Human hair-derived nitrogen and sulfur co-doped porous carbon materials for gas adsorption

Abstract

Human hair, a biowaste composed of protein, is converted into nitrogen and sulfur co-doped porous carbonaceous materials via a facile degradation and carbonization/activation process. The resulting carbon materials possess a large specific surface area value (2700 m² g⁻¹) as well as high nitrogen and sulfur content (around 8.0 and 4.0 wt%, respectively). The morphology, composition and porous structure of the obtained materials were thoroughly characterized using scanning and transmission electron microscopy, elemental analysis, nitrogen and carbon dioxide sorption analysis, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, etc. It is confirmed that both the degradation and the carbonization/activation procedures play important roles in the porous structure formation. Furthermore, these materials are proven to exhibit good performances in gas adsorption: carbon dioxide uptake (up to 24.0 wt%, at 273 K and 1.0 bar), methane adsorption (up to 3.04 wt%, at 273 K and 1.0 bar), and hydrogen adsorption (up to 2.03 wt%, at 77 K and 1.0 bar). The high gas adsorption capacities could be attributed to the microporous structure combined with the surface functionalities. In addition, we believe that this synthesis process offers a facile and effective way for transforming protein-containing biowastes into functionalized porous carbonaceous materials.