Photoanodic properties of sol-gel-derived iron oxide thin films with embedded gold nanoparticles: effects of polyvinylpyrrolidone in coating solutions

Fe₂O₃ thin films containing dispersed Au nanoparticles were prepared on nesa silica glass substrates, using Fe(NO)₃·9H₂O-HAuCl₄·4H₂O-CH₃COCH₂COCH₃-CH₃OC₂H₄OH solutions containing polyvinylpyrrolidone (PVP). The photoanodic properties were studied in a three-electrode cell with the film sample as the working electrode and an aqueous buffer solution of pH=7 as the supporting electrolyte. The Au particles increased photoanodic quantum efficiency at wavelengths <500-600 nm. Quantum efficiency was further increased by modifying the microstructure of the film electrodes through the addition of PVP. The maximum incident photon to current efficiency (IPCE) of about 20% was achieved in an Au-dispersed film prepared from a solution containing PVP. PVP in coating solutions provided the fired films with an increase in size of the grains and voids between them and in donor density, either of which could contribute to the increased IPCE.