Anhydrous Liquid-Phase Exfoliation of Pristine Electrochemically Active GeS Nanosheets

• Published in: Chemistry of materials Vol. 30; no. 7; pp. 2245 - 2250
• Main Authors: Lam, David, Chen, Kan-Sheng, Kang, Joohoon, Liu, Xiaolong, Hersam, Mark C
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 10.04.2018; American Chemical Society (ACS)
• Subjects: charge transport; ENERGY STORAGE; energy storage (including batteries and capacitors); ENGINEERING; materials and chemistry by design; MATERIALS SCIENCE; NANOSCIENCE AND NANOTECHNOLOGY; synthesis (novel materials)
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.7b04652

Germanium sulfide (GeS) is an emerging layered material with high promise in its two-dimensional (2D) exfoliated form for energy storage applications. While liquid-phase exfoliation (LPE) has been utilized for the low-cost, scalable production of related 2D materials, it has not yet been demonstrated for GeS nanosheets due to its chemical instability in ambient conditions. Here, GeS LPE is achieved in anhydrous N-methyl-2-pyrrolidone using a customized sealed-tip sonication system, yielding sub-10 nm thick GeS nanosheets that are structurally pristine with minimal chemical degradation as revealed by atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Lithium-ion battery anodes based on these high-quality GeS nanosheets possess superlative electrochemical performance including high cycling stability over 1000 cycles and high rate capability in excess of 10 A g–1. Overall, this work establishes a scalable LPE pathway for the production of pristine electrochemically active GeS nanosheets that are well-suited for high-power lithium-ion battery applications.