Hydrothermal Synthesis and Nanoscale Characterization of Single-Unit-Cell Bi₂WO₆ Nanosheets: Correlation between...

Single-unit-cell (SUC) Bi₂WO₆ nanosheets were successfully synthesized via a hydrothermal route and investigated through a comprehensive nanoscale characterization. Structural analyses by powder X-ray diffraction, Raman spectroscopy, and transmission electron microscopy confirmed the formation of a polycrystalline two-dimensional material. Atomic force microscopy revealed uniform nanosheets with an average thickness of ∼1.42 nm, consistent with a single-unit-cell configuration. Nanoscale mechanical analysis demonstrated that increasing PeakForce (1-5 nN) induces irreversible deformation of pre-existing surface pores, while higher oscillation frequencies (2-4 kHz) promote additional topographic modifications, indicating a frequency-dependent surface stability. Kelvin probe force microscopy (KPFM) mapping revealed a pronounced spatial variation in surface potential, with a lower work function at the nanosheet center and higher values at the edges. This edge-center electronic contrast establishes a direct correlation between morphology, adhesion behavior, and local surface potential, providing new insights into charge distribution in SUC-Bi₂WO₆. These findings highlight the relevance of nanoscale heterogeneity in governing surface reactivity, reinforcing the potential of Bi₂WO₆ nanosheets for applications in photocatalysis and nanoelectronics.