Controlled oxidation and morphological evolution of monolayer MoS2 via direct oxygen-induced chemical vapor deposition

O 2 flow regulates the etching behavior of monolayer MoS 2 during CVD growth. • Oxidative etching evolves from edge-preferred to spatially distributed morphology. • XPS, Raman, PL, and SEM analyses support oxygen-induced structural evolution. • This approach provides an alternative to conventional post-growth oxidation for modulating MoS 2 oxidation during formation. • This work clarifies oxygen-flow-dependent morphology modulation in monolayer MoS 2 . Controlled oxidation of monolayer MoS 2 is an effective route to tailor its optical, electronic and catalytic properties. However, conventional post-treatment oxidation treatments often suffer from poor controllability, nonuniform damage, and limited morphological precision. Here, we demonstrate a direct oxygen-induced chemical vapor deposition (CVD) growth strategy that enables controllable oxidation during synthesis by precisely tuning the oxygen (O 2 ) flow rate. By systematically varying the O 2 flow rate, a clear transition from edge-localized oxidation to more spatially distributed etching behavior is revealed. This evolution is comprehensively characterized through Raman spectroscopy, photoluminescence (PL) spectra, X‑ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and supported by density functional theory (DFT) calculations, which together elucidate the coupled changes in optical response and surface morphology during oxidation. The results highlight the competing roles of oxygen-induced defect passivation and oxidation-driven etching, and their spatial dependence across the monolayer MoS 2 . This growth-integrated oxidation approach provides a promising route for constructing well-defined oxidized MoS 2 structures, and could potentially be explored for controlled doping, morphology engineering, heterostructure construction, and related device applications. Controllable O 2 oxidation during CVD growth of monolayer MoS 2 enables tunable edge-to-spatial etching transition. Download: Download high-res image (169KB) Download: Download full-size image