Photocatalytic and Antibacterial Properties of Doped TiO2 Nanopowders Synthesized by Sol−Gel Method

Abstract

For environmental applications, nanosized TiO2-based materials are known as the most important photocatalyst and are intensively studied for their advantages such as their higher activity, lower price, and chemical and photoresist properties. Zn or Cu doped TiO2 nanoparticles with anatase crystalline structure were synthesized by sol−gel process. Titanium (IV) butoxide was used as a TiO2 precursor, with parental alcohol as a solvent, and a hydrolysing agent (ammonia-containing water) was added to obtain a solution with pH 10. The gels were characterized by TG/DTA analysis, SEM, and XPS. Based on TG/DTA results, the temperature of 500 °C was chosen for processing the powders in air. The structure of the samples thermally treated at 500 °C was analysed by XRD and the patterns show crystallization in a single phase of TiO2 (anatase). The surface of the samples and the oxidation states was investigated by XPS, confirming the presence of Ti, O, Zn and Cu. The antibacterial activity of the nanoparticle powder samples was verified using the gram−positive bacterium Staphylococcus aureus. The photocatalytic efficiency of the doped TiO2 nanopowders for degradation of methyl orange (MO) is here examined in order to evaluate the potential applications of these materials for environmental remediation.

Copper-/Zinc-Doped TiO2 Nanopowders Synthesized by Microwave-Assisted Sol–Gel Method

“…The Cu 2p spectra show some additional peaks, which are satellites (peaks arising from various less-likely electron transitions). It can be observed that, in this case, there are some changes in the shape of the spectra, and the most significant one relates to the satellite peaks at ~945 eV and 967 eV, confirming the presence of the Cu(II) valence of Cu [ 67 ]; this can be assumed to result from the preparation method, as the presence of this valence was not observed when the samples were synthesized only by the sol–gel process [ 35 ].…”

“…Except for the microwave irradiation, the preparation method and the reagents were previously described in Ref. [ 35 ]. The solution was exposed to microwave irradiation for 10 min at 200 W in an oven operating at a frequency of 2.45 GHz with a maximum power of 2000 W. To remove the water and organic residues and obtain crystallized nanometer-sized powders, the resulting oxide powder was filtered out of the solution, washed with distilled water to remove adsorbed compounds, dried, and then thermally treated at 500 °C in the air with a plateau of 1 h and a heating rate of 1 °C/min.…”

“…Increasing TiO 2 activity efficiency under the visible light range is one of the most desired improvements, and a facile way to accomplish that is by TiO 2 modification with metal or nonmetal elements. Thus, intermediate energy levels are created by the dopants which reduce the band gap of TiO 2 [ 35 ]. Furthermore, a better separation of electron–hole pairs is obtained by providing new sites that capture photogenerated electrons, leading to an increase in photocatalytic efficiency [ 36 ].…”

Sol–Gel-Derived TiO2 and TiO2/Cu Nanoparticles: Synthesis, Characterization, and Antibacterial Efficacy

“…In most cases, high calcination temperatures and high concentrations of Cu were used to make Cu-doped TiO 2 for antibacterial activities. Furthermore, the synthesized materials proved to be effective under dark conditions, wherein, similar materials reported no activity as shown in Table , while others used light source such as UV light for antibacterial activity …”

Gels: Synthesis, Characterization and Applications in High Performance Chemistry

“…The antibacterial activity of the nanoparticle powder samples was verified using the Gram-positive bacterium Staphylococcus aureus. The photocatalytic efficiency of the doped TiO 2 nanopowders for the degradation of methyl orange (MO) was examined here to evaluate the potential applications of these materials for environmental remediation [ 7 ].…”