The electrochemical formation of TiO2-polyaniline (PANI) composite layers was studied by anodic polymerization of aniline in the presence of TiO2 nanoparticles. The composite layers were investigated for their electrochemical, photoelectrochemical, and surface morphological characteristics. It was found that thick composite layers showed no photoresponse, whereas thin layers, prepared by a few potentiodynamic scans, have small photocurrents almost independent of the layer thickness. Due to the small photocurrents of the composite single-layers, bi-layered structures consisting of a first pristine PANI layer followed by an outer TiO2-PANI composite layer were also studied. The bi-layered structures were found to have up to threefold larger photocurrents than the composite single layers. The TiO2-PANI composite layers were additionally modified by deposition of platinum particles using galvanostatic electroreduction or photoreduction in the presence of hexachloroplatinate anions.
