Formation of TiO2 nanostructures modified Eumelanin films with enhanced properties for biopolymer implementations

Thin films of hybrid melanin-TiO2 nanoparticles (eumelanin: TiO2) deposited from solution by electro-spray were accurately inspected to unveil modified structural and electronic properties for device implementations. Based on the reorganization of the melanin electronic valence orbital, among other interesting behaviors, we observed up to a two orders increase in the absorption coefficient in the visible range. Furthermore the red-shifted absorption features, disclose that the extended π- stacking of oligomers is mainly responsible for the tunability of the optical gap as confirmed by photoluminescence. TiO2 nanostructures via oxidative polymerization, further improve the oligomeric character observed by means of Raman scattering. Finally, the photocatalytic activity of TiO2 nanoparticles helps the saturation of shallow trap states in melanin structure and consequently enhances the charge carrier transport.