Thomas Edison may have accidentally created graphene - 130 years before its "official" discovery

Thomas Edison's experiments with the first incandescent light bulbs in the late 19th century may have had an unexpected side effect: the formation of graphene, an ultra-thin and ultra-strong material that is now considered one of the key materials for modern electronics. This conclusion was reached by researchers from Rice University, who repeated the conditions of experiments in 1879 using modern methods of analysis.

The work was published in the journal ACS Nano.

Graphene is a layer of carbon atoms just one atom thick and has unique electrical and mechanical properties. One of its types, turbostratic graphene, can be formed by rapidly heating carbon-containing materials to temperatures on the order of 2000-3000 °C using an electric current. In modern science, this method is known as flash Joule heating.

As the researchers found out, exactly such conditions could occur in early Edison lamps. Unlike modern lamps with tungsten filaments, the first examples used carbon fibres, including those made from Japanese bamboo. When voltage was applied, the filament heated up dramatically - potentially to temperatures hot enough to rearrange the carbon structure.

To test the hypothesis, the team, led by chemist James Tour, recreated the lamp from drawings of Edison's 1879 patent. The researchers found rare "artisan" lamps with bamboo filaments as close to the original as possible. The filament was connected to a source of direct current voltage of 110 volts and heated for only about 20 seconds - longer heating, according to the authors, leads to the formation of graphite, not graphene.

After the experiment, the carbon filament changed colour from dark grey to a silvery sheen, indicating structural changes. For precise analysis, the scientists used Raman spectroscopy, a method that allows substances to be identified by their "atomic fingerprint". The results showed: in part of the thread really formed turbostratic graphene.

The authors emphasise that it is impossible to say with certainty whether the same thing happened in Edison's original experiments. Even if graphene did form, it likely turned into graphite during long tests of the lamps, which could run for hours at a time.

Nevertheless, the study demonstrates that classic experiments of the past can hide unexpected scientific effects that only become apparent when re-analysed using modern knowledge and tools. According to the authors, Edison's work is an example of how 19th-century technologies could inadvertently approach the materials of the future.