As one of the most obvious and abundant (not to mention renewable) resources on the planet, wood has long been a vital material for construction and crafting — but it has its limitations. As a heavy, organic material, wood isn’t ideal for use in modern technology because it is an exceedingly inefficient conductor. Yet, it remains dramatically more available than other materials used in high tech; not everyone can get their hands on pure silicon, but it’s easy enough to find some spare wood.
Perhaps that’s why a new discovery and creation from Rice University is so startling and exciting. Using a laser from Universal Laser Systems, Inc., two researchers have managed to produce one of the most conductive materials known to humans — graphene — from a block of wood.
Unfortunately, the process of transmogrifying wood in graphene isn’t as easy as chopping down a tree with a laser pointer. First, the type of wood matters: Birch and oak both have loose cell walls that are ineffective at generating graphene’s rigid configuration. Pine, however, naturally has a cross-linked lignocellulose structure which creates graphene more easily than those woods with a lower lignin content.
Next, the air matters. Typically, a laser burns wood, creating charcoal. Because charcoal and graphene are not one in the same, researchers needed to prevent the combustion that naturally occurs when laser and wood meet. The solution was eliminating oxygen, which requires performing the test in a chamber with an inert atmosphere. Using either hydrogen or argon — both of which prevent lasers from burning wood — researchers were able to produce graphene.
When it comes to the laser, it seems a standard industrial model will do. In fact, having a laser with easily adjustable settings is ideal because the power of the laser seems to affect the quality of the graphene. After setting their ULS Inc. laser to 70 percent power, chemist James Tour and his team, led by graduate students Ruquan Ye and YieuChyan, were the first successfully created laser-induced graphene (LIG) from wood, identifying so-called P-LIG (the P stands for pine) on a laser-etched Rice University athletics logo.
To prove their graphene’s quality, the team then used the P-LIG to create supercapacitors for energy storage and electrodes for splitting water molecules into hydrogen and oxygen. For the latter experiment, the pair of electro-catalysts proved to be exceedingly durable and effective, and for the former project, the supercapacitors seemed to have usable performance metrics. The grad students have several more ideas for the P-LIG, including applications within renewable energy, but for now, the team is content with demonstrating the efficacy of P-LIG.
Previous research has created graphene in other ways, even using lasers. LIG has been created time and again by using the laser to heat the surface of polyimide, an inexpensive plastic, in the same atmosphere. However, not all polyimide produces LIG, and while polyimide might be cheap, it isn’t necessarily easy to obtain. Meanwhile, anyone anywhere can find a block of pine, and given an air-tight, inert room, anyone anywhere can make graphene.
The ability to make graphene cheaply and easily is advantageous for many reasons. Graphene is emerging as the most important material of the 21st century, as its structure allows it to be the strongest, lightest, most conductive material known. Already, graphene has been applied to electronic devices in touch screens, batteries, and integrated circuits, and every day researchers conceive of new uses for the seemingly miraculous substance. For example, efforts are currently being made to apply graphene to biological engineering, ultrafiltration, energy creation, and storage.
Graphene from wood is particularly valuable because it is a naturally occurring mineral, unlike many of the materials used in electronics. Every year, we produce more than 20 tons of e-waste, or trash from electronic devices such as mobile phones, printers, televisions, and home appliances. Whereas most e-waste produces toxic substances that poison the environment, P-LIG could conscionably be sent back the ground with its wood platform to biodegrade naturally.
Advancements in material science are not uncommon, but using natural resources to develop innovative materials is rare. The Rice University team deserves to be celebrated for this outstanding breakthrough.