Beyond chemical composition: how precursor genesis governs MoS₂exfoliation, dispersion, stability and thin-film...

Molybdenum disulfide (MoS₂) is a two-dimensional material with unique electronic, optical, and mechanical properties. However, these properties may vary significantly among samples of different origins. Here, we present a systematic comparative study of two MoS₂samples obtained from distinct sources: a laboratory-synthesized material (MoS₂-S) and a commercially available one (MoS₂-C). Using liquid-phase exfoliation in three pure solvents (acetonitrile, ethanol, and water) and two binary solvent mixtures (water/ethanol and water/acetonitrile, 1:1 v/v), we investigate how precursor genesis and solvent characteristics jointly govern exfoliation/fragmentation behavior, dispersion stability, and processability. Comprehensive characterization by UV-Vis and Raman spectroscopies, scanning electron microscopy, high-resolution transmission electron microscopy, and atomic force microscopy reveals pronounced sample-dependent differences. MoS₂-S consists of smaller, thinner flakes with abundant edge sites and structural defects, which favors a combined process of ultrasonic fragmentation, partial layer delamination, and colloidal stabilization, leading to highly concentrated and long-term stable dispersions. In contrast, MoS₂-C is composed of larger, highly crystalline flakes dominated by extended basal planes, which exhibit more resistance to both fragmentation and layer separation, resulting in lower dispersion yields and poor colloidal stability. Importantly, these differences persist beyond the dispersion stage. Selected solvents were employed to construct analytical calibration curves and to fabricate thin films with controlled loadings via a liquid-liquid interfacial route. A direct correlation is established between the quality of the initial dispersion and the homogeneity of the resulting films, demonstrating that precursor-controlled exfoliation behavior critically determines downstream processability. Overall, this work highlights precursor genesis as a key and often overlooked parameter in MoS₂processing, showing that materials with identical chemical composition can behave as fundamentally distinct systems when transformed frombulkpowders into dispersions and thin films.