Hybrid Amino Acid‐TiO 2 Materials with Tuneable Crystalline Structure and Morphology for Photocatalytic Applications

Gamze Sarigul, Ignacio Chamorro‐Mena, Noemi Linares, Javier García‐Martínez, Elena Serrano
2021 Advanced Sustainable Systems  
TiO 2 (A), presents remarkable properties under UV light, which are very useful in photo-oxidation reactions. Some of these are, its chemical stability, low cost, availability, and low toxicity. [2] However, as it is widely known, it presents limited photoactivity under visible light. [5] [6] Furthermore, the integration of our hybrid titania containing the Ru(II) N3 dye into a photoelectrode of a low-temperature dye-sensitized solar cells (lt-DSSC) yielded the highest efficiency reported to
more » ... e for titania-based lt-DSSCs (8.75%). [7] Very recently, we have reported the first biphasic rutilebrookite organotitania nanoparticles synthesized under mild conditions using 1,10-phenanthroline as both crystal modifier and as a source of intermediate N2p levels. Owing to these features, the hybrid organotitanias exhibit outstanding photocatalytic activity under visible light irradiation. [6] In light of these results, we decided to extend our approach to other morphologies and synthetic conditions, by incorporating other organic compounds. In this contribution, we report the synthesis, characterization, and catalytic testing of a series of hybrid amino acid-titania anatase nanoparticles and rutile nanorods with enhanced photo catalytic activity under visible light irradiation. Amino acids can be effectively incorporated in titania by coordinating their amine and carboxylic groups to the titanium atom of the titania precursor. [8, 9] In fact, different amino acids have been used as shape-modifiers in the synthesis of brookite and rutile titanias, prepared with titanium metal powder and ammonia solutions. [8] The photodeposition of Pt co-catalyst on the surface of the as-synthesized brookite particles led A method to produce hybrid organotitanias, both as thin films and suspensions, showing excellent photocatalyic activity in the degradation of organic dyes in aqueous solutions under visible light irradiation is disclosed. This method is based on the in situ incorporation of an amino acid, l-tyrosine, during the synthesis of the titanias owing to its coordination and co-condensation with the titania precursor under acidic conditions. This methodology allows the fine -tuning of their crystalline structure, size, and shape by simply varying the pH of the synthesis gel, leading to anatase nanoparticles of ≈5 nm and surface areas of ≈200 m 2 g −1 at pH = 2.2, while highly crystalline rutile nanorods are formed at pH = 0. The incorporation of l-tyrosine to both anatase nanoparticles and rutile nanorods enables these materials to absorb light in the visible range due to both the decrease in their band gap, as compared to the reference materials, and the presence of additional absorption edges at wavelengths higher than 400 nm. Consequently, the photocatalytic activity of both hybrid anatase nanoparticles and rutile nanorods exhibits a 120% enhanced photocatalytic efficiency, as compared to that of l-Tyr-free titanias and the commercial P25, which confirms their potential application in water remediation.
doi:10.1002/adsu.202100076 fatcat:5nizh3falnenrh44aonhmamooe