Electrolyte-Dependent Electrochemical Exfoliation of MoS2 Nanosheets and Its Impact on Nonlinear Optical Limiting

Electrochemical exfoliation is an efficient approach for producing MoS2 nanosheets, yet the correlation between exfoliation conditions, structural evolution, and nonlinear optical (NLO) properties remains insufficiently understood. In this work, MoS2 nanosheets were prepared using two representative electrolyte systems, acetonitrile/TPABr and aqueous Na2SO4, under controlled voltages. The results reveal distinct exfoliation mechanisms, where ion intercalation dominates in the nonaqueous system, while bubble-assisted processes prevail in the aqueous system. Structural and chemical analyses (Raman, XRD, EDS, and XPS) demonstrate that the nonaqueous system yields MoS2 with higher crystallinity and lower oxidation degree, whereas the aqueous system shows increased oxidation with the coexistence of Mo5+ and Mo6+ species. Correspondingly, enhanced nonlinear absorption and optical limiting performance are observed. A clear mechanism–structure–property relationship is established, highlighting the critical role of electrolyte environment and applied voltage in tailoring NLO responses. This work provides insights into the controlled preparation of MoS2 nanosheets for photonic and optoelectronic applications.