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Bunched Pt-Ni alloy nanocages as efficient catalysts for fuel cells

An international team of researchers has synthesized one-dimensional bunched platinum-nickel (Pt-Ni) alloy nanocages with a Pt-skin structure for the oxygen reduction reaction in fuel cells. The nanocages display high mass activity (3.52 amperes per milligram platinum) and specific activity (5.16 milliamperes per square centimeter platinum)—nearly 17 and 14 times higher respectively as compared with a commercial platinum on carbon (Pt/C) catalyst. A paper on their work is published in Science.

The catalyst exhibits high stability with negligible activity decay after 50,000 cycles. Experimental results and theoretical calculations reveal the existence of fewer strongly bonded platinum-oxygen (Pt-O) sites induced by the strain and ligand effects.

The fuel cell supported by this catalyst delivers a current density of 1.5 amperes per square centimeter at 0.6 volts and can operate steadily for at least 180 hours.

Platinum (Pt) is the most active electrocatalyst for the oxygen reduction reaction (ORR) in fuel cells and metal-air batteries with promising stability. Nevertheless, the state-of-the-art Pt catalysts still lack activity and stability with respect to the cost and availability for large-scale commercial implementation.

Engineering the near-surface composition of nanostructured Pt alloys represents one promising approach to enhance the electrocatalytic performance of Pt-based electrocatalysts, in which the exposure of highly active sites with optimum performance can be maximized.

Adding other transition metals can enhance the catalytic performance via ligand and strain effects through modifying the binding strength of Pt-oxygen intermediates. The introduction of open nanostructures, including hollow and porous nanoparticles such as nanocages (NCs) and nanoframes, may help in achieving this goal and also enhance mass transfer.

—Tian et al.

To prepare the nanocages, the team first prepared 1D Pt-Ni bunched nanospheres (BNSs) by reducing Pt and Ni precursors with varying ratios by a one-pot solvothermal method. Treatment under acidic conditions selectively removed Ni species to leave 1D Pt-Ni BNCs with ultrathin walls composed of a platinum skin and a residual platinum-nickel alloy below this skin.

Ptni

Schematic illustration of the preparation of Pt-Ni BNCs. Tian et al.


This work provides an effective strategy for the rational design of Pt alloy nanostructures and will help guide the future development of catalysts for their practical applications in energy conversion technologies and beyond.

—Tian et al.

Resources

  • Xinlong Tian, Xiao Zhao, Ya-Qiong Su, Lijuan Wang, Hongming Wang, Dai Dang, Bin Chi, Hongfang Liu, Emiel J.M. Hensen, Xiong Wen (David) Lou, Bao Yu Xia (2019) “Engineering bunched Pt-Ni alloy nanocages for efficient oxygen reduction in practical fuel cells” Science Vol. 366, Issue 6467, pp. 850-856 doi: 10.1126/science.aaw7493

Comments

Davemart

It will be interesting to see who modifies their position in the light of development , and who operates solely on a :

'Batteries good'
'Hydrogen bad'.

basis.

SJC

negligible activity decay after 50,000 cycles...
That sounds good.

Davemart

@SJC

Calculated on the same basis as Tesla fans are claiming million mile batteries, at one cycle per day a stationary fuel cell facility should be good for around 142 years! ;-)

Of course in the real world calendar life and all sorts of other factors intervene, but 50,000 cycles with negligible degradation is a good place to start from.


SJC

Bus fuel cells have run for more than 20,000 hours.

Paroway

This is still lab level work, not commercialized, and it still requires a fuel source. Hydrogen? Where is the infrastructure? Transporting the fuel, generating the hydrogen, what is the efficiency? Still can't match the price of electricity, especially in the vast majority of cases where it happens at home. So until proven otherwise.....
'Batteries good'
'Fuel cells bad'

Paroway

OK, 'Batteries good', 'fuel cells not as good'

yoatmon

I'm happy to see that at least a few, now and than, are beginning to grasp the meaning of "Fool Cells" and the implications of a complete H2 Infrastructure. It is nothing more than a frantic attempt of "big oil" to keep their cash cows in their own pasture.

SJC

Hydrogen can be produced at the fueling stations for fleets of trucks and buses. This is not a problem unless you are stuck on cars and gasoline stations.

electric-car-insider.com

Charles Morris, writing in Charged:

"According to RMI’s Breakthrough Batteries Report, venture capital firms invested over $1.4 billion in battery tech in the first half of 2019 alone. Total manufacturing investment - both previous and planned through 2023 - amounts to around $150 billion. By 2023, the capital cost for new battery manufacturing capacity is expected to decline by more than half compared to 2018. Battery costs could drop to $87/kWh by 2025 (in March, Bloomberg estimated the current average cost at $187/kwh)."

Ford just announced 300 mile range, 99kWh battery for the Mach E.

Whatever the commercial opportunity for Bunched Pt-Ni alloy nanocages, batteries are going to be a hard act to beat for passenger cars.

SJC

Passenger cars are part of the fuel consumption,
trucks are a large part as well.

gryf

Very interestingTruck news from Nikola Motors about batteries not H2.
From the Nikola Motors web site Press Release:


  • World’s first free-standing electrode automotive battery

  • Energy density up to 1,100 watt-hours per kg on a material level and 500 watt-hours per kg on a production cell level including; casing, terminals and separator -- more than double current lithium-ion battery cells

  • Cycled over 2,000 times with acceptable end-of-life performance

  • 40% reduction in weight compared to lithium-ion cells

  • 50% material cost reduction per kWh compared to lithium-ion batteries


We must wait until 2020 to see if this is real.

gryf

Is the Nikola Motor Battery for real? Just a guess, there is a free-standing electrode battery that uses none of the Lithium Ion metals and could have up to 1,100 watt-hours per kg on a material level basis. Check out the "A free-standing reduced graphene oxide aerogel as supporting electrode in a fluorine-free Li2S8 catholyte Li-S battery."
Again we must wait until some time next year to see.

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