Keratin-Graphene Nanocomposite: Transformation of Waste Wool in Electronic Devices

Electronic devices, designed to be long lasting, are commonly made with rigid, nondegradable materials. These, together with the presence of rare and toxic elements, create significant issues for their waste management. The production of electronic devices, made with biodegradable materials that are sourced from waste streams of the agricultural sector, will create the premises for circular economy systems in the electronics sector that will increase their sustainability. Here, this new approach has been demonstrated by using keratin, the protein extracted from waste wool clips, combined with graphene to produce protein-based electronic materials. Resistors plane capacitors and inductors were fabricated, characterized, and then assembled together to obtain analogue electrical circuits such as high-pass filters or resonators. Morphological structures, electrical characteristics, thermal stability, and mechanical properties were fully investigated. Finally, a water-based ink of keratin and graphene was used to functionalize cellulose to obtain flexible electrodes with remarkable sheet resistances (≈10 ω/sq); ohmic I-V curves were obtained, and the electrical conductivity after folding/unfolding cycles was measured. All the processing and fabrication methods used water as the only solvent. The described approach produced easily disposable electronics materials with a reduced fingerprint on the environment, demonstrating that keratin from wool waste is an excellent candidate for the creation of circular economy systems in the electronics sector. The proposed valorization of waste materials for electronics applications is named "wastetronics".