Abstract: In this work, a cation exchange strategy is employed to convert sub-1 nm ZnS nanowires into sub-1 nm Ag2S nanowires with NIR absorption capability in N, N-dimethylformamide (DMF) solvent. The morphology, elemental composition, crystal structure, and optical properties of these products are systematically characterized using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis-NIR spectrophotometry (UV-Vis-NIR). Theoretical calculations are performed to comparatively investigate the influence of solvation effects on the preparation process of sub-1 nm Ag2S nanowires in different reaction systems (toluene/methanol mixed solvent vs. DMF solvent). Leveraging the unique NIR absorption characteristics of these sub-1 nm nanowires, they are employed as photoactive units to construct photoelectrochemical photodetectors (PEC PDs), and their photodetection performance is systematically evaluated. The results demonstrate that under 850 nm NIR light irradiation, the Ag2S sub-1 nm nanowire-based PEC PDs exhibit an on/off ratio of 7449, a responsivity of 120.1 mA/W, a specific detectivity of 5.91×1011 Jones, the rise time/decay time of 0.18/0.11 s and a response range from 2 μW/cm2 to 8 mW/cm2.

Key words: Near-infrared; photoelectrochemical, Photodetector, sub-1 nm, cation exchange method