(93h) Production of Hollow Carbon Microfibers upon Pyrolysis of Human Hair

Carbon is one of the most abundant materials in nature and has been widely used in diverse applications for many decades. Among various allotropes, such as diamond, graphite, coke, amorphous carbon, carbon nanotubes (CNTs), glassy carbon has received tremendous attention for various applications where its elegant physical properties such as high hardness, high electrical conductivity, low density, impermeability to gases, and high temperature resistance, are required. It has been widely applied as an electrode material for electrochemistry.

Herein, we present a novel method to fabricate glassy carbon microfibers from human hair wastes for electrochemical sensing. We demonstrate that the unique anatomy of human hair, composed of cuticle, cortex, and medulla, leads to long, hollow carbon structure upon pyrolysis at high temperature (900°C-1100°C) in an N₂atmosphere. At the elevated temperature, all the non-carbon elements are removed and only carbon remains.

The human hair, which we used as the carbon precursor, is an interesting waste material and has plenty of applications in industry and academic research. The coaxial structure of hair results in long hollow glassy carbon structures upon pyrolysis. The morphology of human hair samples before and after pyrolysis was characterized using scanning electron microscopy. The chemical composition of natural and pyrolyzed human hairs was also characterized using Raman spectroscopy and energy-dispersive X-ray spectroscopy. Screen printed carbon electrodes were modified with the hair-derived carbons and applied for electrochemical sensing of dopamine and ascorbic acid. The hair-derived carbons significantly improved the performance of the electrochemical sensors compared to the unmodified sensors. The presented method provides a simple, and inexpensive way to fabricate hollow carbon microfiber electrodes in various patterns.