According to new research from Rice University, while Edison’s goal was simply to create a longer-lasting electric lamp, the extreme conditions created inside Edison’s carbon filament bulbs in those early light bulbs may have inadvertently produced the same conditions needed to create graphene.

The study by James Tour and his former graduate student Lucas Eddy, who was the lead researcher, shows that when the authors recreated Edison’s original incandescent light bulb, they also discovered that the same electrical heating caused by the filament could convert the carbon filament into turbostratic graphene, the name for a type of graphene with loosely stacked atomic layers.

Graphene is a single layer of carbon arranged in a two-dimensional honeycomb shape. It is incredibly strong, highly conductive, and transparent. While P.R. Wallace, a physicist in the 1940s, had proposed the theoretical existence of graphene, it was not until the early 2000s that graphene was isolated and characterized by Konstantin Novoselov and Andre Geim, who won the 2010 Nobel Prize in Physics for their work on graphene.

In his incandescent light bulbs, Edison used carbon filaments, usually made from the pyrolyzed remains of Japanese bamboo, enclosed in a sealed vacuum glass bulb. When the filament was heated by the flow of electricity through it, the electric current’s resistance caused it to heat to between 1,800 and 2,300 degrees Celsius. This produced a light source and allowed the filament to burn much longer than incandescent light bulbs of previous design. The procedure is an outstanding example of the evolution and improvement of the production of graphene.

“This is something I saw when trying to create a low-cost and easy method of producing graphene,” Eddy told us in his interview. “I had been developing multiple ways to produce graphene on a large scale using easily obtained and low-cost materials. The majority of my ideas included arc welders, which worked better than any method I’d previously built, and lightning-struck trees, which had no success.”

He explained how he arrived at this finding. “In order to discover what the simplest and most efficient way to create flash Joule heating would be, I began reviewing all sorts of objects. The first thing I thought of was that early light bulbs were made from carbon-based filaments.” Eddy also mentioned that light bulbs made with carbon-based filaments were manufactured in the early 1800s.

When trying to find authentic light bulbs, Eddy states, “I couldn’t find any authentic Edison-style light bulbs. All the replicas I found that said they were made from carbon filaments really used tungsten. Chemists are trained to identify materials that look like they are carbon but have completely different structures.” After a long search, he found light bulbs manufactured by artisans in New York City that were close to the originals produced by Edison, including bamboo filaments that were of near-identical dimensions.

To repeat an experiment that had taken place over 140 years ago, Eddy connected the light bulb to a 110-volt direct current power supply. He applied the voltage to the filament for 20 seconds to replicate Edison’s exact original process. He also cautioned against leaving the light bulb on for too long, noting that carbon would turn into graphite rather than graphene after prolonged heating.

The visual transformation of the filament was obvious. With the aid of an optical microscope, Eddy states that the filament’s structure clearly transformed from a dull gray color to shiny silver. This transformation indicated a substantial rearrangement of the structure of the carbon at the atomic level.

Eddy used Raman spectroscopy as a means of determining what had formed. This technique was invented in the early 1930s and is now widely used to investigate carbon materials. It allows an investigator to shine a laser beam onto a sample and measure how the light scatters off the sample, which reveals the atomic structure of the material. Results from the Raman analysis confirmed that some portions of the filament had converted into turbostratic graphene.

The conclusion that turbostratic graphene was formed by the filament upon heating was further supported through electrical analyses. These analyses showed that the filament’s resistance decreased by approximately 35 percent after heating had taken place. This clearly suggested there was an atomically based structural change, not simply thermal degradation of the filament. Physical measurement data showed there were only slight changes in diameter and no change in length, further supporting the idea of structural transformation at the atomic scale.

Present-day scientists used transmission electron microscopy to verify their findings. Prior to the heating process, the filament appeared to be relatively disordered. Following heating, however, well-defined layered structures were present, with the spacing between the layers characteristic of turbostratic graphene. There was also some amorphous carbon still remaining, but the existence of graphene layers cannot be ignored.

Taking all these pieces of evidence into account, including optical, electrical, spectroscopic, and microscopic data, a very strong conclusion can be drawn. The environment created by Thomas Edison when he invented the light bulb allowed for the creation of graphene, even though it would be more than one hundred years before graphene would be recognized as a separate substance.

“It is very exciting to be able to recreate what Thomas Edison was able to do, using the tools and materials we have available to us today,” Tour told The Brighter Side of News. “The revelation that graphene could have originated from Edison’s light bulbs opens up the possibility of becoming curious about what other information may be hidden within the historical context of experimentation. What would our predecessors who were scientists ask if they joined us in the laboratory today?”

It is impossible to determine if graphene was ever produced by Edison himself. The longest tests Edison’s laboratory conducted on the bulbs lasted a maximum of 13 hours. It is likely that the extremely short time required to generate sufficient heat was more than adequate to ensure that graphene formed and then converted into graphite over the years of testing. How the existence of graphene affects perceptions of early inventions illustrates the impact of modern scientific discoveries on history.

Edison is well known as a pioneer for creating a viable system for electric light. The fact that Edison may have been able to gather many of the fundamental day-to-day properties of carbon in his devices likely has not been fully appreciated. Many hundreds of patents were generated by Edison’s laboratories, and Edison’s light bulb functioned as a high-temperature, electric-powered reactor.

The results of this research support the idea that many other historical technologies were similarly developed with substantial underlying science that is not yet known. Historical devices such as arc lamps and X-ray machines operated under extreme conditions. They therefore represent an excellent opportunity for developing new technologies not previously understood. By analyzing these devices using current methods, perhaps new technologies will be discovered.

The excitement and challenge presented by the possibility that one of the most advanced materials in the 21st century may have originated in the 1800s is compelling. It provides a key to unlocking future opportunities. The ability to ask new questions about technologies that have long been accepted in daily life is essential to continued scientific advancement.

Based on the findings of this research, it is clear that carbon filament, Edison-style systems represent one of the easiest and most cost-effective methods to study the production of graphene. By using an Edison-style filament to heat carbon to very high temperatures and place it in an electric field, it is possible to create many structural forms of carbon under varying conditions of heat and electric field strength.

This research may enable researchers to further explore the properties of these carbon structures, as well as the mechanisms responsible for producing defects, stability, and phase transitions.

Overall, the work encourages scientists to continue evaluating historical experiments with modern analysis techniques to identify new opportunities for developing technologies, improving manufacturing methods, and more fully understanding how foundational inventions shaped modern science.

Research findings are available online in the journal ACS Nano.