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

Abstract

AbstractCathodic 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 (MoS2) 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 (MoSe2), tungsten diselenide (WSe2), tungsten disulfide (WS2), and graphitic carbon nitride (gCN) are also demonstrated.