Laser-Made Graphene Enables Simple, Low-Cost Nanogenerato

Devices that convert the energy from footsteps, arm movements, and breathing into electricity could charge smart watches and wearables. But they are complicated and costly to make. Now a team has made flexible energy-scavenging devices by simply blasting organic materials with a laser to create graphene films. This should give hardy, affordable power generators that can be sewn onto clothes or embedded in shoe soles.

Triboelectric nanogenerators (TENGs) that convert motion into electric power have been studied for several years. They rely on the charge transfer between two different materials that are pressed or rubbed together. The surfaces build up oppositely charged ions, which generates an electric current when a wire connects the two surfaces.

A typical TENG consists of an electron-giving conductor—usually a metal–and an electron-grabbing dielectric polymer placed close to each other. An electrode placed on the polymer extracts current. Researchers used metal or carbon nanomaterials such as graphene as electrodes. But fabricating the electrodes requires costly, involved techniques like vacuum deposition or chemical vapor deposition.

Rice University chemist James Tour and his colleagues instead used a one-step method they have developed for making porous graphene foams on carbonaceous materials. They zap things like cloth, paper and food multiple times with infrared laser pulses. This rearranges the carbon atoms in the materials to form a foamy black layer made of nanoscale sheets of graphene. This thicker graphene is 100 times as conductive as its single-layer cousin, Tour says.

This article is reproduced with permission from C&EN (© American Chemical Society). The article was first published on June 21, 2019.