Effects of Cu, Zn and Cu-Zn addition on the microstructure and antibacterial and photocatalytic functional properties of Cu-Zn modified TiO2 nano-heterostructures

abstract

Titanium dioxide (TiO2) is well established as one of the most common photocatalysts used for many environmental, anti-pollution and antibacterial applications. However, in this work, novel photocatalytic TiO2 nanopowders were modified with additions of 1 mol% copper, zinc or copper+ zinc (with various Cu: Zn ratios). These were prepared via a green sol-gel route and thermally treated at 450 degrees C. For the first time, a direct comparison of the effects of these two modifying agents was performed, both as single and co-substitution. The compounds were thoroughly characterised by means of advanced X-ray diffraction (Whole Powder Pattern Modelling, WPPM) and spectroscopic methods (Raman and UV-vis). For functional properties, the photocatalytic activity in the gas-solid phase (nitrous oxides (NOx) and isopropanol degradation (VOCs)) was tested under UV and visible light, and antibacterial activity against Gram positive and Gram negative bacterial strains was also investigated. Neither copper nor zinc entered into the TiO2 structure, but nucleated as oxides at the surface of titania nanoparticles, thus creating a nano-heterojunction between the semiconductor materials; this also retarded the anatase-to-rutile phase transition. When comparing and contrasting their functional properties, it was found that Zn modification gave greater photocatalytic activity than that with Cu. On the contrary, for antibacterial activity, copper was shown to be a better additive. Co-modification with both metals did not improve the antibacterial behaviour, but did lead to an increase in photocatalytic activity in some cases. (C) 2016 Elsevier B.V. All rights reserved.

keywords

SOL-GEL SYNTHESIS; TITANIUM-DIOXIDE; DOPED TIO2; OPTICAL-PROPERTIES; ANATASE TIO2; RUTILE; NANOPARTICLES; OXIDATION; BROOKITE; NANOPOWDERS

subject category

Chemistry

authors

Tobaldi, DM; Piccirillo, C; Rozman, N; Pullar, RC; Seabra, MP; Skapin, AS; Castro, PML; Labrincha, JA

Groups

G4 - Renewable Materials and Circular Economy

Projects

ECO-SEE – ECO-innovative, Safe and Energy Efficient wall panels and materials for a healthier indoor environment (ECO-SEE)

CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)

acknowledgements

D.M. Tobaldi is grateful to the ECO-SEE project (funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 609234). R.C. Pullar and C. Piccirillo acknowledge the support of FCT grants SFRH/BPD/97115/2013 and SFRH/BPD/86843/2012, respectively. N. Rozman and A. Sever Skapin thank Slovenian research agency (ARRS) for the financial support. This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement.