The triboelectric effect is the phenomenon that causes, e.g., hair to be electrically charged after rubbing it with a balloon. Triboelectric nanogenerators based on this effect could be used to convert waste mechanical energy into usable electrical energy. They are, for example, a promising technology for self-sustainable energy harvesters in wearable electronic devices.

James M. Tour, Rice University, Houston, TX, USA, and colleagues have developed a triboelectric nanogenerator based on a laser-induced graphene (LIG) composite. To produce the composite, the team used infrared laser radiation to convert the carbon on the surface of either polyimide (PI) or cork into graphene. This gives composite, two-layered films. The LIG layer provides a high electrical conductivity and the cork or PI layer provides the necessary triboelectric properties. The LIG/PI composite performes particularly well as a nanogenerator.

The researchers then built LIG/PI triboelectric nanogenerators on an aluminium base and metal-free LIG/PI nanogenerators. They also created nanogenerators based only on LIG, which was embedded in polydimethylsulfoxide (PDMS). The LIG/PI/Al and the metal-free LIG/PI nanogenerators had an open circuit voltage of more than 3.5 kV and a peak power of more than 8 mW. The LIG/PDMS nanogenerator was found to be highly flexible and stretchable. It can generate power through mechanical contact with the skin, for example, as the sole of a flip-flop.

• Laser-Induced Graphene Triboelectric Nanogenerators,
  Michael G. Stanford, John T. Li, Yieu Chyan, Zhe Wang, Winston Wang, James M. Tour,
  ACS Nano 2019.
  https://doi.org/10.1021/acsnano.9b02596