High Quality Graphene Production

• Graphene, a carbon-based chicken wire on an atomic scale, is a material with great expectations.
• This material offers a light, transparent, flexible, and electrically conducting single layer of graphite with an increase of substantially in the past years.
• Our CEM technology replaces traditional CVD and exfoliation techniques while offering an improvement of stability, performance, accuracy, and scalability.

One of the major hurdles to overcome is scaling up graphene production to an industrial level. As a result, it’s a challenge to manufacture large quantities of graphene of a good quality at a sufficiently low price. The University of Cordoba in Spain investigates the production of high-quality graphene. They wish to discover large scale production using an atmospheric pressure plasma-based technique. This university is a customer of Iberfluid Instruments S.A., a distributor of Bronkhorst in Spain. Therefore, in their research, they use devices from Bronkhorst.

Advanced Technique for High Quality Graphene Production

The University of Cordoba investigates the production of high-quality graphene powder. This technique uses a special microwave plasma torch with ethanol as the carbon source. Additionally, it uses argon as carrier gas. Ethanol vapor has to be generated in a controlled way. As a result of this set up, ethanol vapor flow is both accurate and stable. The system should be able to operate efficiently with respect to the amount of ethanol used. Also, it should be able to scale-up easily.

Benefits of Using a Controlled Evaporation Mixer for Graphene Production

• CEM replaces bubbler with better performance, stability and accuracy
• Scalability
• Efficient use of chemical compounds

How a CEM Works

A Controlled Evaporator Mixer system (CEM) generates a controlled flow of ethanol vapor. The ethanol vapor flows into the plasma where it is converts into graphene powder at atmospheric pressure. Argon acts as carrier gas for the ethanol vapor flow. As part of this vapor flow control system, a thermal Mass Flow Controller (EL-FLOW Select) controls the gas flow of argon.

Simultaneously, a liquid Mass Flow Controller (mini CORI-FLOW) controls the flow of ethanol. Finally, these devices connect to a CEM vaporizer and mixer. This CEM device is a temperature controller, mixing, and evaporation instrument. As a result, the vapor / gas mixture generates in the CEM unit.

Using a CEM to Produce High Quality Graphene

Iberfluid Instruments S.A. integrates the components of the CEM system into an in-house design single panel. Just before the liquid Mass Flow Controller, liquid ethanol is present in a small vessel that is pressurized with helium gas. Furthermore, the atmospheric microwave plasma technique for graphene powder production inside a glass reactor with quartz window uses a TIAGO torch as plasma generator and a SAIREM microwave generator.

Typically, a flow of argon gas (99.999% purity) of 1,000 ml/min is used. This is because earlier investigations at the university shows that this flow rate favors the formation of solid carbon from ethanol decomposition. An ethanol flow of 2 g/h is ideal and corresponds with 2 vol% ethanol in the vapor/gas mixture. In turn, higher concentrations would result in flame extinction.

Comparing CEM Technology to CVD and Exfoliation for Graphene Production

Using this setup, the quality of the resulting graphene is comparable to graphene production through traditional chemical vapor deposition (CVD) or newer graphite exfoliation techniques. However, the scale-up of the current plasma-based technique is rather easy. It only requires connecting several devices in series. The CEM based vaporization system can replace traditional bubblers, with better performance, stability, and accuracy.

The university claims that the technique they use is environmentally friendly because no metal catalysts are necessary to activate the graphene growth process. Furthermore, if ethanol derives from the fermentation of agricultural processes, one could consider it to be a “green” carbon source.

If you’d like to learn more, you can download the research paper from the University of Cordoba: Scalable graphene production from ethanol decomposition by microwave argon plasma torch.