Fig. 1. Schematic representation of VSe2 NP and NS formation using the PLA and ultra-sonication-assisted chemical exfoliation.

Fig. 2. TEM images showing the successful formation of (a) laser-ablated NPs and (b) chemically exfoliated NSs. (c) HRTEM image showing the lattice spacing in the synthesized NSs. (d) SEM image of the drop-casted NS solution. (e) AFM measurement results showing the formation of single to a few layers of VSe2 and its thickness profile.

Fig. 3. XRD patterns of the VSe2 (a) rock, and produced (b) NP and (c) NS samples.

Fig. 4. (a) Absorption spectra of the synthesized colloidal NPs and NSs. The inset estimates the optical band gap of the samples. (b) The transition from 1T phase to 2H phase in IR radiated VSe2 samples.

Fig. 5. (a) Images of the NP and NS solutions before and after excitation with UV-incident light and (b) their PL spectra upon excitation with a 300 nm light. (c) The change of the emission spectra of the NS sample under different excitation wavelengths. (d) PL spectra change after irradiation with continuous light for 4 h. (e) The dependence of PL on the excitation light intensity at an excitation wavelength of 330 nm with different slit width values.

Fig. 6. Raman spectra of the VSe2 rock and prepared NS samples.

Fig. 7. V 2p-O 1s and Se 3d spectra of the VSe2 (a),(d) rock, and the prepared (b),(e) NP and (c),(f) NS samples. All spectra have been deconvoluted to multiple peaks.