Application of coal-based graphene quantum dots in supercapacitors

被引：0
|
作者：
Zhang Y. [1 ]
Zhang C. [1 ]
Sun Y. [1 ]
Zeng H. [1 ]
Jia J. [1 ]
Jiang Z. [1 ]
机构：
[1] College of Chemistry and Chemical Engineering, Henan Polytechnic University, Henan, Jiaozuo
来源：
Huagong Jinzhan/Chemical Industry and Engineering Progress | 2023年 / 42卷 / 08期
关键词：
activated carbon; activation; coal; graphene quantum dots; microstructure; supercapacitor;
D O I：
10.16085/j.issn.1000-6613.2022-1791
中图分类号：
学科分类号：
摘要：
In order to solve the problems of excessive use of potassium hydroxide (KOH) and unreasonable pore structure distribution in the preparation of coal-based activated carbon, Taxi anthracite was used as carbon source to oxidize graphene quantum dots by potassium ferrate and hydrogen peroxide, and then mixed with KOH to prepare coal-based graphene quantum dots activated carbon. The results showed that this method could reduce the amount of KOH (making the alkali-carbon ratio less than 1), and the activation mechanism of the alkali-carbon ratio to graphene quantum dots was similar to that of coal. When the amount of KOH was small (alkali-carbon ratio with 0.25), only pore-forming effect was observed. After increasing the dosage (alkali-carbon ratio with 0.5), KOH had not only the pore-forming effect, but also the pore-expanding effect. The excess KOH (alkali carbon ratio with 0.75) was mainly focus on pore-expanding effect. With the increase of alkali-carbon ratio, the specific surface area and total pore volume of activated carbon also increased, and the micropore rate gradually decreased, while the mesoporous rate and the average pore size increased. When the alkali-carbon ratio was 0.75, the activation effect was the best. The specific surface area of GQDAC-0.75 was 1207.3m2/g, the micropore rate was 39.5%, and the mesoporous rate was 51.8%. Thanks to its unique hierarchical pore structure of “macropore-mesopore-micropore”, GQDAC-0.75 showed the optimal electrochemical performance with specific capacitance of 243.6F/g at 0.5A/g current density. When the current density increased to 10A/g, the specific capacitance of GQDAC-0.75 was maintained at 202.2F/g. Even the current density continued to increase to 100A/g, the specific capacitance was still 179.5F/g, and the specific capacitance could remain 191.6F/g at the current density of 20A/g after 10000 cycles with a 98.1% retention rate, which indicated the excellent rate performance and cycle performance. © 2023 Chemical Industry Press. All rights reserved.
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页码：4340 / 4350
页数：10
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