Exfoliation of MoS<sub>2</sub> Nanosheets Enabled by a Redox-Potential-Matched Chemical Lithiation Reaction.

Zhu, Xiaolong; Su, Zipei; Wu, Chen; Cong, Hengjiang; Ai, Xinping; Yang, Hanxi; Qian, Jiangfeng · Nano Lett · 2022

basic_science · Level V

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Abstract

Ion intercalation assisted exfoliation is the oldest and most popular method for the scalable synthesis of molybdenum disulfide (MoS<sub>2</sub>) nanosheets. The commonly used organolithium reagents for Li<sup>+</sup> intercalation are <i>n</i>-butyllithium (<i>n</i>-BuLi) and naphthalenide lithium (Nap-Li); however, the highly pyrophoric nature of <i>n</i>-BuLi and the overly reducing power of Nap-Li hinder their extensive application. Here, a novel organolithium reagent, pyrene lithium (Py-Li), which has intrinsic safe properties and a well-matched redox potential, is reported for the intercalation and exfoliation of MoS<sub>2</sub>. The redox potential of Py-Li (0.86 V vs Li<sup>+</sup>/Li) is located just between the intercalation (1.13 V) and decomposition (0.55 V) potentials of bulk MoS<sub>2</sub>, thus allowing precise Li<sup>+</sup> intercalation to form a lamellar LiMoS<sub>2</sub> compound without undesirable structural damage. The lithiation reaction can be accomplished within 1 h at room temperature and the exfoliated nanosheets are almost single layer. This method also offers the advantages of low cost, high repeatability, and ease in realizing large-scale production.