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Chemists create 3-D printed graphene foam

Nanotechnologists from Rice University and China’s Tianjin University have used 3-D laser printing to fabricate centimeter-sized objects of atomically thin graphene.

The research could yield industrially useful quantities of bulk graphene and is described online in a new study in the American Chemical Society journal ACS Nano.

Nanotechnologists from Rice University and China’s Tianjin University have used 3-D laser printing to fabricate centimeter-sized objects of atomically thin graphene.

Scanning electron microscope (left) and transmission electron microscope (right) images of 3-D printed graphene foam. The inset (right) is a selected area defraction pattern used to confirm that the material is graphene. Image credit: Yilun Li/Rice University

The research could yield industrially useful quantities of bulk graphene and is described online in a new study in the American Chemical Society journal ACS Nano.

In the latest study, a team from Tour’s lab and the labs of Rice’s Jun Luo and Tianjin’s Naiqin Zhao adapted a common 3-D selective laser sintering technique to make fingertip-size blocks of graphene foam. The process is conducted at room temperature. No molds are required and the starting materials are powdered sugar and nickel powder.

“This simple and efficient method does away with the need for both cold-press molds and high-temperature CVD treatment,” said co-lead author Junwei Sha, a former visiting student in Tour’s lab who is now a graduate student at Tianjin. “We should also be able to use this process to produce specific types of graphene foam like 3-D printed rebar graphene as well as both nitrogen- and sulfur-doped graphene foam by changing the precursor powders.”

3-D graphene foam objects are produced by shining a laser on a mixture of powdered sugar and nickel powder. The laser is moved back and forth to melt sugar in a 2-D pattern, and nickel acts as a catalyst to spur the growth of graphene foam. The process is repeated with successive layers of powder to build up 3-D objects. Image credit: Tour Group/Rice University

Three-D laser printers work differently than the more familiar extrusion-based 3-D printers, which create objects by squeezing melted plastic through a needle as they trace out two-dimensional patterns. In 3-D selective laser sintering, a laser shines down onto a flat bed of powder. Wherever the laser touches powder, it melts or sinters the powder into a solid form. The laser is rastered, or moved back and forth, line by line to create a single two-dimensional slice of a larger object. Then a new layer of powder is laid over the top of that layer and the process is repeated to build up three-dimensional objects from successive two-dimensional layers.

The new Rice process used a commercially available CO2 laser. When this laser was shone onto the sugar and nickel powder, the sugar was decomposed into carbon source and the nickel acted as a catalyst. Graphene formed as the mixture cooled after the laser had moved on to the next spot, and Sha and colleagues conducted an exhaustive study to find the optimal amount of time and laser power to maximize graphene production.

The foam created by the process is a low-density, 3-D form of graphene with large pores that account for more than 99 percent of its volume.

“The 3-D graphene foams prepared by our method show promise for applications that require rapid prototyping and manufacturing of 3-D carbon materials, including energy storage, damping and sound absorption,” said co-lead author Yilun Li, a graduate student at Rice.

Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice.

Additional co-authors include Rodrigo Villegas Salvatierra, Tuo Wang, Pei Dong, Yongsung Ji, Seoung-Ki Lee, Chenhao Zhang, Jibo Zhang and Pulickel Ajayan, all of Rice, and Robert Smith of Qualified Rapid Products in West Jordan, Utah.

The research was supported by the Air Force Office of Scientific Research and its Multidisciplinary University Research Initiative, the China Scholarship Council, the State Key Program of National Natural Science of China, the National Natural Science Foundation of China, the Special Foundation for Science and Technology Major Program of Tianjin and Universal Laser Systems.

Source: Rice University

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