Fabrication of 2D SnS₂ nanoflake photoanodes by a two-step process

Two-dimensional (2D) semiconductor thin films can potentially be applied in photoelectrochemical (PEC) water splitting owing to the layered structure and strong interaction with light. Herein, a vertically aligned 2D SnS₂ nanoflake photoanodes were synthesized by sulfurizing chemically deposited cubic SnS films on ITO-coated glass substrates at 350 ^∘C for different durations (10 to 60 min). Structural analysis revealed the formation of phase-pure crystalline SnS₂ films with a hexagonal structure. XPS analysis revealed the valence state of Sn and S to be +4, and -2, respectively. Morphological studies revealed the formation of 2D nanoflakes that are aligned vertically on the ITO substrate. Upon increasing the sulfurization time, the size of the nanoflakes decreases, while the density of nanoflakes on the substrate increases. The direct optical bandgap of SnS₂ photoanodes increased from 2.08 to 2.42 eV with increasing sulfurization duration. PEC measurements revealed an increase in the PEC activity with increasing sulfurization time. The SnS₂ photoanode synthesized for 60 min exhibits a maximal current density of 5.1 mA/cm² and a stable photocurrent under 630 s of light illumination. This study illustrates a simple and inexpensive method for the fabrication of an efficient and stable SnS₂ nanoflake photoanodes.