Hydrothermal Phase Engineering of 1T/2H MoS <sub>2</sub> /Graphene Nanocomposites for Enhanced Electronic, Catalytic, and Electrochemical Performance
Le Ngoc Long, Tran Thi Ngoc Bich
Abstract
Abstract This work presents a comprehensive investigation into the phase engineering and interfacial reconstruction of 2D MoS 2 /graphene nanocomposites synthesized via hydrothermal treatment at 170–250 °C. A key innovation lies in the controlled modulation of the 1T/2H‐MoS 2 phase ratio, wherein low‐temperature synthesis enables stabilization of the highly conductive 1T phase, while elevated temperatures promote a transition to the semiconducting 2H phase. Simultaneously, defect‐laden graphene oxide is progressively restored to an sp 2 ‐hybridized network, facilitated by MoS 2 ‐mediated electron transfer and sulfur‐assisted reduction. Raman spectroscopy reveals a significant I D / I G ratio decline (from ≈1.28 to ≈0.07) and increased lateral crystallite size (≈15.0 to 260.6 nm), indicating enhanced graphitization. XPS and XRD investigation indicates a temperature‐induced 1T‐to‐2H MoS 2 phase transition, with Mo 3 d (Mo 3 d 5/2 /Mo 3 d 3/2 ) peaks shifting from ≈228.4/231.7 eV (1T phase) to ≈229.1/232.3 eV (2H phase), along with deoxygenation and reduced surface functionalization. HRTEM visualizes the emergence of coherent 2H‐MoS 2 nanodomains. Electrochemical analysis reveals a dramatic enhancement in conductivity (≈2.1 × 10 −3 S m −1 ) and capacitance (≈567.6 F cm −2 ), driven by optimized phase composition and interfacial synergy. These findings underscore the pivotal role of synthesis temperature in tailoring mixed‐phase architectures and interfacial chemistry, offering a tunable platform for next‐generation optoelectronic devices, energy storage, catalysis, and membrane technologies.