Tungsten trioxide film photoanodes prepared by aerosol pyrolysis for photoelectrochemical applications

The present work describes the preparation of tungsten trioxide photoanodes by aerosol pyrolysis on FTO/glass substrates. WO3 layers were characterised by profilometry, XRD, SEM and photoelectrochemistry (linear vol-tammetry and chronoamperometry under illumination). Optimal deposition conditions to obtain a relatively thick layer were found to be: 11 mm nozzle diameter, 2.5 cm nozzle to substrate distance, and 105 cm/s airflow velocity. A deposition temperature of at least 450 degrees C was necessary to obtain gamma-monoclinic WO3. The as-deposited layers had loose particles on the surface; however, these particles could be removed by scotch tape with no influence on the roughness and photoactivity of the layer. The highest photocurrent was achieved by annealing the layers at 450 degrees C; however, such layers were not photoelectrochemically stable. To obtain superior long-term stability, an annealing temperature of 550 degrees C was necessary. The highest, stable photocurrent of -990 mu A/cm2 (E = 0.9 V vs. Ag/AgCl, 1 sun) was achieved for a layer thickness of 3.8 mu m.