Hematite-Based Photoelectrochemical Water Splitting: Hydrothermal and Layer-By-Layer Synthesis Methods

In this study, four different photoanodes were prepared by hydrothermal and layer-by-layer (LBL) methods and compared for their photoelectrochemical (PEC) water splitting capabilities. All four samples were grown on F-doped tin oxide (FTO) glasses. Both TiO2 and Fe2O3 were coated by a LBL method on FTO glasses and heat-treated at 500 degrees C to obtain TiO2/FTO and Fe2O3/FTO. Hematite (alpha-Fe2O3) thin films and Ti-doped hematite were hydrothermally deposited on the surface of the FTO glasses and heat treated in air at 550 degrees C and at 750 degrees C to generate alpha-Fe2O3/FTO and T-Fe2O3/FTO. The photocurrent density of Ti-Fe2O3/FTO in water splitting reactions reached 2.04 mA/cm(2) at 1.23 V (vs. the reversible hydrogen electrode) owing to decreased band gap energy, electron hole recombination, and fast electron transfer processes enabled by the short distance between the active materials and the conducting electrode. This value was almost 1.1 times higher than that achieved by undoped hematite heat-treated at the same temperature, thereby illustrating the best photocatalytic activity among all samples. Our result may introduce a way for energy conversion applications and high-efficiency hematite-based PEC systems.