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

Shape-shifting sensors could catch early signs of cancer October 19th, 2018

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Iran Produces Cooling Fabrics Using Nanotechnology October 17th, 2018

Iran World’s Second Largest Producer of Nano-Catalysts October 17th, 2018

Iran Unveils Its First Homegrown 3D Nano Printer October 17th, 2018

Chemistry

Iran World’s Second Largest Producer of Nano-Catalysts October 17th, 2018

Big award enables study of small surfaces: Rice U.'s Matt Jones wins Packard Fellowship to view nanoscale chemical reactions October 15th, 2018

High-performance self-assembled catalyst for SOFC October 12th, 2018

Graphene/ Graphite

Researchers quickly harvest 2-D materials, bringing them closer to commercialization: Efficient method for making single-atom-thick, wafer-scale materials opens up opportunities in flexible electronics October 12th, 2018

Graphene shows unique potential to exceed bandwidth demands of future telecommunications October 12th, 2018

Graphene controls surface magnetism at room temperature October 8th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Shape-shifting sensors could catch early signs of cancer October 19th, 2018

Arrowhead Pharmaceuticals Files for Regulatory Clearance to Begin Phase 1 Study of ARO-ANG3 October 15th, 2018

Graphene shows unique potential to exceed bandwidth demands of future telecommunications October 12th, 2018

High-performance self-assembled catalyst for SOFC October 12th, 2018

Possible Futures

Shape-shifting sensors could catch early signs of cancer October 19th, 2018

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Iran Unveils Its First Homegrown 3D Nano Printer October 17th, 2018

Rice U. announces $82 million in strategic research initiatives: Faculty, programs will expand in neuroengineering, synthetic biology, physical biology October 16th, 2018

Discoveries

Shape-shifting sensors could catch early signs of cancer October 19th, 2018

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Researchers quickly harvest 2-D materials, bringing them closer to commercialization: Efficient method for making single-atom-thick, wafer-scale materials opens up opportunities in flexible electronics October 12th, 2018

Graphene shows unique potential to exceed bandwidth demands of future telecommunications October 12th, 2018

Materials/Metamaterials

Aculon, Inc. Enters into Strategic Partnership Agreement with Henkel Corporation to Supply Key Mobile Device Manufacturers with NanoProof® PCB Waterproof Technology October 17th, 2018

Big award enables study of small surfaces: Rice U.'s Matt Jones wins Packard Fellowship to view nanoscale chemical reactions October 15th, 2018

Graphene controls surface magnetism at room temperature October 8th, 2018

Unmasking corrosion to design better protective thin films for metals: Researchers from three universities team up to analyze oxide films at atomic level October 3rd, 2018

Announcements

Shape-shifting sensors could catch early signs of cancer October 19th, 2018

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Iran Unveils Its First Homegrown 3D Nano Printer October 17th, 2018

Fat-Repellent Nanolayers Can Make Oven Cleaning Easier October 17th, 2018

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

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Big award enables study of small surfaces: Rice U.'s Matt Jones wins Packard Fellowship to view nanoscale chemical reactions October 15th, 2018

Graphene shows unique potential to exceed bandwidth demands of future telecommunications October 12th, 2018

High-performance self-assembled catalyst for SOFC October 12th, 2018

Military

Columbia Engineers Build Smallest Integrated Kerr Frequency Comb Generator October 9th, 2018

Light makes Rice U. catalyst more effective: Halas lab details plasmonic effect that allows catalyst to work at lower energy October 5th, 2018

Unmasking corrosion to design better protective thin films for metals: Researchers from three universities team up to analyze oxide films at atomic level October 3rd, 2018

Ultracold atoms used to verify 1963 prediction about 1D electrons: Rice University, University of Geneva study focuses on theory that's increasingly relevant to chipmakers September 5th, 2018

Automotive/Transportation

Iran Unveils Its First Homegrown 3D Nano Printer October 17th, 2018

180 Degree Capital Corp. Announces New Portfolio Holdings – Airgain, Inc., EMCORE Corporation, Lantronix, Inc. and PDL BioPharma, Inc. October 12th, 2018

Columbia Engineers Build Smallest Integrated Kerr Frequency Comb Generator October 9th, 2018

A Comprehensive Guide: The Future of Nanotechnology September 13th, 2018

Fuel Cells

High-performance self-assembled catalyst for SOFC October 12th, 2018

Harvesting clean hydrogen fuel through artificial photosynthesis May 3rd, 2018

A new way to find better battery materials: Design principles could point to better electrolytes for next-generation lithium batteries March 29th, 2018

Study boosts hope for cheaper fuel cells: Rice University researchers show how to optimize nanomaterials for fuel-cell cathodes January 6th, 2018

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

Iran World’s Second Largest Producer of Nano-Catalysts October 17th, 2018

Big award enables study of small surfaces: Rice U.'s Matt Jones wins Packard Fellowship to view nanoscale chemical reactions October 15th, 2018

Tracking a Killer: UCSB, UCSD and SBP researchers trace the complex and variable pathways to the deadly condition known as sepsis October 12th, 2018

Columbia Engineers Build Smallest Integrated Kerr Frequency Comb Generator October 9th, 2018

Research partnerships

Tracking a Killer: UCSB, UCSD and SBP researchers trace the complex and variable pathways to the deadly condition known as sepsis October 12th, 2018

Columbia Engineers Build Smallest Integrated Kerr Frequency Comb Generator October 9th, 2018

Leti Announces EU Project to Develop Powerful, Inexpensive Sensors with Photonic Integrated Circuits: REDFINCH Members Initially Targeting Applications for Gas Detection and Analysis For Refineries & Petrochemical Industry and Protein Analysis for Dairy Industry September 19th, 2018

Researchers develop microbubble scrubber to destroy dangerous biofilms September 19th, 2018

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