Nitrogen-doped carbon based on peptides of hair as electrode materials for surpercapacitors

•Hair was directly carbonized by environmental and energy-saving methods.•Hair was utilized to prepare nitrogen-doped carbon materials for supercapacitor.•A new approache for preparing nitrogen-rich active carbon from biomass waste of hair-like precursor.•Hair-based carbon having a non-crystalline layered structure and excellent capacitive performance.