首页|Molten-state cubic cage-templated uniform C3N4 hollow nanocubes and improved electrochemical performance of asymmetric micro-supercapacitor
Molten-state cubic cage-templated uniform C3N4 hollow nanocubes and improved electrochemical performance of asymmetric micro-supercapacitor
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NSTL
Elsevier
? 2022 Elsevier B.V.Controllable synthesis of hollow structure still remains a huge challenge. g-C3N4 hollow nanocubes with (002) facets exposed (c-CN) are for the first time prepared by calcining cyanuric acid-melamine in the presence of KCl. It is proposed that the c-CN growth is templated by cubic-phase KCl cage at molten state, then Oswald ripening leads to the hollowing of nanocubes. Moreover, silver is loaded on c-CN and its electrochemistry properties are investigated. It is found that at 0.05 mA/cm2, Ag/c-CN electrode shows a higher specific capacitance (10.44 mF/cm2) than that (3.79 mF/cm2) of Ag/p-CN (Ag loading on particle-like g-C3N4). The higher capacitance of Ag/c-CN is mainly attributed to the unique hollow nanocube morphology. On the one hand, c-CN has a larger BET surface area (19.8 m2/g) and a smaller electrical resistance (121.4 Ω), compared to p-CN (4.4 m2/g, 530.8 Ω). On the other hand, theory calculation indicates that the electrolyte cation (e.g., Na+, K+) is easier to desorb from (002) facet than from (100) facet. Hence, the exposed (002) facet of c-CN benefits the cation desorption, improving charging-discharging kinetic processes. Furthermore, after 2500 cycles, ~100% capacitance of Ag/c-CN is retained. It is proposed that the internal and external surfaces of hollow nanocubes can provide more accommodation sites for Ag, favoring the uniform distribution of Ag. Therefore, Ag/c-CN exhibits excellent electrochemical capacitance and cycle stability. Additionally, Ag/c-CN@CF//AC@CF asymmetric supercapacitor (ASC) displays a high energy density of 25 μWh/cm3, a high power density of 17 mW/cm3, and a long cycling lifetime (86.1% capacitance retention after 2500 charge/discharge cycles). The ASC is flexible and can be embedded into other power supply devices.
Jiangsu Engineering and Technology Research Centre of Environmental Cleaning Materials (ECM) Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC) Jiangsu Collaborative Innovation Centre of Atmospheric Environment and
NSTL
Elsevier
