Ni(111)-Skin electrode, and the corresponding improvement factors vs. Pt/C. Source: Chen et al. Supplementary Materials. Click to enlarge.

A team led by researchers at Berkeley and Argonne National Labs have discovered a new class of bimetallic nanocatalysts for fuel cells and water-alkali electrolyzers that are an order of magnitude higher in activity than the target set by the US Department of Energy (DOE) for 2017.

The new catalysts, hollow polyhedral nanoframes of platinum and nickel (Pt3Ni), feature a three-dimensional catalytic surface activity that makes them significantly more efficient and far less expensive than the best platinum catalysts used in today’s fuel cells and alkaline electrolyzers. This research, a collaborative effort between DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Argonne National Laboratory (ANL), is reported in the journal Science.

Fuel cells and electrolyzers can help meet the ever-increasing demands for electrical power while substantially reducing the emission of carbon and other atmospheric pollutants. These technologies are based on either the oxygen reduction reaction (fuel cells), or the hydrogen evolution reaction (electrolyzers). Currently, the best electrocatalyst for both reactions consists of platinum nanoparticles dispersed on carbon.

Platinum (Pt) is a highly efficient electrocatalyst for both the cathodic oxygen reduction reaction (ORR) in fuel cells (and metal-air batteries) and the hydrogen evolution reaction (HER) in alkaline electrolyzers. However, the high cost and scarcity of Pt are key obstacles for its broad deployment in fuel cells and metal-air batteries for both stationary and portable applications. Intense research efforts have been focused on developing high-performance electrocatalysts with minimal precious metal content and cost. Specifically, alloying Pt with non-noble metals can reduce the Pt content of electrocatalysts by increasing their intrinsic activity.

… However, these materials cannot be easily integrated into electro- chemical devices but their outstanding catalytic performance needs to be mimicked in nanoparticulate materials that offer high surface areas. Caged, hollow or porous nanoparticles offer a promising approach to meeting these performance goals.

… In this report, we present a novel class of electrocatalysts exploiting structural evolution of bimetallic nanoparticles during which PtNi3 solid polyhedra were transformed into hollow Pt3Ni nanoframes with surfaces that have three-dimensional (3D) molecular accessibility. Controlled thermal treatment of the resulting nanoframes formed the desired Pt-Skin surface structure. Synthesis of Pt3Ni nanoframes can be readily scaled up to produce high-performance electrocatalysts at gram-scale, and importantly our protocol can be generalized toward the design of other multimetallic nanoframe systems.

The solid polyhedral nanoparticles are synthesized in the reagent oleylamine, then soaked in a solvent, such as hexane or chloroform, for either two weeks at room temperature, or for 12 hours at 120 °C. The solvent, with its dissolved oxygen, causes a natural interior erosion to take place that results in a hollow dodecahedron nanoframe. Annealing these dodecahedron nanoframes in argon gas creates a platinum skin on the nanoframe surfaces.

Peidong-fig-1
These schematic illustrations and corresponding transmission electron microscope images show the evolution of platinum/nickel from polyhedra to dodecahedron nanoframes with platinum-enriched skin. Source: Berkeley Lab. Click to enlarge.

In contrast to other synthesis procedures for hollow nanostructures that involve corrosion induced by harsh oxidizing agents or applied potential, our method proceeds spontaneously in air. The open structure of our platinum/nickel nanoframes addresses some of the major design criteria for advanced nanoscale electrocatalysts, including, high surface-to-volume ratio, 3-D surface molecular accessibility, and significantly reduced precious metal utilization.

—Peidong Yang, with Berkeley Lab’s Materials Sciences Division, who led the discovery

In electrocatalytic performance tests at ANL, the platinum/nickel nanoframes when encapsulated in an ionic liquid exhibited a 36-fold enhancement in mass activity and 22-fold enhancement in specific activity compared with platinum nanoparticles dispersed on carbon for the oxygen reduction reaction.

These nanoframe electrocatalysts, modified by electrochemically deposited nickel hydroxide, were also tested for the hydrogen evolution reaction and showed that catalytic activity was enhanced by an order-of-magnitude over platinum/carbon catalysts.

Our results demonstrate the beneficial effects of the hollow nanoframe’s open architecture and surface compositional profile. Our technique for making these hollow nanoframes can be readily applied to other multimetallic electrocatalysts or gas phase catalysts. I am quite optimistic about its commercial viability.

—Peidong Yang

This research was funded by the DOE Office of Science.

Resources

  • Chen Chen, Yijin Kang, Ziyang Huo, Zhongwei Zhu, Wenyu Huang, Huolin L. Xin, Joshua D. Snyder, Dongguo Li, Jeffrey A. Herron, Manos Mavrikakis, Miaofang Chi, Karren L. More, Yadong Li, Nenad M. Markovic, Gabor A. Somorjai, Peidong Yang, and Vojislav R. Stamenkovic (2014) “Highly Crystalline Multimetallic Nanoframes with Three-Dimensional Electrocatalytic Surfaces,” Science doi: 10.1126/science.1249061

February 28, 2014 in Catalysts, Fuel Cells, Hydrogen | Permalink | Comments (13) | TrackBack (0)

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This is good news for the ~50% of cars which are parked by the road without easy access to charging.
For the rest I have always fancied a battery/fuel cell hybrid, so that the weight, bulk and cost of a huge battery is avoided.

Interesting idea Dave: install a light mini fuel cell to slow charge a smaller/medium size EV or PEV battery between uses. The smaller battery being large enough to provide at least minimum charge for most shopping/work trips. A useful alternative to charging stations everywhere. And a smaller (NG?) tank for the lower usage. Hmmm...

For reference the latest Toyota fuel cell stacks use around $1,000 worth of precious metals, around the same as a diesel.
Apparently this might reduce it by a factor of 20 or so, so you would be talking of a few tens of dollars in precious metals per car.

'They were also surprisingly robust. In the laboratory, they subjected the nanoframes to the electrical stresses and strains that they would receive if formulated in a fuel cell that was discharged 10,000 times and only saw a negligable loss of activity. In contrast, platinum–carbon catalysts lose around 40% of their activity during such a test as the platinum dissolves in the electrolyte. The simplicity of the manufacturing process should mean that the process could be readily scaled up to produce much more efficient fuel cells requiring far less platinum in the near future.

Radoslav Adzic, a fuel cell expert at Brookhaven National Laboratory in the US, wants to see the nanoframes in a real fuel cell to prove their industrial readiness as, if nickel were to leak out, it could ‘damage the fuel cell irreversibly’. He also believes that the time to produce the nanoframes still needs to be shortened to produce the catalyst industrially. Nevertheless, he says, ‘the catalyst’s activity is excellent – probably the highest that has been achieved so far’.'

http://fuelcellsworks.com/news/2014/02/28/fuel-cells-put-in-the-frame-with-catalysts-that-need-far-less-platinum/

Some group has a platinum shell over copper around a sulfur sphere that looked good, but this might be even better. If fuel cells are going to be effective, they have to reduce the platinum cost, this could do it.

If this can be mass produced, it would give a real boost to future FCEVs.

Improved FCEVs could then become competitive with extended range BEVs and PHEVs.

The cost of precious metals is not the most critical thing anymore in fuel cell cars, as Toyota for instance has already got them down to around $1,000, or about the same as in a catalytic converter for a diesel car.

It obviously helps though, and can further enhance cost reductions, when Toyota already characterises their progress in these terms:

'At Toyota, recent innovations allowed for the deletion of the external humidifier that keeps the fuel cell stack moist. Instead, a proprietary design allows water to move through the cells' membranes without freezing in cold weather, said Craig Scott, national manager of Toyota's advanced technology group.

More important was Toyota's ability to re-engineer existing hybrid-vehicle parts to work with the upcoming fuel cell car. For instance, the boost converter to crank the fuel cell stack's 200-volt output up to the 600 volts needed for the motors comes from engineering learned with the Prius.

"A lot of the powertrain comes now from our hybrid vehicles, which are our fundamental core architecture and technology," Scott said. "Everything we do now finds its way back to that architecture. That results in monumental cost cuts." '

http://www.autonews.com/article/20140223/OEM06/302249967/test-fleet-shapes-next-step-for-fuel-cell-cars

Toyota is not given to hyperbole, and their characterising their cost cuts as:
'monumental' should be treated with respect.

oxygen reduction reaction

This is at the cathode, there is no mention of the anode, so cost reductions may not be 10 to 1. It does benefit high volume costs and Balance of Plant cost reductions will as well. The high pressure tanks cost, but several auto makers seem determined to debut FCVs in 2015, so we will see.

I'm impressed with the longevity. Active material that shows little degradation over 10,000 cycles seems like a great candidate for grid backup and grid storage systems as well as cars.

The first Hyundai ix35's are already coming off the production line rather than being hand crafted:

'Hyundai Motor Company has delivered the first of its assembly line-produced ix35 Fuel Cell vehicles to the City of Copenhagen in Denmark. They were handed over by Hyundai Motor Europe’s president, Byung Kwon Rhim, during the opening ceremony of Denmark’s first hydrogen refuelling station.

'The 15 ix35 Fuel Cell units are the first hydrogen-powered vehicles manufactured on a production line to be introduced in Europe.

Mr Rhim said: “Hyundai Motor is committed to hydrogen as the fuel of the future for Europe. Delivering assembly-line produced ix35 Fuel Cell is evidence that we have a realistic solution to the region’s sustainable mobility needs.”'

http://www.fuelcellsworks.com/news/2014/02/26/hyundai-motor-delivers-first-15-hydrogen-powered-ix35-fuel-cell-in-europe-2/

IM please to say that im eager to buy when my actual car will be worn out in 2023 approx. I want a car that is efficient, cheap and I want that the hydrogen is been made inside the car by a small water electrolyzer(the fuelcell in reverse)that we can plug and feeded by water so it don't need a bothersome hydrogen infrastructure. Make it today so I will be able to buy it on the used market for cheap. The hydrogen should cost one dollar per kilo and return a whopping 100 mpg without any pollution.

I would venture to say, goodbye Platinum - forever.
http://phys.org/news/2013-07-scalable-carbon-nanotube-based-catalyst-outperforming.html

As far as H2 is concerned, I'd prefer to have it stored in form of synthetic methane (SM) which is identical to NG.

The afore mentioned CNT catalyst is also tolerant to CO poisoning which Platinum is not. So low pressure SM storage offers many advantages in lieu of high pressure H2 storage. BTW, SM is also carbon emmisions neutral.

@yoatmon: The pyridine-functionalized carbon nanotube catalyst only work in an ALKALINE environment. Due to unsolved problems with membrane conductivity and durability, the only currently successful ALKALINE fuel cells run at high temperature and are fed pure hydrogen and pure oxygen, not air nor a carbon-based fuel like methane. So don't say goodbye to your platinum quite yet.

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