Institute of Precision Electronic Components, College of Semiconductor and Advanced Technology Research, National Sun Yat-sen University, Kaohsiung 804201, Taiwan.
Int J Mol Sci. 2024 Oct 10;25(20):10884. doi: 10.3390/ijms252010884.
Hierarchical porous carbon derived from discarded biomass for energy storage materials has attracted increasing research attention due to its cost-effectiveness, ease of fabrication, environmental protection, and sustainability. Brewed tea leaves are rich in heteroatoms that are beneficial to capacitive energy storage behavior. Therefore, we synthesized high electrochemical performance carbon-based composites from Tie guan yin tea leaf waste using a facile procedure comprising hydrothermal, chemical activation, and calcination processes. In particular, potassium permanganate (KMnO) was incorporated into the potassium hydroxide (KOH) activation agent; therefore, during the activation process, KOH continued to erode the biomass precursor, producing abundant pores, and KMnO synchronously underwent a redox reaction to form MnO nanoparticles and anchor on the porous carbon through chemical bonding. MnO nanoparticles provided additional pseudocapacitive charge storage capabilities through redox reactions. The results show that the amount of MnO produced is proportional to the amount of KMnO incorporated. However, the specific surface area of the composite material decreases with the incorporated amount of KMnO due to the accumulation and aggregation of MnO nanoparticles, thereby even blocking some micropores. Optimization of MnO nanocrystal loading can promote the crystallinity and graphitization degree of carbonaceous materials. The specimen prepared with a weight ratio of KMnO to hydrochar of 0.02 exhibited a high capacitance of 337 F/g, an increase of 70%, owing to the synergistic effect between the Tie guan yin tea leaf-derived activated carbon and MnO nanoparticles. With this facile preparation method and the resulting high electrochemical performance, the development of manganese oxide/carbon composites derived from tea leaf biomass is expected to become a promising candidate as an energy storage material for supercapacitors.
基于废弃生物质的分级多孔碳由于其成本效益高、易于制造、环保和可持续性，在储能材料方面引起了越来越多的研究关注。泡过的茶叶富含有利于电容储能行为的杂原子。因此，我们采用水热、化学活化和煅烧工艺的简便程序，从铁观音茶废料中合成了具有高电化学性能的碳基复合材料。特别是，将高锰酸钾 (KMnO) 掺入到氢氧化钾 (KOH) 活化剂中；因此，在活化过程中，KOH 继续侵蚀生物质前体，产生丰富的孔，同时 KMnO 发生氧化还原反应，形成 MnO 纳米粒子并通过化学键锚定在多孔碳上。MnO 纳米粒子通过氧化还原反应提供额外的赝电容电荷存储能力。结果表明，MnO 的生成量与掺入的 KMnO 量成正比。然而，由于 MnO 纳米粒子的积累和聚集，复合材料的比表面积随着 KMnO 掺入量的增加而减小，从而甚至堵塞了一些微孔。MnO 纳米晶负载量的优化可以促进碳质材料的结晶度和石墨化程度。在 KMnO 与水热炭的重量比为 0.02 的条件下制备的样品表现出 337 F/g 的高电容，增加了 70%，这归因于铁观音茶衍生的活性炭和 MnO 纳米粒子之间的协同效应。由于这种简便的制备方法和由此产生的高电化学性能，预计基于茶叶生物质的氧化锰/碳复合材料的开发将成为超级电容器储能材料的有前途的候选材料。
