Gilding technique inspired by ancient Egyptians may spark better fuel cells for tomorrow's electric cars

December 20, 2017 by Phil Sneiderman, Johns Hopkins University
Gilding technique inspired by ancient Egyptians may spark better fuel cells for tomorrow's electric cars
Chao Wang (right) inspects a glass vial containing cobalt cores, each coated with a thin layer of platinum. At left is postdoctoral fellow Lei Wang. Credit: Will Kirk / Homewood Photography

To make modern-day fuel cells less expensive and more powerful, a team led by Johns Hopkins chemical engineers has drawn inspiration from the ancient Egyptian tradition of gilding.

Egyptian artists at the time of King Tutankhamun often covered cheaper metals (copper, for instance) with a thin layer of a gleaming precious such as gold to create extravagant masks and jewelry. In a modern-day twist, the Johns Hopkins-led researchers have applied a tiny coating of costly platinum just one nanometer thick—100,000 times thinner than a human hair—to a core of much cheaper cobalt. This microscopic marriage could become a crucial catalyst in new fuel cells that generate electric current to power cars and other machines.

The new fuel cell design would save money because it would require far less platinum, a very rare and expensive metal that is commonly used as a catalyst in present-day electric cars. The researchers, who published their work earlier this year in Nano Letters, say that by making electric cars more affordable, this innovation could curb the emission of carbon dioxide and other pollutants from gasoline- or diesel-powered vehicles.

"This technique could accelerate our launch out of the fossil fuel era," said Chao Wang, a Johns Hopkins assistant professor in the Department of Chemical and Biomolecular Engineering and senior author of the study. "It will not only reduce the cost of fuel cells. It will also improve the energy efficiency and power performance of clean electric vehicles powered by hydrogen."

In their journal article, the authors tipped their hats to the ancient Egyptian artisans who used a similar plating technique to give copper masks and other metallic works of art a lustrous final coat of silver or gold. "The idea," Wang said, "is to put a little bit of the precious treasure on top of the cheap stuff."

He pointed out that platinum, frequently used in jewelry, also is a critical material in modern industry. It catalyzes essential reactions in activities including petroleum processing, petrochemical synthesis, and emission control in combustion vehicles, and is used in fuel cells. But, he said, platinum's high cost and limited availability have made its use in clean energy technologies largely impractical—until now.

"There's a lot more cobalt out there than platinum," said lead author and Johns Hopkins post-doctoral fellow Lei Wang, who is not related to Chao Wang. "We've been able to significantly stretch the benefits of platinum by coating it over cobalt, and we even managed to enhance the activity of platinum at the same time."

Earlier attempts to plate precious metals on non-precious materials were largely stymied by galvanic replacement reactions—oxidation of the non-precious metal. In this study, the team successfully suppressed such reactions by introducing carbon monoxide, a gas molecule that strongly binds to cobalt, protecting it from oxidation.

Not only did the cobalt-platinum nanoparticles reduce the usage of platinum; they performed almost 10 times better than platinum alone. The researchers said this enhanced catalytic activity resulted from both the maximized exposure of platinum atoms on the surface and from interactions between the two metals.

"The intimate contact between cobalt and platinum gives rise to compressive strain," Lei Wang said. "It shortens the distance between platinum atoms and makes the chemical reactions more feasible on the surface."

Because and other rare metals play key roles in many industrial applications, the implications of this work extend beyond fuel cells. Currently, the team is working on adapting their technique to other precious metals and non-precious substrates. New developments will target further applications of such materials in chemical conversions of hydrocarbons.

"Many reactions that depend on precious metal catalysts could be rendered cheaper and more effective by taking advantage of our technology," Chao Wang said. "At a time when we are becoming painfully aware of the limits of our non-renewable sources of energy and materials, this technique points us in a very welcome new direction."

Explore further: Nanoalloys 10 times as effective as pure platinum in fuel cells

More information: Lei Wang et al. Plating Precious Metals on Nonprecious Metal Nanoparticles for Sustainable Electrocatalysts, Nano Letters (2017). DOI: 10.1021/acs.nanolett.7b00046

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gkam
1 / 5 (1) Dec 20, 2017
How long before we essentially kill the ICE for transportation?
Nik_2213
not rated yet Dec 20, 2017
#G: IMHO opinion, a long time. The ICE is a mature tech and, with eg turbo-assist and fuel injection, usefully efficient. Also, takes about two minutes to top off your fuel tank via a long-established, global distribution network. Even better, you can conveniently tote a gallon or ten of spare 'gas'. Try that in a non-hybrid electric vehicle !!

There are valuable niches for purely electric vehicles. Regular routes or 'local' usage suit them. Delivery panel-vans and 'city' taxis are logical applications. Supermarket etc logistics are so carefully organised that distribution depots should adapt easily by dropping the semi-trailer...
==
Our local hospital's senior cardiac surgeon bought a nice electric car. It had ample range for his long commute, he'd recharge at home overnight. Then his bleeper went. His car's battery did not yet have enough range for this second run, he had to call a taxi. A week later, the hospital tore up a grass verge and installed several charging bays..
gkam
1 / 5 (1) Dec 20, 2017
"Also, takes about two minutes to top off your fuel tank via a long-established, global distribution network."

That's a big difference, but with 600 mile batteries coming (really), and faster chargers it will work out. The gas pump fueling your car does so at an equivalent rate of 5 Megawatts. Our chargers are rated in kW right now.
MR166
not rated yet Dec 20, 2017
If li-on powered vehicles are 5 years away from wide acceptance then H2/fuel cell powered vehicles are 25 years away from acceptance. At least we have a grid to recharge them even if it has to be upgraded to do so. Whereas a whole new infrastructure has to be developed for H2 and all of the problems involved are far from being solved.

BTW being able to plate nanometer thick platinum onto a surface is a huge breakthrough with many cost saving benefits since platinum catalysts are used extensively in chemical processes . It is too bad that the author chose to denigrate this achievement by trying to tie it into yet another pie in the sky dream.

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