Despite the extensive use of graphene-based materials in K-ion batteries, the effects of various edge morphologies of graphene on K atom adsorption and diffusion are unclear. In this study, the effects of K atom adsorption and diffusion on zigzag graphene nanoribbons (ZGNRs) with hydrogen (−H), ketone (=O), hydroxyl (−OH), and carboxyl (−COOH) terminal groups were investigated by density functional theory calculations. ZGNRs terminating with −H, =O and −COOH promote K atom adsorption, whereas those terminating with −OH suppress it. The −H, =O, −OH and −COOH terminations have a negligible effect on K atom diffusion in the inner region of ZGNRs. In the edge region, the diffusion barriers are nearly unchanged for −H and −OH terminations; however, they are increased for =O and −COOH terminations in the edge region compared to those in the inner region. All the terminal groups hinder K atom diffusion from the edge region toward the inner region. Our results suggest that −H termination enhances K atom adsorption and has a negligible effect on the diffusion barrier of K atom in the edge region. Therefore, the ZGNR with −H termination could be a promising candidate for K-ion batteries.

中文翻译：

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不同端基的锯齿形石墨烯纳米带上钾原子吸附扩散的密度泛函理论研究

尽管石墨烯基材料在钾离子电池中得到广泛应用，但石墨烯的各种边缘形态对钾原子吸附和扩散的影响尚不清楚。在这项研究中，通过密度研究了 K 原子吸附和扩散对具有氢 (-H)、酮 (=O)、羟基 (-OH) 和羧基 (-COOH) 末端基团的锯齿形石墨烯纳米带 (ZGNR) 的影响。泛函理论计算。以-H、=O 和-COOH 结尾的ZGNR 促进了K 原子的吸附，而以-OH 结尾的ZGNR 则抑制了它。-H、=O、-OH 和 -COOH 末端对 ZGNR 内部区域中的 K 原子扩散的影响可以忽略不计。在边缘区域，-H 和 -OH 终端的扩散势垒几乎没有变化；然而，与内部区域相比，边缘区域的 =O 和 -COOH 终端增加了。所有末端基团都阻碍 K 原子从边缘区域向内部区域扩散。我们的结果表明 -H 终止增强了 K 原子的吸附，并且对边缘区域中 K 原子的扩散势垒的影响可以忽略不计。因此，具有-H终止的ZGNR可能是K离子电池的有希望的候选者。