Bio-friendly titania-grafted chitosan film with biomimetic surface structure for photocatalytic application

A series of biomimetic chitosan (CS) films grafted with titanium dioxide (TiO₂) were successfully prepared for photocatalytic reduction of carbon dioxide (CO₂). The replication of the hierarchical structure of natural leaves to the surface of CS was conducted by nanocasting technique. The presence of amine and hydroxyl groups on CS matrix was able to anchor TiO₂ nanoparticles. The addition of cross-linking agent, glutaraldehyde, improved the denseness of CS matrix but affected the distribution of TiO₂. The existence of biomimetic structures on films enhanced the hydrophobicity, thermal stability and CO₂ adsorption. Moreover, the surface patterns influenced the optical absorption edge of TiO₂-grafted films. Under the illumination of UVA (8-Watt) light source, the TiO₂-grafted CS films were able to convert CO₂ into carbon monoxide and trace amounts of methanol. The biofriendly CS-supported photocatalysts exhibited the potential for sustainable CO₂ reduction for cleaner production of chemical fuels.