resumo
Titanium dioxide is a compound of great interest, due to its functional properties; one of its most important uses is as a photocatalyst. TiO2 coatings can be deposited using different techniques. Aerosol Assisted Chemical Vapour Deposition (AACVD) is particularly interesting, as high temperature or pressure are not necessary to generate the gaseous precursors. Furthermore, by carefully choosing the deposition conditions (i.e. deposition temperature, solvent), it is possible to obtain deposits with different morphology and, consequently, different functional properties. In this paper we present the synthesis of titanium dioxide coatings with AACVD using complexes between titanium isopropoxide (TIPP) and acetyl acetone (acac) as precursors. Deposition experiments were performed using different ratios of TIPP to acac, to assess the effect on the composition of the coatings, their morphology and photocatalytic activity. Results showed that the use of acac led to nanostructured titanium dioxide (nanoparticles of about 10 - 25 nm diameter). Raman analysis showed the presence of both anatase and ruffle phases. XPS analysis indicated the presence of residual carbonaceous species in the coatings; despite this, they displayed photocatalytic properties similar or superior to AACVD films without carbon. Photocatalytic tests, performed measuring the Formal Quantum Efficiency (FQE) and the Formal Quantum Yield (FQY) in the degradation of resazurin, showed that a acac:TIPP ratio equal to 1 led to the material with the highest performance, as the FQE value was about three times higher than that for the coating prepared with TIPP alone. Overall the complexes between TIPP and acac are promising precursors for the AACVD technique, leading to nanostructured coatings with enhanced performance.
palavras-chave
TIO2 THIN-FILM; PHOTOCATALYTIC DEGRADATION; X-RAY; ACETYLACETONATE; PRECURSOR; CARBON; PERFORMANCE; TRANSITION; NITROGEN; LAYERS
categoria
Chemistry
autores
Taylor, M; Pullar, RC; Parkin, IP; Piccirillo, C
nossos autores
Rob Pullar
Colaboradoragradecimentos
Clara Piccirillo would like to thank Fondazione con il Sud, for funding the project HApECOrk (2015-0243). Robert C. Pullar thanks the FCT (Fundacao para a Ciencia e Tecnologia, Portugal) for supporting this work through grant IF/00681/2015. This work was developed within the scope of the project CICECO -Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 FCT Ref. UIDP/50011/2020, financed by national funds and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement through the FCT/MCTES. Authors would like to thank Dr. David Tobaldi for the help with the interpretation of UV spectroscopy data and Dr. Sonia Carallo for the AFM measurements.