Waste coffee grounds-derived nanoporous carbon nanosheets for supercapacitors

초록

The development of nanostructured functional materials derived from biomass and/or waste is of growing importance for creating sustainable energy-storage systems. In this study, nanoporous carbonaceous materials containing numerous heteroatoms were fabricated from waste coffee grounds using a top-down process via simple heating with KOH. The nanoporous carbon nanosheets exhibited notable material properties such as high specific surface area (1960.1 m(2) g(-1)), numerous redox-active heteroatoms (16.1 at% oxygen, 2.7 at% nitrogen, and 1.6 at% sulfur), and high aspect ratios (> 100). These unique properties led to good electrochemical performance as supercapacitor electrodes. A specific capacitance of similar to 438.5 F g(-1) was achieved at a scan rate of 2 mV s(-1), and a capacitance of 176 F g(-1) was maintained at a fast scan rate of 100 mV s(-1). Furthermore, cyclic stability was achieved for over 2000 cycles.

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