For graphite pellets, just add elbow grease

It's easy and economical to make shiny pellets of graphite from functionalized graphene, according to scientists at Rice University.

A report in Carbon shows how chemically altered graphene powder can be pressed into a lightweight, semiporous solid that retains many of the strong and conductive qualities of graphite, the form of carbon found in pencils, lubricants and many other products that normally requires high-temperature processing to make.

Mohamad Kabbani, a former graduate student of Rice materials scientist Pulickel Ajayan and lead author of the paper, demonstrated the environmentally friendly, scalable process can be done in minutes by hand by grinding chemically modified graphene into a powder and using a hand-powered press to squeeze the powder into a solid pellet.

Kabbani previously showed how carbon nanotubes could be turned into graphene with a mortar and pestle rather than harsh chemicals. This time, he and his colleagues demonstrated how to make a battery-sized pellet, but the graphene powders with chemical functionalities attached to it can be pressed into any form. Kabbani said the material could be suitable for structural, catalytic, electrochemical and electronic applications.

"This is the first time anyone's made these at room temperature and without very high pressure," he said. "Usually these kind of materials require sintering (a process that uses pressure or heat to form solids without melting them) at temperatures above 1,000 degrees Celsius to produce strong pellets. In this case, mechano-chemistry at the nanoscale saved us a lot of energy and money."

The process began with two sets of functionalized nanotubes, one with carboxylic acid and the other with hydroxyl molecules. Once crushed to combine them either by hand or machine, they are placed in a lab-scale hydraulic press and subjected to 5 tons of pressure.

The functional groups cross-linked the graphene sheets to each other, and even though no liquids were involved, they produced a tiny amount of water as a byproduct of the reaction, Kabbani said.

The pellets remained stable when placed in hot water for five hours, even when stirred; this confirmed the interlocking of the graphene sheets within, the researchers reported.

The combination of light weight, high strength and high conductivity is appealing for applications such as conducting cables and electrodes, Kabbani said. "The pellet material is stronger and lighter than commercial graphite electrodes and could be promising for electrical storage applications with high energy and power densities," he said.

Research paper

Related Links
Rice University
Carbon Worlds - where graphite, diamond, amorphous, fullerenes meet

Tweet

Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

Ultrashort laser pulses make greenhouse gas reactive
Bonn, Germany (SPX) Mar 20, 2018
It is a long-cherished dream: Removing the inert greenhouse gas carbon dioxide from the atmosphere and using it as a basic material for the chemical industry. This could address two major problems at once by containing climate change and at the same time reducing the dependence on oil. Physico-chemists at the University of Bonn are in the process of making significant contributions to this vision. They have discovered a new way to create a highly reactive form of carbon dioxide with the help of la ... read more