Protein-derived nitrogen-doped hierarchically porous carbon as electrode material for supercapacitors

This study aimed at developing supercapacitor electrode materials from textile industry waste, thereby mediating waste disposal problem through reuse. Through a simple two-step process, nitrogen-doped hierarchically porous carbons (NHPC) derived from sericin, a waste protein, were synthesized and used for electrochemical capacitors for the first time. The as-prepared NHPC with a specific surface area of 2723 m(2) g(-1) and a pore volume of 1.42 cm(3) g(-1) exhibited a high specific capacitance of 287 F g(-1) at the current density of 0.5 A g(-1), which was comparable or even higher than that of numerous porous carbon materials reported previously. With this electrode, about 93% of the initial capacitance (221 F g(-1)/5 A g(-1)) was retained after 10,000 cycles, demonstrating a good cyclic stability. Moreover, the specific capacitance of sericin-derived NHPC is also better than that of fibroin-derived porous carbon. This work not only developed an effective way to prepare high-performance supercapacitor electrode materials from the waste protein, but also provided a strategy for its disposal issue and contributed to the environmental improvement.