Photo-electrochemical properties of nanostructured WO3 prepared with different organic dispersing agents

Different chemical routes for obtaining nanostructured WO3 on transparent conductive oxides have been tried by considering the Santato-Augustynski recipe as a main guideline. The preparation started from tungstate salts as precursors and involved different organic dispersing agents. Calcination in air at 550 °C produced the final oxide. Aim of this work is to test the oxide materials as photoanodes for the photo-electrochemical water splitting. WO3 is a wide bandgap semiconductor, able to transport photogenerated carriers under irradiation, provided that it has a good crystalline structure. The morphology and the crystal size of the obtained WO3 nanoparticles have been investigated by SEM and XRD. This work shows that the particle size of the WO3 film decreases with increase in molecular weight of the organic dispersing agents. The current–voltage characteristic curves of WO3-based electrodes have been obtained by biasing a photo-electrochemical cell with an external voltage ramp, both in the dark and under simulated solar irradiation. Results showed that under incident irradiance a noticeable photocurrent density is obtained with a reasonably steep current–voltage slope and with a plateau current of the order of 1.6–1.8 mA/cm2 under incident 0.14 W/cm2 AM 1.5 irradiation.