Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > 'Unzipped' carbon nanotubes could help energize fuel cells and batteries, Stanford scientists say

This drawing shows the damaged outer wall of a carbon nanotube with nanosized graphene pieces (white patches), which facilitate the formation of catalytic sites made of iron (yellow) and nitrogen (red) atoms. The catalyst reduces oxygen to water.

Credit: Guosong Hong
This drawing shows the damaged outer wall of a carbon nanotube with nanosized graphene pieces (white patches), which facilitate the formation of catalytic sites made of iron (yellow) and nitrogen (red) atoms. The catalyst reduces oxygen to water.

Credit: Guosong Hong

Abstract:
Multi-walled carbon nanotubes riddled with defects and impurities on the outside could replace some of the expensive platinum catalysts used in fuel cells and metal-air batteries, according to scientists at Stanford University. Their findings are published in the May 27 online edition of the journal Nature Nanotechnology.

'Unzipped' carbon nanotubes could help energize fuel cells and batteries, Stanford scientists say

Stanford, CA | Posted on May 27th, 2012

"Platinum is very expensive and thus impractical for large-scale commercialization," said Hongjie Dai, a professor of chemistry at Stanford and co-author of the study. "Developing a low-cost alternative has been a major research goal for several decades."

Over the past five years, the price of platinum has ranged from just below $800 to more than $2,200 an ounce. Among the most promising, low-cost alternatives to platinum is the carbon nanotube - a rolled-up sheet of pure carbon, called graphene, that's one-atom thick and more than 10,000 times narrower a human hair. Carbon nanotubes and graphene are excellent conductors of electricity and relatively inexpensive to produce.

For the study, the Stanford team used multi-walled carbon nanotubes consisting of two or three concentric tubes nested together. The scientists showed that shredding the outer wall, while leaving the inner walls intact, enhances catalytic activity in nanotubes, yet does not interfere with their ability to conduct electricity.

"A typical carbon nanotube has few defects," said Yanguang Li, a postdoctoral fellow at Stanford and lead author of the study. "But defects are actually important to promote the formation of catalytic sites and to render the nanotube very active for catalytic reactions."

Unzipped

For the study, Li and his co-workers treated multi-walled nanotubes in a chemical solution. Microscopic analysis revealed that the treatment caused the outer nanotube to partially unzip and form nanosized graphene pieces that clung to the inner nanotube, which remained mostly intact.

"We found that adding a few iron and nitrogen impurities made the outer wall very active for catalytic reactions," Dai said. "But the inside maintained its integrity, providing a path for electrons to move around. You want the outside to be very active, but you still want to have good electrical conductivity. If you used a single-wall carbon nanotube you wouldn't have this advantage, because the damage on the wall would degrade the electrical property."

In fuel cells and metal-air batteries, platinum catalysts play a crucial role in speeding up the chemical reactions that convert hydrogen and oxygen to water. But the partially unzipped, multi-walled nanotubes might work just as well, Li added. "We found that the catalytic activity of the nanotubes is very close to platinum," he said. "This high activity and the stability of the design make them promising candidates for fuel cells."

The researchers recently sent samples of the experimental nanotube catalysts to fuel cell experts for testing. "Our goal is to produce a fuel cell with very high energy density that can last very long," Li said.

Multi-walled nanotubes could also have applications in metal-air batteries made of lithium or zinc.

"Lithium-air batteries are exciting because of their ultra-high theoretical energy density, which is more than 10 times higher than today's best lithium ion technology," Dai said. "But one of the stumbling blocks to development has been the lack of a high-performance, low-cost catalyst. Carbon nanotubes could be an excellent alternative to the platinum, palladium and other precious-metal catalysts now in use."

Controversial sites

The Stanford study might also have resolved a long-standing scientific controversy about the chemical structure of catalytic active sites where oxygen reactions occur. "One group of scientists believes that iron impurities are bonded to nitrogen at the active site," Li said. "Another group believes that iron contributes virtually nothing, except to promote active sites made entirely of nitrogen."

To address the controversy, the Stanford team enlisted scientists at Oak Ridge National Laboratory to conduct atomic-scale imaging and spectroscopy analysis of the nanotubes. The results showed clear, visual evidence of iron and nitrogen atoms in close proximity.

"For the first time, we were able to image individual atoms on this kind of catalyst," Dai said. "All of the images showed iron and nitrogen close together, suggesting that the two elements are bonded. This kind of imaging is possible, because the graphene pieces are just one-atom thick."

Dai noted that the iron impurities, which enhanced catalytic activity, actually came from metal seeds that were used to make the nanotubes and were not intentionally added by the scientists. The discovery of these accidental yet invaluable bits of iron offered the researchers an important lesson. "We learned that metal impurities in nanotubes must not be ignored," Dai said.

Other co-authors of the study are Hailiang Wang, Liming Xie and Yongye Liang of Stanford; Wu Zhou, Juan-Carlos Idrobo and Stephen J. Pennycook of Vanderbilt University and Oak Ridge National Laboratory; and Fei Wei of Tsinghua University.

This work was supported, in part, by a grant from the Precourt Institute for Energy at Stanford; Intel; Lawrence Berkeley and Oak Ridge national laboratories; the Department of Energy; and the National Science Foundation.

This article was written by Mark Shwartz of the Precourt Institute for Energy at Stanford University.

####

For more information, please click here

Contacts:
Mark Shwartz

650-723-9296

Copyright © Stanford University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Dai Lab:

Related News Press

News and information

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Gene therapy relieves back pain, repairs damaged disc in mice: Study suggests nanocarriers loaded with DNA could replace opioids May 17th, 2024

Shedding light on perovskite hydrides using a new deposition technique: Researchers develop a methodology to grow single-crystal perovskite hydrides, enabling accurate hydride conductivity measurements May 17th, 2024

Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in cuprate superconductor May 17th, 2024

Imaging

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

First direct imaging of small noble gas clusters at room temperature: Novel opportunities in quantum technology and condensed matter physics opened by noble gas atoms confined between graphene layers January 12th, 2024

Laboratories

A battery’s hopping ions remember where they’ve been: Seen in atomic detail, the seemingly smooth flow of ions through a battery’s electrolyte is surprisingly complicated February 16th, 2024

NRL discovers two-dimensional waveguides February 16th, 2024

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

Govt.-Legislation/Regulation/Funding/Policy

International research team uses wavefunction matching to solve quantum many-body problems: New approach makes calculations with realistic interactions possible May 17th, 2024

Aston University researcher receives £1 million grant to revolutionize miniature optical devices May 17th, 2024

NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024

Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024

Nanotubes/Buckyballs/Fullerenes/Nanorods/Nanostrings

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

TU Delft researchers discover new ultra strong material for microchip sensors: A material that doesn't just rival the strength of diamonds and graphene, but boasts a yield strength 10 times greater than Kevlar, renowned for its use in bulletproof vests November 3rd, 2023

Tests find no free-standing nanotubes released from tire tread wear September 8th, 2023

Detection of bacteria and viruses with fluorescent nanotubes July 21st, 2023

Discoveries

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Finding quantum order in chaos May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

Announcements

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Finding quantum order in chaos May 17th, 2024

Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in cuprate superconductor May 17th, 2024

Tools

First direct imaging of small noble gas clusters at room temperature: Novel opportunities in quantum technology and condensed matter physics opened by noble gas atoms confined between graphene layers January 12th, 2024

New laser setup probes metamaterial structures with ultrafast pulses: The technique could speed up the development of acoustic lenses, impact-resistant films, and other futuristic materials November 17th, 2023

Ferroelectrically modulate the Fermi level of graphene oxide to enhance SERS response November 3rd, 2023

The USTC realizes In situ electron paramagnetic resonance spectroscopy using single nanodiamond sensors November 3rd, 2023

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Discovery of new Li ion conductor unlocks new direction for sustainable batteries: University of Liverpool researchers have discovered a new solid material that rapidly conducts lithium ions February 16th, 2024

A battery’s hopping ions remember where they’ve been: Seen in atomic detail, the seemingly smooth flow of ions through a battery’s electrolyte is surprisingly complicated February 16th, 2024

Fuel Cells

Current and Future Developments in Nanomaterials and Carbon Nanotubes: Applications of Nanomaterials in Energy Storage and Electronics October 28th, 2022

The “dense” potential of nanostructured superconductors: Scientists use unconventional spark plasma sintering method to prepare highly dense superconducting bulk magnesium diboride with a high current density October 7th, 2022

New iron catalyst could – finally! – make hydrogen fuel cells affordable: Study shows the low-cost catalyst can be a viable alternative to platinum that has stymied commercialization of the eco-friendly fuel for decades because it’s so expensive July 8th, 2022

Development of high-durability single-atomic catalyst using industrial humidifier: Identification of the operating mechanism of cobalt-based single-atomic catalyst and development of a mass production process. Utilization for catalyst development in various fields including fuel May 13th, 2022

Research partnerships

Gene therapy relieves back pain, repairs damaged disc in mice: Study suggests nanocarriers loaded with DNA could replace opioids May 17th, 2024

Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project