Heteroatom doped porous carbon sheets derived from protein-rich wheat gluten for supercapacitors: The synergistic effect of pore properties and heteroatom on the electrochemical performance in different electrolytes

Abstract

Developing high-performance biomass-derived carbons and understanding the relationship between their structures and performance are highly desired for carbon-based supercapacitors. Herein, a wheat gluten-derived carbon with porous sheet-like structure, high specific surface area, and oxygen- and nitrogen-based heteroatom groups is fabricated. Their pore properties and heteroatom doping amount are adjusted through controlling the activation temperature. In aqueous electrolyte there is a significant synergistic effect between pore properties and heteroatom amount on the electrochemical performance of the gluten-derived carbon; while their performance is mainly determined by their pore properties in ionic liquid electrolytes. Besides, whatever in the aqueous and ionic liquid electrolytes ion sieving effect also affects their capacitive performance. The gluten-derived carbon prepared at 700 °C with reasonable pore properties and heteroatom amount shows the highest specific capacitance of 350 F g−1 at 0.5 A g−1 in 6 mol L−1 KOH. But the gluten-derived carbon prepared at 800 °C with the highest specific surface area of 2724 m2 g−1 possesses a high specific capacitance of 197 F g−1 at 0.25 A g−1 in the ionic liquid electrolyte. This work can provide a guideline for optimizing the performance of biomass-derived carbons through matching their pore properties and heteroatom with different electrolytes.