To a glass dish, add a few atoms of carbon, a dash of hydrogen, and a splash of iron. Microwave on high for around half a minute. Serve.
In a series of experiments, María Fernanda Veloz-Castillo and colleagues from Mexico and the United States used the humble microwave and basic chemical compounds to create a mixed “dish” of carbon nanotubes (CNTs) and carbon fibres (CFs)—some of the strongest, most versatile substances known to us.
The work was recently published in the Canadian Journal of Chemistry.
In an ever-changing world of dwindling resources and rising costs, scientists are constantly looking for simple, low-cost, and efficient ways to manufacture CNTs and CFs.
The substances are extremely durable and lightweight compared with conventional materials. For example, by some estimates, CNTs could potentially reduce the weights of airplanes and spacecrafts by around 30%. CNTs and CFs also have extraordinary mechanical, thermal, and electrical properties. Researchers anticipate using them for “smart” structures and textiles and more energy-efficient and longer-lasting fuel cells and batteries. In fact, the global CNTs market is expected to reach almost 15 billion US dollars in less than a decade.
Currently, production of CNTs and CFs is complex, time-consuming, and uses expensive raw materials.
Veloz-Castillo and her team have created a low-cost method that they report to be “green and sustainable”.
They combined graphite and ferrocene (a compound containing a mixture of iron, carbon, and hydrogen) under high temperatures inside a modified domestic microwave (the temperature control sensor was deactivated as the “cooking” temperature was approximately 820°C). The group obtained a substantial yield of CNTs in less than 30 seconds.
Graphite is often a material of choice to create CNTs. Graphite—essentially carbon atoms arranged in hexagonal sheets—is excellent at absorbing microwave radiation, where the heating is instantaneous and specific.
During the “cooking” process, graphite rapidly absorbs heat and quickly increases its temperature. The high heat separates ferrocene into individual iron and carbon atoms. Iron atoms help break down graphite into its individual carbon atoms, and eventually accelerate the formation of CNTs and CFs.
The researchers confirmed the formation of CNTs by directing a variety of high-intensity lasers at them. By studying how the lasers interacted with CNTs, Veloz-Castillo and her team could determine the texture, chemical composition, and structure of CNTs at very high and detailed resolutions.
The authors modestly conclude their paper: “The use of microwave heating for the preparation of inorganic nanostructures is an open field of research that remains to be explored.”
Yet, Veloz-Castillo and her team have taken the first steps towards giving the world a safe, low-cost, and sustainable way to prepare CNTs. All it took was placing a glass dish inside a microwave and looking inside.
Read the paper: Carbon nanotubes and carbon fibers in a flash: an easy and convenient preparation of carbon nanostructures using a conventional microwave in the Canadian Journal of Chemistry.
