Effect of silicon doping in nanostructured hematite thin films for photoelectrochemical hydrogen generation

In this work, the researcher concentrated on the synthesis and analysis of the properties of Si-doped nanostructured hematite ([Formula: see text]-Fe 2 O[Formula: see text] thin films, aiming to use them as photoelectrodes in photoelectrochemical (PEC) cells for the production of hydrogen. Spray pyrolysis, deposition method is used for thin-film synthesis to achieve uniform, nanostructured layers with controllable doping levels. The confirmation of the hematite phase by XRD ensures that the desired [Formula: see text]-Fe 2 O 3 structure was achieved in both doped and undoped films. Scanning Electron Microscopy (SEM) analysis, revealing surface morphology and nanoscale structures, provided insights into how Si-doping affected factors like grain size, porosity, etc. The significant visible light absorption observed ([Formula: see text]2.1[Formula: see text]eV) aligns well with the band gap of hematite, which is promising for PEC applications. Furthermore, the marked improvement in photocurrent — specifically, a threefold increase ([Formula: see text]680[Formula: see text] [Formula: see text]A/cm 2 at 0.7[Formula: see text]V/SCE) at a 0.002 M Si-doping concentration highlights the effectiveness of Si doping by introducing favorable electronic changes, potentially increasing the conductivity of the hematite. The substitution of Fe[Formula: see text] ions by Si[Formula: see text] in the [Formula: see text]-Fe 2 O 3 lattice likely contributes to enhanced charge separation and reduced recombination rates that are the critical factors in sustaining higher photocurrents.