Abstract

How to modify carbon materials in a highly efficient manner is an important issue for the practical application. In this work, we demonstrate a hydrothermal approach for modifying nanoporous carbon using H₂O₂ and H₂SO₄ as oxygen/sulfur dopants, which can realize the purpose of achieving highly O/S doping. It reveals that hydrothermal temperature and dosage of H₂SO₄ exert crucial roles for determining the carbon structures and capacitive performances. The change of temperature affects the reaction process, changes the degree of oxidation of carbon by H₂O₂, and changes the number of oxygen-containing functional groups on carbon surface. Under constant temperature conditions, H₂SO₄, as a strong oxidizing acid, changes in its dosage will affect the oxidation strength of the system, while changing the number of oxygen-containing functional groups, increasing a certain amount of sulfur-containing functional groups. The specific capacitance of microporous carbon increases from 43 to 168 F g⁻¹, nearly 3.5 times, at a scan rate of 100 mV s⁻¹ in 6 M KOH aqueous electrolyte, under the action of oxygen-containing functional groups, and the cycle stability is also as high as 92%, which is higher than 90% of untreated nanoporous carbon. The energy density of the modified sample is 5.49 Wh kg⁻¹ at the power density of 0.5 kW kg⁻¹. In addition to improving the wettability of carbon materials, oxygen-containing functional groups also produce pseudocapacitance by redox reaction.

中文翻译：

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超级电容器在水热条件下对纳米多孔碳的低温高效氧/硫双重改性

摘要

如何以高效的方式改性碳材料是实际应用中的重要问题。在这项工作中，我们演示了使用H ₂ O ₂和H ₂ SO ₄作为氧/硫掺杂剂修饰纳米孔碳的水热方法，可以实现实现高O / S掺杂的目的。结果表明，水热温度和H ₂ SO _4的用量对决定碳的结构和电容性能起着至关重要的作用。温度的变化影响反应过程，改变H ₂ O ₂对碳的氧化程度，并更改碳表面上含氧官能团的数量。在恒温条件下，H ₂ SO ₄作为强氧化性酸，其剂量的变化会影响体系的氧化强度，同时改变含氧官能团的数量，增加一定量的含硫官能团。在含氧官能团的作用下，在100 MV s ^-1的扫描速率下，在6 M KOH水性电解质中，微孔碳的比电容从43 Fg ^-1增加到168 F g ^-1，几乎是3.5倍。稳定性也高达92％，高于未处理的纳米多孔碳的90％。改性样品的能量密度为5.49 Wh kg^-1在0.5千瓦公斤的功率密度^-1。除提高碳材料的润湿性外，含氧官能团还通过氧化还原反应产生假电容。