Facile Approach of Direct Sulfidation of FTO to Form Vertically Aligned SnS₂ Nanoflake Photoanodes for Efficient Photoelectrochemical Water Splitting

Two-dimensional (2D) metal dichalcogenides, such as SnS2, have emerged as a potential material for photoelectrochemical applications due to their suitable band alignment for water splitting, high charge carrier mobility, and significant optical absorption in the blue-green spectral range. In the present work, vertically aligned SnS2 nanoflakes (NFs) were grown on quartz glass/fluorine-doped tin oxide (FTO) using a sulfidation method in a H2S furnace at 450 °C for various times. The effects of FTO thickness and H2S treatment time are systematically investigated on the crystal structure and optical and photoelectrochemical characteristics. The highest incident photon to current conversion efficiency (IPCE) achieved (up to 60%) is for 2-μm-thick FTO NFs, which balances the competing requirements of a high photogenerated charge carrier, transport, and light absorption. The optimized vertical SnS2 NF photoanodes generate a photocurrent of 2.3 mA cm–2 at an applied bias of 0.2 V (vs Ag/AgClSat) for water splitting without any hole scavenger. Such a simple approach of direct growth of vertically aligned SnS2 NFs on FTO offers a viable scheme for the fabrication of high-performance photoelectrochemical photoanodes.