期刊
NANOMATERIALS
卷 12, 期 11, 页码 -出版社
MDPI
DOI: 10.3390/nano12111939
关键词
supercapacitor; energy storage; coffee ground-derived biochar; graphene quantum dots (GQDs); erbium
类别
资金
- Ministry of Science and Technology (MOST), Taiwan
- MOST [108-2113-M-007-021-MY3, 110-2221-E-007-058-MY3]
In this study, a nanocomposite with erbium-doped graphene quantum dots embedded in highly porous coffee-ground-derived biochar (Er-GQD/HPB) was synthesized as an electrode material for a highly efficient supercapacitor. The addition of Er-GQDs significantly increased the specific capacitance and enhanced the cycling stability of the material.
A nanocomposite with erbium-doped graphene quantum dots embedded in highly porous coffee-ground-derived biochar (Er-GQD/HPB) was synthesized as a promising electrode material for a highly efficient supercapacitor. The HPB showed high porosity, with a large surface area of 1295 m(2) g(-1) and an average pore size of 2.8 nm. The 2-8-nanometer Er-GQD nanoparticles were uniformly decorated on the HPB, subsequently increasing its specific surface area and thermal stability. Furthermore, the intimate contact between the Er-GQDs and HPB significantly reduced the charge-transfer resistance and diffusion path, leading to the rapid migration of ions/electrons in the mesoporous channels of the HPB. By adding Er-GQDs, the specific capacitance was dramatically increased from 337 F g(-1) for the pure HPB to 699 F g(-1) for the Er-GQD/HPB at 1 A g(-1). The Ragone plot of the Er-GQD/HPB exhibited an ultrahigh energy density of 94.5 Wh kg(-1) and a power density of 1.3 kW kg(-1) at 1 A g(-1). Furthermore, the Er-GQD/HPB electrode displayed excellent cycling stability, and 81% of the initial capacitance remained after 5000 cycles. Our results provide further insights into a promising supercapacitance material that offers the benefits of both fast ion transport from highly porous carbons and electrocatalytic improvement due to the embedment of Er-doped GQDs to enhance energy density relative to conventional materials.
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