Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International

Wikipedia Affiliate Button

Home > Press > Rice sleuths find metal in 'metal-free' catalysts: Study of graphene catalysts finds trace of manganese, suggests better ultrathin fuel-cell components

Three transmission electron microscope images of nitrogen-doped graphene show the relative presence of manganese atoms, contaminants from graphite precursors or reactants believed responsible for the material's ability to catalyze oxygen-reduction reactions, according to Rice University scientists. The top image shows many manganese atoms (white) remain on graphene that has been washed once; few on twice-washed graphene in the center image; and none on graphene washed six times at bottom. Twice-washed graphene with a scattering of manganese atoms proved best for catalysis. (Credit: Tour Group/Rice University)
Three transmission electron microscope images of nitrogen-doped graphene show the relative presence of manganese atoms, contaminants from graphite precursors or reactants believed responsible for the material's ability to catalyze oxygen-reduction reactions, according to Rice University scientists. The top image shows many manganese atoms (white) remain on graphene that has been washed once; few on twice-washed graphene in the center image; and none on graphene washed six times at bottom. Twice-washed graphene with a scattering of manganese atoms proved best for catalysis. (Credit: Tour Group/Rice University)

Abstract:
Detective work by Rice University chemists has defined a deception in graphene catalysts that, until now, has defied description.

Rice sleuths find metal in 'metal-free' catalysts: Study of graphene catalysts finds trace of manganese, suggests better ultrathin fuel-cell components

Houston, TX | Posted on February 26th, 2018

Graphene has been widely tested as a replacement for expensive platinum in applications like fuel cells, where the material catalyzes the oxygen reduction reaction (ORR) essential to turn chemical energy into electrical energy.

Because graphene, the atom-thick form of carbon, isn't naturally metallic, researchers have been baffled by its catalytic activity when used as a cathode.

Wonder no more, said Rice chemist James Tour and his crew, who have discovered that trace quantities of manganese contamination from graphite precursors or reactants hide in the graphene lattice. Under the right conditions, those metal bits activate the ORR. Tour said they also provide insight into how ultrathin catalysts like graphene can be improved.

The research appears in the journal Carbon.

Because the contrast between carbon and manganese atoms is so slight, trace atoms of the contaminants can't be seen with traditional characterization techniques like X-ray diffraction and X-ray photoelectron spectroscopy (XPS).

"Labs have reported 'metal-free' graphene catalysts, and the evidence they've gathered could easily be interpreted to show that," Tour said. "In fact, the tools they were using simply weren’t sensitive enough to show the manganese atoms."

A more sensitive tool, inductively coupled plasma mass spectrometry (ICP-MS), clearly saw the interlopers among samples made by the Rice lab.

Nitrogen-doped graphene test samples were reduced from graphene oxide and then acid-washed between one and six times. With each wash, the ICP-MS scan showed fewer manganese atoms and detected none in graphene samples washed six times. By the fifth wash, the catalytic activity totally changed and showed the former activity had been due to those residual metal atoms.

The lab reported no manganese atoms were observed in any of the same samples using conventional analytical tools, including XPS or transmission electron microscopy.

The researchers characterized the samples' ORR activity and found twice-washed nitrogen-graphene was most effective. These samples tended to incorporate single atoms of manganese into the graphene structure, which facilitated full reduction of oxygen through a four-electron process in which four electrons are transferred to oxygen atoms, usually from hydrogen.

"In a four-electron process, oxygen is reduced to water or hydroxide," said Rice graduate student Ruquan Ye, the paper's lead author. "However, peroxide is formed in a two-electron process, which results in a lower diffusion-limited current density and generates hazardous reactive oxygen species." Ye said that without metal, the ORR in graphene is far less efficient.

Tour said the results should lead to investigation of the role of trace metals in other materials thought to be metal-free.

"Single-atom catalysts can hide among graphene, and their activity is profound," he said. "So what has sometimes been attributed to the graphene was really the single metal buried into the graphene surface. Graphene is good in its own right, but in these cases, it was being made to look even better by these single metal-atom stowaways."

Co-authors are graduate students Luqing Wang and Yilun Li and Boris Yakobson, the Karl F. Hasselmann Professor of Materials Science and NanoEngineering and a professor of chemistry; Rubén Mendoza-Cruz of Rice and the University of Texas at San Antonio; Miguel José Yacamán of the University of Texas at San Antonio; and Juncai Dong, Peng-Fei An and Dongliang Chen of the Chinese Academy of Sciences, Beijing.

The research was supported by the Air Force Office of Scientific Research, the Office of Naval Research, the National Center for Research Resources, the National Science Foundation-Partnerships for Research and Education in Materials, the National Institutes of Health's National Institute on Minority Health and Health Disparities, the National Natural Science Foundation of China and the Jianlin Xie Foundation of the Institute of High Energy Physics, Chinese Academy of Science.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,970 undergraduates and 2,934 graduate students, Rice’s undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for quality of life and for lots of race/class interaction and No. 2 for happiest students by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to http://tinyurl.com/RiceUniversityoverview .

Follow Rice News and Media Relations via Twitter @RiceUNews

For more information, please click here

Contacts:
David Ruth
713-348-6327


Mike Williams
713-348-6728

Copyright © Rice 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

Read the paper at:

Tour Group:

Wiess School of Natural Sciences:

Related News Press

News and information

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

ULVAC Launches Revolutionary PZT Piezoelectric Thin-film Process Technology and HVM Solution for MEMS Sensors/Actuators: Enabling Reliable, High-quality Film Production for Next Generation Devices August 16th, 2019

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

Kavli Lectures: Innovation by evolution and harnessing the quantum mechanics of the hydrogen bond August 15th, 2019

Chemistry

Kavli Lectures: Innovation by evolution and harnessing the quantum mechanics of the hydrogen bond August 15th, 2019

Graphene/ Graphite

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

A modified device fabrication process achieves enhanced spin transport in graphene August 6th, 2019

Physicists make graphene discovery that could help develop superconductors: Rutgers-led research could reduce energy use, improve electronic devices August 1st, 2019

Oddball edge wins nanotube faceoff: Rice U. theory shows peculiar 'Janus' interface a common mechanism in carbon nanotube growth July 29th, 2019

Govt.-Legislation/Regulation/Funding/Policy

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

Possible Futures

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

ULVAC Launches Revolutionary PZT Piezoelectric Thin-film Process Technology and HVM Solution for MEMS Sensors/Actuators: Enabling Reliable, High-quality Film Production for Next Generation Devices August 16th, 2019

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

Probing the Origin of Alzheimer’s . . . with Transistors: Novel high-sensitivity detector could aid in early diagnosis August 15th, 2019

Discoveries

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

Probing the Origin of Alzheimer’s . . . with Transistors: Novel high-sensitivity detector could aid in early diagnosis August 15th, 2019

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

Materials/Metamaterials

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

A modified device fabrication process achieves enhanced spin transport in graphene August 6th, 2019

Rice lab produces simple fluorescent surfactants: Compounds show promise for use in medicine, manufacturing August 5th, 2019

Wood You Like Some Fresh Water? New treatment for wood makes a membrane to extract fresh water August 5th, 2019

Announcements

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

ULVAC Launches Revolutionary PZT Piezoelectric Thin-film Process Technology and HVM Solution for MEMS Sensors/Actuators: Enabling Reliable, High-quality Film Production for Next Generation Devices August 16th, 2019

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

Probing the Origin of Alzheimer’s . . . with Transistors: Novel high-sensitivity detector could aid in early diagnosis August 15th, 2019

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

Military

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

Sharp meets flat in tunable 2D material: Rice's new atom-flat compounds show promise for optoelectronics, advanced computing August 12th, 2019

Oddball edge wins nanotube faceoff: Rice U. theory shows peculiar 'Janus' interface a common mechanism in carbon nanotube growth July 29th, 2019

Automotive/Transportation

ULVAC Launches Revolutionary PZT Piezoelectric Thin-film Process Technology and HVM Solution for MEMS Sensors/Actuators: Enabling Reliable, High-quality Film Production for Next Generation Devices August 16th, 2019

Activity of fuel cell catalysts doubled: Modelling leads to the optimum size for platinum fuel cell catalysts July 5th, 2019

Good vibrations: Using piezoelectricity to ensure hydrogen sensor sensitivity May 24th, 2019

New Argonne coating could have big implications for lithium batteries May 14th, 2019

Fuel Cells

Activity of fuel cell catalysts doubled: Modelling leads to the optimum size for platinum fuel cell catalysts July 5th, 2019

Artificial photosynthesis transforms carbon dioxide into liquefiable fuels May 22nd, 2019

Current generation via quantum proton transfer February 1st, 2019

Researchers use jiggly Jell-O to make powerful new hydrogen fuel catalyst: The inexpensive new material can split water just as efficiently as costly platinum December 14th, 2018

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

Researchers embrace imperfection to improve biomolecule transport August 8th, 2019

RIT awarded NSF funding to conceptualize Quantum Photonic Institute: RIT will develop plan for open-access Quantum Foundry for quantum photonic circuits August 7th, 2019

Research partnerships

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

Nanoparticles’ movement reveals whether they can successfully target cancer: Targeting nanoparticles rotate faster and move across larger areas August 9th, 2019

Researchers embrace imperfection to improve biomolecule transport August 8th, 2019

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