Toward Scalable Electrochemical Exfoliation of Molybdenum Disulfide Powder through an Accessible Electrode Design

• Published in: Small methods 2024-07, p.e2400298
• Main Authors: Wilson, Nicholas David, Ozhukil Valappil, Manila, Martin, Barbara Y, Siu, Teri, Pennings, Joel, Mackintosh, Mira, Almadhoun, Mahmoud N, Ouyang, Jianying, Graddage, Neil, Pope, Michael A
• Format: Article
• Language: English
• ISSN: 2366-9608; 2366-9608
• DOI: 10.1002/smtd.202400298

Cathodic electrochemical intercalation/exfoliation of transition metal dichalcogenides (TMDs) with bulky tetraalkylammonium-based cations is gaining popularity as it avoids the semiconducting (2H) to metallic (1T) phase transformation in TMDs like molybdenum disulfide (MoS ) and, generally, produces sheets with a larger aspect ratio - important for achieving conformal sheet-to-sheet contact in optoelectronic devices. Large single crystals are typically used as the precursor, but these are expensive, often inaccessible, and result in limited quantities of material. In this paper, a 3D-printable electrochemical cell capable of intercalating gram-scale quantities of commercially available TMD powders is presented. By incorporating a reference electrode in the cell and physically restraining the powder with a spring-loaded mechanism, the system can probe the intercalation electrochemistry, for example, determining the onset of intercalation to be near -2.5 V versus the ferrocene redox couple. While the extent of intercalation depends on precursor quantity and reaction time, a high yield of exfoliated product can be obtained exhibiting average aspect ratios as high as 49 ± 44 similar to values obtained by crystal intercalation. The intercalation and exfoliation of a wide variety of pelletized commercial powders including molybdenum diselenide (MoSe ), tungsten diselenide (WSe ), tungsten disulfide (WS ), and graphitic carbon nitride (gCN) are also demonstrated.